Office of Operations Freight Management and Operations

MODULE 5: Trip Operations

This module contains many of the "nuts and bolts" of escort vehicle operations, including the role of the P/EVO, positioning of the front (or lead) escort and the rear escort (also called the chase car), safe operation of the escort vehicle, how and when to deploy equipment, controlling traffic, railroad crossing hazards, and emergency operations.

This module includes six lessons: The Role of the P/EVO, Equipment Use, Roadway Positioning and Procedures, Traffic Control, Railroad Crossings, and Emergency Procedures.

Oversize load movement "may require multi-jurisdictional permits. These permits may have differing restrictions, conditions, and regulations, which may result in cumbersome and confusing procedures. This process is further complicated by the lack of State standards for P/EVOs. The resulting delays, inconsistencies, and unpredictable procedures have long created havoc for the transportation industry," according to the 2004 edition of the P/EVO Best Practices Guidelines.71

Now, more than a decade later, these conditions persist. Permits are still issued by States that have differing requirements for equipment, curfews, P/EVO certification and training requirements, and other differences. Very few regional permits are available, and no national standards for P/EVOs exist. Inconsistencies in requirements and procedures continue to produce delays and less-than-optimal safety conditions in the movement of oversize loads, in addition to presenting a maze of rules and requirements that is difficult to negotiate and provides little if any benefit.

It must be clear to individuals operating pilot/escort vehicles that P/EVOs must stop at all stop signs and traffic lights, must yield to oncoming traffic, and must follow all laws and regulations in the jurisdictions in which they operate. It is never appropriate for P/EVOs to ignore stop signs and traffic signals, speed limits, move- over laws, to cross centerlines, run motorists off the road, or to violate any other traffic laws.

Characteristics of Oversize Loads

P/EVOs must remember that the oversize load is operationally more difficult to drive and has more blind spots. The oversize load is less maneuverable, takes longer to stop and accelerate, and has a wider turning radius. Drivers of oversize load vehicles have difficulty maintaining speeds on roads with moderate to severe grades. The oversize load vehicle is less stable, some are more likely to roll over, and they are often subject to trailer sway and rearward amplification,72 tail swing, offtracking, and other phenomena.73

P/EVOs must be prepared to deal effectively and safely with oversize loads, including accommodating these characteristics:

  • Oversize loads require extended distance to stop, change lanes, and pass other vehicles. P/EVOs assist by warning motorists when the load is going to change lanes, pass another vehicle, etc.
  • Oversize loads have more blind spots, and the blind spots are larger than in other vehicles. It is important for the P/EVO to warn load drivers of hazards they cannot see. P/EVOs must warn load drivers in time for the driver to react and to also warn motorists to keep them from striking the load.
  • Oversize loads also have difficulty gaining sufficient speed on acceleration ramps to merge with traffic on multi-lane highways, and may have difficulty braking on long and steep downgrades.
  • When making turns, the oversize load may swing wide before turning. In addition, an extremely long load may block at least two lanes of the roadway it is turning from as well as simultaneously blocking at least two lanes of the roadway it is turning onto. P/EVOs should know how to control traffic anytime the load is blocking a lane of traffic, especially when the load must move into oncoming traffic. When authorized, P/EVOs must continue to control traffic until the travel lane is clear. See also Lesson 4, below.
  • When starting movement on an inclined surface, the oversize load may roll backward. Rear P/EVOs must be aware of this and prohibit vehicles from getting too near the rear of a load when on an incline.
  • Avoid situations that make it necessary for the load driver to back up. Spotters are needed, as described in the next section.

Parking and Backing Issues

While parking the load vehicle is clearly the load driver's domain, the P/EVO may help the driver avoid all situations in which the load vehicle must back up. If the P/EVO is familiar with the route, this can be very helpful to a load driver who is not familiar; for example, the P/EVO may know about safe places to park the oversize load, or to sleep, get fuel, or food. Backing a truck is always dangerous; oversize loads, especially articulated loads, carry enhanced risks. When parking, the P/EVO should assist the driver in finding a location that allows the load vehicle to be moved forward when resuming travel.

If a longer combination vehicle or any load vehicle must be moved in reverse, the P/EVO must be prepared to assist the load driver. Having the P/EVO serve as a spotter is important. The P/EVO should check all around the vehicle (preferably with the load driver). Monitor clearances front and rear, above and below, and on both sides of the load vehicle as it moves. Spotters should always stand on the driver's side of the vehicle once the backing begins, and move with the load in order to remain visible to the driver at all times. The spotter must be able to see the driver at all times. Spotters and drivers must agree upon a set of hand signals, especially a clear signal for "stop."74

Stopping Distances

Safe driving practices can very frequently be linked to stopping distance. Therefore, it is crucial that P/EVOs understand the risks they are taking when they fail to operate in ways that allow for the limitations of the load and the presence of other motorists.

Stopping distances increase by the SQUARE of the amount the speed is increased.

So if speed doubles from 20 mph to 40 mph, the distance needed to stop increases by 4 times.

Trucks often weigh 20 to 30 times as much as passenger vehicles, and trucks are taller, often with greater ground clearance, resulting in smaller vehicles under- riding trucks in crashes. This is a special concern for rear pilot/escort vehicle operators (P/EVO).75

Compared with passenger vehicles, stopping distances for trucks are much longer, and trains are much longer than trucks. Loaded tractor-trailers take 20 to 40 percent more distance than cars to stop, and the discrepancy is greater on wet and slippery roads or with poorly maintained brakes.76 This is important for the lead P/EVO, in particular. For more information about stopping distances, see Module 7, Lesson 4.


  1. When is it appropriate for P/EVOs to ignore traffic laws?
  2. What are common characteristics of oversize loads that P/EVOs must understand and accommodate?
  3. How is stopping distance affected by speed?


As discussed in previous modules, the roles assigned to P/EVOs differ substantially from State to State, as do training and certification requirements, insurance requirements and other aspects of operating a pilot/escort vehicle. It is generally agreed among the States that the P/EVO is responsible for warning motorists about the presence of an oversize load. In addition, where permitted by State law, the P/EVO is also responsible for controlling traffic, often in conjunction with law enforcement escorts, to allow the oversize load driver to negotiate turns, avoid striking roadway structures and vehicles, and adapt to traffic conditions.

Even though many States do converge to some degree on these purposes, variations within these categories also exist. For example with respect to warning motorists, the major consistency is that all States require an Oversize Load sign on all vehicles (load and escort vehicles); however, the size of the sign varies, as do rules about where on the escort vehicle the sign must be displayed. The color scheme is consistent for the signs across States (black letters on yellow background), yet the size of loads that require the signs varies. This situation is perhaps one of the most difficult tasks the P/EVO encounters: How to comply with diverse and differing rules and permit restrictions in each State and local jurisdictions.

Standardizing P/EVO rules, processes and procedures is an important safety issue. Uniform operating procedures, designed with safety as the primary goal, reduce confusion of highway users, load movement team, and even enforcement officers, as well as promoting effective operations and improving load movement safety.


Each State has rules about the allowable size for loads moving on highways within the State. When loads exceed these allowable limits, the State issues a permit that specifies when the load can be moved, the route the load must follow, the number of P/EVOs required, and other information. The commercial carrier must have the necessary permits, and it is important for P/EVOs to review all permits carefully. Routes are selected first and foremost to provide extra measures of safety for the general public. With safety as the primary focus, the route may involve increased distances, or restrictions on specific times of movement that make the load movement more time consuming or difficult. However, failure to follow the route as specified on a permit constitutes a violation of the permit that in most States renders the permit invalid.77

Even though the carrier is the permit holder, it is important that the escort also comply with permit requirements. Violations that occur include failing to comply with provisions in the permit in terms of route or curfew, for example, or providing false information in order to get a permit.

Load Movement Preparation

As discussed in Module 4, transporting oversize loads requires extensive planning. Moving large loads will often involve not only P/EVOs but also law enforcement escorts and utility crews to move electric or other lines or to facilitate traffic control. With State-issued permits and the variance in rules among the States, planning is critical to ensure the load movement is being performed safely and in compliance with the many applicable State and local rules.

Just prior to load movements, P/EVOs should check communication equipment, make sure lights are on, and all paperwork is in the vehicle. And, in the last few minutes before the load moves, P/EVOs should do the following:

Paperwork check: Licenses, P/EVO cards, Transportation Worker Identification Credential (TWIC) cards,78 insurance, copies of permit, route survey, and maps.

Vehicle check: All required equipment for all States, warning light and headlights on, signs displayed, flags in place, height pole installed and calibrated, if required.

Route check: Ensure all load movement team members know the route, and specifically review the first few turns and/or the route and all known hazards up to the next stop. Discuss curfews and parking issues, identify the next planned stop and any emergency pullover areas along the route.

Traffic Control Plan(s): Review flagging procedures for narrow bridges or turning long loads. Ensure all team members know what to do and when to stop traffic if required and allowed.

Communication equipment check: Select channel and test all equipment, identify team members, and establish voice recognition.

Emergency procedures: Review with the entire team the immediately relevant emergency procedures, such as becoming lodged at a crossing or experiencing a vehicle breakdown.

Before movement, each member of the load movement team should adjust mirrors and seat, set radio channel and volume, heat/air controls, and put on safety vest.

Inspection and Monitoring During Load Movement

During the trip, P/EVOs should report everything they see, hear, smell, or anything that feels or looks different in the way the vehicles or load rides or handles.79

The load and escort vehicles should be inspected at every stop, as well as monitoring all dashboard instruments including temperature and oil pressure gauges, tire pressure and warning lights while on the road.

Immediately after starting the day, rear P/EVOs, especially, should pay attention to the load and securement devices. P/EVOs must notify load drivers immediately if the cargo shifts or any securement device slips or loosens, or any other situation arises with the load vehicle or cargo that may create an unsafe environment for motorists, including the P/EVO following the load.

Pilot/Escort Vehicle Operators Responsibilities

It is vital that P/EVOs communicate with motorists near the oversize load by signaling intentions to turn or change lanes as far in advance as possible. When making lane changes, turn signal on earlier than under normal circumstances. The escort should change lanes first, in order to protect the load from oncoming traffic, and vice versa, during the lane change. The entire load movement team should change lanes slowly and smoothly so that other motorists have time to honk or move out of the way in the event the P/EVO doesn't see a vehicle moving in a blind spot or blocked by vehicle pillars. It is important to remember that a motorcycle can be blocked from view by an object no bigger than a pencil.80

Similarly, it is crucial to warn drivers approaching from the rear of the oversize load when slowing down. Tap the brake pedal a few times to flash brake lights to warn drivers when slowing down. This is especially important in hilly terrain, on curvy roadways, and on wet surfaces.

P/EVOs and load drivers must slow down gradually and signal their intentions early. They must do everything possible to avoid forcing the load driver to stop suddenly. Motorists do not realize how fast, at highway speeds, they close the gap between their vehicle and a slow moving vehicle. It is important to use every lawful means to warn approaching motorists of slow moving loads.

Likewise, oversize loads make it particularly difficult for motorists behind the load to see hazards ahead. The rear P/EVO and the load driver must do everything they can to alert drivers to hazards and when it is unsafe to pass, for example.

It is NOT recommended that P/EVOs or load drivers wave cars around or make any attempt to signal other motorists when it may be safe to pass. The load driver and the P/EVOs must focus on the specific job they are doing. It is not possible to drive safely and to direct traffic simultaneously.

When delaying traffic more than 5 minutes or when more than five vehicles are behind the load, if possible, move over and allow the vehicles to pass. In certain situations, it may be necessary for the load and P/EVOs to stop and flag traffic around the load (See Lesson 4, below).

Role of the Lead Pilot/Escort Vehicle Operator

Lead car responsibilities include navigation, communication, height pole operation, and providing adequate warning to motorists. It is the lead P/EVO who must also monitor and evaluate hazards in real time and communicate about hazards in enough time for the load driver to successfully negotiate the hazard.

The lead P/EVO should maintain a position that gives a range of vision that exceeds that of the load driver, and be alert for changes in the surroundings.

Maintaining an attentive and proactive visual lead is perhaps the most important skill front P/EVOs must cultivate. Monitoring obstructions such as signs, guardrails, and mailboxes is critical to the safe movement of oversize loads, but monitoring is only the beginning of this task. If the distance between the escort and the load is too small, or if the P/EVO does not notice the hazard in time to notify the driver, no amount of monitoring will ensure the safety of highway users, the load driver, the P/EVOs, and transportation infrastructure. Even if the P/EVO has time to notify the load driver about the hazard, there is frequently no time left for the driver to avoid it. This also highlights the vital nature of effective communication equipment and processes.

The visual lead every member of the team should maintain varies with the speed of the traffic, weather conditions, features of the terrain, and other factors. Similar to recommended following distances, an adequate visual lead is at least 20 seconds for oversize load movement, and more lead time should be added for each hazard that exists in a given situation, such as a wet roadway, darkness, hills and curves, driver fatigue, or traffic congestion.

Seeing Hazards

First, what is a hazard? Any road condition or other road user (driver, bicyclist, pedestrian) that is a possible danger.81 For example, a car in front of you braking suddenly, or heavy rain in a dark work zone. Seeing hazards increases preparedness. If prepared and vigilant, drivers can frequently avoid hazards that can become emergencies. Monitoring mirrors and scanning at least 20 seconds ahead, as well as managing space around the oversize load vehicle, reduce risk and increase the time available to react to hazards.82 To be safe, all drivers must know what is going on all around the vehicle. Inattention is a major cause of crashes. When escorting oversize loads, the P/EVO must look much farther ahead than when operating a vehicle under ordinary conditions.

Lean forward and elevate the body if needed to see around mirrors, A-pillars and other obstacles, especially when merging or changing lanes.

The P/EVO has reduced effectiveness if the scope of vision is limited to what the load driver can already see. The lead P/EVO should maintain a position that gives a range of vision that exceeds that of the load driver, and be alert for changes in the surroundings.83

The load vehicle takes longer to stop and maneuver, and depending on its size and weight, load vehicles are not capable of making quick adjustments in speed and direction, as mentioned. For oversize loads, stopping and changing lanes, for example, take a lot more distance. Changing lanes and entering and exiting roadways must be planned well in advance. Adequate distance between the load and P/EVOs and between the load and all other vehicles on the roadway must be maintained in order to operate safely when unexpected events occur, such as experiencing mechanical problems, encountering stalled or abandoned vehicles or other obstructions, or weather conditions.

In day-to-day driving, vigilant drivers look at least 12 to 15 seconds ahead, while continually monitoring mirrors, nearby vehicles, and traffic control devices. At lower speeds, that is about one block. At highway speeds in good conditions, recommended following distance is 3 seconds. For P/EVOs and the oversize load driver, those distances should be doubled. P/EVOs and load drivers should be monitoring at least 30 seconds ahead and following distances should be increased to 6 seconds in good conditions; that is, flat, level, dry, pavement in daylight.

Attentive drivers (i.e., non-distracted, well rested) direct their attention to mirrors, seeing ahead, and seeing near to far, as well as monitoring instruments and warning indicators, the load and load vehicle, and nearby vehicles.

Road Work Ahead sign.
Figure 1. Photo. Manual on Uniform Traffic Control Devices (MUTCD) work zone warning road sign.
Source: FHWA

Warning sign reads: State Law, No Texting, No Hand Held Cell Phone.
Figure 2. Photo. Maryland road sign.
Source: Maryland DOT

However, for the lead P/EVO, even these attentive behaviors are not adequate. Because of the size and weight of loads and load vehicles, maneuverability is much more difficult and represents a highly dangerous situation for even basic operations such as changing lanes or stopping for a roadway obstruction. Lead P/EVOs in particular must look for vehicles coming onto the roadway, changing lanes, or turning, as well as watching for brake lights from slowing vehicles. It is important to adjust to traffic lights sooner when escorting oversize loads. For example, if a traffic light has been green for a long time, the load will need to slow down and prepare to stop in situations in which a passenger car would likely be able to make it through the intersection.84

Other Hazards

Hazards to be aware of, especially for lead P/EVOs and load drivers, include those related to roadways and infrastructure and hazards related to other drivers.85 Roadway hazards include work zones, edge drop off, foreign objects, on/off ramps, overhead obstructions, changes in elevation, and other hazards.

Work Zones. Speeding traffic is the number one cause of injuries and death in work zones, and speeding is the number one citation issued to drivers in work zones. To operate safely, P/EVO and load drivers must observe posted speed limits at all times, and especially when approaching and driving through work zones. Drivers must be mindful of their speed and avoid increasing speed while traveling through the work zone, especially long sections of construction.

Maintain adequate following distance, and decrease speed in adverse weather or road conditions, and when workers are near the roadway. Work zones often involve narrower lanes, sharper turns, and uneven surfaces in addition to the more significant hazards that exist when workers are near highway traffic. Other drivers may be distracted or confused in an active work zone, and construction workers themselves are often focused on their jobs, so it is crucial that P/EVOs, oversize load drivers, and all drivers adopt a policy in order to remain alert and prepared for changes in driving conditions and all drivers refrain from using any devices in work zones, in order to remain alert and prepared for changes in driving conditions.

Edge Drop-off is dangerous because driving too near the edge can tilt vehicles toward the side of the road, causing the top of the vehicle to hit roadside objects (signs or tree limbs, for example), especially when over-steering occurs. Driving off the edge is dangerous and negatively affects steering. Top-heavy vehicles may roll over. Attempting to come back onto the road too quickly or at speeds that are too fast can produce a crash. If a vehicle drives off the edge of the road surface, let off the accelerator and gradually steer back onto the road once speed is adequately reduced. For load vehicles, this is particularly dangerous, and severe damage can be inflicted when load vehicles hit potholes, ruts, or other irregularities in the surface of the roadside or the edge of the pavement.

Foreign Objects that have fallen onto the roadway are also potential hazards. Such objects can be a danger to tires and wheels on any vehicle, or may damage the load vehicle's electrical or brake lines. Objects can also get caught between dual tires and cause severe damage. Some obstacles may appear to be harmless but are actually very dangerous. Cardboard boxes may be empty, or they may contain some solid or heavy object capable of causing damage or producing a loss of control. Bags, even empty ones, can become wrapped around vehicle parts and create breakdowns and damage. Monitoring space ahead far enough in front of the vehicle to avoid obstacles is critical. The lead P/EVO must be especially vigilant, and maintain adequate distance from the load to allow the load driver enough time to respond to road hazard information provided by the P/EVO.

On/Off Ramps can be particularly dangerous for large vehicles. Posted speeds on ramps are safe for well-maintained passenger vehicles operating in good conditions, but may not be safe for large, heavily loaded vehicles. Exits that slope downhill and turn at the same time can be especially dangerous. The downgrade makes it difficult to reduce speed. Braking and turning at the same time can be a dangerous practice. It is important to drive slowly enough before getting to the curved part of an on/off ramp.86


  1. What are the primary duties of P/EVOs?
  2. What are the benefits of standardizing P/EVO rules, requirements, processes and procedures?
  3. What determines the route for oversize loads?
  4. What must the load movement team do just prior to load movement?
  5. What must all P/EVOs do during load movement?
  6. When should load drivers and/or P/EVOs signal to motorists when it is safe to pass the oversize load?
  7. When should the load and P/EVOs pull over and allow traffic to pass?
  8. What is the primary skill that lead P/EVOs, in particular, must develop?
  9. What is the number one cause of injuries and death in construction work zones?

Role of Rear Pilot/Escort Vehicle Operator

When the P/EVO is behind the load, the tasks for safe load movement include watching motorists approaching from the rear, watching the amount of traffic behind the load, and reporting information to the team. Additionally, the rear escort (also known as the chase car) must watch the load vehicle itself to report shifting of load, flat tires, tie-down malfunctions, and anything about the load and load vehicle that might interfere with safe load movement.

Seeing to the Sides and Rear. P/EVOs must monitor mirrors and warn traffic nearby of the presence of the oversize load—that is the P/EVO's primary mission. And, it is important to notify the load driver of potential hazards.87 As with all drivers, the rear P/EVO must continually monitor mirrors and be aware of nearby motorists. It is important to monitor vehicles to the sides of the escort and load vehicles in case an evasive maneuver is required, such as an unexpected lane change. It is vital that the load driver and P/EVOs remain in contact to warn of hazards that arise from front, rear, and sides. Basic maneuvers are potentially dangerous situations when they involve oversize loads. This includes lane changes, turns, merges, and other tight maneuvers.

Lane changes require the rear P/EVO to notify the load driver when the lane is clear and then to move into that lane before the load does. Once the rear P/EVO is blocking the lane to other traffic, the load can move into the lane. This is the best practice, whether moving into a lane to the left or to the right. When turning, depending on the size of the load, make sure the rear of the vehicle will not hit anything (see the Off tracking section, below), particularly signs and signal devices. Many situations involving oversize loads produce tight maneuvers that under ordinary circumstances are easily accomplished. With long loads, making a turn may involve every lane at the intersection for example, which means the P/EVOs are required to warn traffic and, in many States, control traffic in order to complete a "simple" right turn.

As mentioned in previous modules, the primary job of the P/EVO is to warn traffic of the presence of the oversize load; however, the rear P/EVO must also monitor the load vehicle, the load/cargo, securement devices, tires, lights, as well as traffic coming from behind. It is especially important to notify the load driver when other large vehicles are approaching.

Load-related Hazards

Although it is not typical that the P/EVO is involved in the loading and securing of the cargo, the rear escort in particular has an inherent and keen interest in this process. If cargo is loaded incorrectly or is not secured properly, it can be a danger to any motorist operating nearby, including the rear P/EVO.88

Loose cargo that falls off a vehicle at best can cause traffic problems. At worst, they can cause crashes that injure or kill motorists. Loose cargo can also kill load drivers during a quick stop or a crash. Further, vehicles can be easily damaged when they are overloaded, and steering, tire, and/or brake performance may be negatively affected.

If hazardous materials are involved, it is important for the P/EVOs to know what the load vehicle displays and placards mean. As mentioned, the P/EVO can be of little assistance when emergencies with hazardous materials occur if the P/EVO is unaware of what the hazardous materials are and how they are to be handled in the event of a spill, for example. These issues must be adequately addressed during pre-trip planning. Having the proper fire extinguishers should be discussed, for example. Emergency procedures and contact information for reporting emergencies for each State and major local jurisdictions should be distributed to the load movement team.

Securing cargo by blocking the front, back, and sides of a piece of cargo, as appropriate, is effective for keeping the cargo from sliding. Blocking is shaped to fit snugly against cargo and be secured to the cargo deck to prevent movement of the load. Bracing is also used; bracing goes from the upper part of the cargo to the floor or walls of the cargo compartment. Cargo tie downs are used on flatbed trailers or trailers without sides. Even in closed cargo compartments, tie downs help prevent the load from shifting.

Tie downs must be of the proper type and proper strength. If possible, the P/EVO should carry extra tie downs. Tie down equipment includes ropes, straps, chains, and tensioning devices (winches, ratchets, clinching components). Tie downs must be attached to the vehicle correctly (i.e., hooks, bolts, rails, rings). It is important for the safety of the public, and especially the rear P/EVO, that the load be secure. Loads should be covered when people, especially those traveling behind or beside the load, must be protected from spilled or airborne cargo, loose chains, or other securement devices.89

The weight of the load should be balanced to prevent steering and handling issues. Too much weight can damage axles and tires. If weight is too far to the rear, steering is negatively affected and drive wheels may spin easily. It is important that all load movement team members be extra vigilant anytime equipment is being used in a way that stresses its capabilities (for example, vehicle weight limits).

After starting the trip, especially the first few miles, the rear P/EVO should inspect the cargo and the securing devices in place. As mentioned, load drivers typically check the load after the first 50 miles of driving. At this point, it is advisable to stop, if safe to do so, to perform a more detailed inspection of all the securing devices and the cargo. After that, the load should be checked every 3 hours or 150 miles of driving. Assist the load driver in checking the load carefully at every opportunity, including fuel stops, food and rest stops.90


Offtracking occurs when a vehicle's front and rear wheels do not follow the same path. An oversize load typically has a large turning radius. This limitation may result in excessive offtracking when the vehicle turns through an intersection, negotiates an interchange, or rounds a curve. The danger is that offtracking may result in lane encroachment. The P/EVO must understand this maneuvering limitation to adequately protect motorists. The extent of offtracking generally increases with the spacing between the axles of the vehicle and decreases for larger radius turns.

The extent of offtracking is defined as the distance between the path of the front inside wheel and the path of the rear inside wheel as a vehicle traverses a curve or turn. Offtracking is a function of the wheelbases of the tractor and trailers and the number of articulation points. If the width of the vehicle plus the amount of offtracking exceeds the width of the travel lane, then the vehicle will encroach into adjacent lanes, onto the shoulder, or run off the road during the turning maneuver.91

The length and number of articulation points have the greatest effect on trailer stability. The vehicle will be less stable if the trailer is shorter and there are a greater number of articulation points. Although the P/EVO typically has no involvement in determining the configuration of the load vehicle, knowledge of these vehicle stability factors contributes substantially to safe load movement.

Top-Heavy Loads

A high center of gravity increases rollover chances. For top-heavy loads, P/EVOs must be vigilant about warning drivers of curves and slopes on entry/exit ramps, for example. Oversize loads are frequently susceptible to rollover incidents.

They are subject to trailer sway, tail swing, and rearward amplification (defined as the tendency of the trailer to exaggerate the side-to-side motions of the preceding unit).92 The vehicle's level of stability is affected by the height of the vehicle's center of gravity; weight and load distribution; type and condition of connections; number of articulation points; trailer length, type, and condition; road demographics; speed; and driver skill.

Ground Clearance

Trailers today sometimes have only a few inches of ground clearance. This is a critical concern for the oversize load driver encountering a change in grade, such as a railroad crossing. P/EVOs and route surveyors must assess each railroad crossing and other grade changes along the route when escorting low-clearance loads, even sections of rough roadway surface or rocks in the roadway. Some loads are not even carried on trailers, but are suspended between trailers, leaving the load skimming barely above the surface of the roadway.

Being Prepared

Effective P/EVOs prevent incidents in spite of the unsafe actions of other team members or highway users in general. Anticipating hazards and knowing proper responses that protect the public, the team, and the load are the central responsibilities of every P/EVO. Being alert and free of visual, physical, and mental distractions is also necessary. Being alert means watching, recognizing, and communicating hazards. The ability to assess traffic situations as far ahead as possible is crucial to safe load movement. A constant assessment of the levels of risk is necessary.

The P/EVO must anticipate traffic problems likely to develop and communicate clearly the problem to the load movement team. Competent P/EVOs operate in a manner that avoids enabling the team to be involved in or contribute to a collision. Awareness of the maneuvering limitations of the oversize load, including offtracking, high center-of-gravity, low ground clearance, and articulation points, is critical to safe load movement.

Driver-Related Hazards

Driver-related hazards include blocked vision, delivery trucks, double-parked and other parked vehicles, pedestrians and bicyclists, distractions, children, workers, disabled vehicles, accidents, shopping areas, schools, confused drivers, slow drivers, drivers signaling a turn, drivers in a hurry, and impaired drivers, among other risky conditions and behaviors.

Drivers who can't see other vehicles are dangerous; for example, drivers of cargo vans and panel trucks. Be alert for such vehicles, including vans, motor homes, loaded station wagons, and cars with the rear window blocked. Watch other trucks carefully, especially rented ones! Vehicles with frosted, ice-covered, or snow- covered windows are hazards, as well.

Delivery trucks can present a hazard in part because packages may block the driver's vision. In addition, these drivers are often in a hurry and make frequent and sudden stops. Parked vehicles also present hazards, especially to oversize loads. People fail to look before getting out of parked vehicles, or drivers may pull out in front of oncoming traffic. Whenever possible, create a lane between your vehicle and parked vehicles.

Pedestrians and bicyclists create hazards, too. Walkers, joggers, and bicyclists may be on the road with their backs to traffic. These individuals often wear portable headphones so they don't hear oncoming vehicles. In rainy conditions, pedestrians and others may not see vehicles because of hats or umbrellas. Pedestrians are not as visible in rainy conditions, creating a greater danger, especially when combined with increased stopping distances. And with more and more frequency, these highway users are also distracted by devices they operate while walking or peddling, adding to the danger.

Children tend to act quickly and without checking traffic. This is especially true when a group of children is playing and may be unaware of traffic nearby. Be especially careful in school zones and near cross walks, school buses, parks, and ice cream trucks.

Collisions create a rich environment for subsequent or secondary collisions. People involved in the crash may not look for traffic. Passing drivers are distracted by the accident, and emergency vehicles and police may be attempting to get to the site. Debris may be present on the roadway, as well as spilled fuel that can be extremely hazardous.

Confused drivers often change direction suddenly or stop without warning. Confusion is common near freeway or turnpike interchanges, major intersections, and work zones. Tourist areas are dangerous for this reason, and also for the number of pedestrians, including children, who may be present. Shoppers are focused on finding stores rather than traffic flow, and shopping areas frequently have a high traffic volume. Clues to identifying tourists include car-top luggage and out-of-State license plates. Drivers who are confused are often looking at street signs, maps, and house numbers rather than surrounding traffic. Also, drivers signaling a turn may be hazardous, regardless of location.

Slow drivers are also hazards. Seeing far enough ahead is critical to react adequately to slow-moving vehicles. Some vehicles, including many oversize loads, are, by their nature, slow. Drivers in a hurry create even greater hazards in this context. Drivers may pass without a safe gap, may cut too close in front of other vehicles, and may demonstrate aggressive behavior. Be aware of these drivers and make every attempt to get out of their way and let them pass.

Impaired drivers include fatigued drivers; those who have consumed alcohol, prescription drugs, over-the-counter medications, or illicit drugs; and drivers experiencing medical problems, among other impairments. Weaving, dropping right wheels onto the shoulder or bumping across curbs or median dividers, drifting onto the rumble strip, stopping at a green light or waiting too long at a stop sign, speeding up or slowing down suddenly, and driving at night without headlights are typical behaviors of impaired drivers. For more information about distractions, fatigue, drowsy driving and other impairments, see Module 7.

Drug Impairment

Laws prohibit possession or use of many drugs while driving (and rules for alcohol and drugs are more stringent for holders of commercial driver's licenses (CDL) than for individuals with a regular operator's license). Drivers are prohibited in every State from being under the influence of any controlled substance, narcotics, or any other substance that impairs driving ability. This includes a variety of prescription and over-the-counter medications.

Certain types of medication are especially dangerous. These include cold and flu medications that often contain substantial amounts of alcohol and allergy medications that frequently produce pronounced drowsiness. Alcohol can make the effects of these and other drugs more intense, or in some cases, negate the effects of medications.93

Drivers must pay attention to warning labels and to doctor's instructions. It is important to take a new medication on a day when no driving is required to determine its effects. With some medications, more time may be needed; i.e., to give a drug time to build up in the bloodstream. Drivers should monitor their own behavior as new medications begin to take full effect.

Avoid both drugs that mask fatigue as well as excessive use of caffeine to stay awake. Over-caffeinated drivers can behave erratically and often drive aggressively. The only cure for fatigue is rest.

Drowsy drivers are more dangerous than individuals realize. P/EVOs are not currently subject to hours-of-service rules and are not required to maintain logbooks. However, incidents that occur while moving oversize loads are often found to have involved fatigued drivers. See Module 7, Lesson 2 for more information about the dangers of fatigue and drowsy driving. Federal hours of service (HOS) rules for load drivers are found at 49 CFR 395, and the Federal Motor Carrier Safety Administration (FMCSA) provides an "Hours-of-Service (HOS) Regulations – Comparison"" visor card that addresses HOS regulations.94

It is important during the pre-trip planning process to include plans for adequate rest. Plans for load movement must accommodate the team members' need for rest as a matter of safety. Fatigue can be deadly, and the only adequate remedy for fatigue is sleep.

Tests have shown that after being awake for 18 hours, drivers score no better on driving skill tests than drivers with a blood alcohol concentration of .05 percent. After being awake for 24 hours, the driver's skill is reduced to that demonstrated by drivers at the .10 blood alcohol concentration. Planning for rest is as important as any other plans made for moving loads safely.


  1. What are the primary functions of the rear P/EVO?
  2. What is meant by the term "offtracking?"
  3. How does being top-heavy (having a high center-of-gravity) affect the maneuverability of the load?
  4. What is the primary hazard a load with low ground clearance encounters?
  5. How do the driving abilities of drowsy drivers and drinking drivers compare?


The focus of this lesson is on information about how and when to use the required equipment covered in Module 2, Lesson 2. Each State has its own requirements for P/EVO equipment, so it is important for the P/EVO to know what each State requires. It is also useful to review, from time to time, regulations at 49 CFR 393.95 for information about emergency equipment requirements, and the Manual on Uniform Traffic Control Devices (MUTCD) for flagging and flagger equipment standards and guidance.

The focus of this lesson is on devices and equipment related to traffic control operations—STOP/SLOW paddle, hardhat, safety vest, emergency flag, fire extinguisher(s), communication equipment, emergency warning devices (cones, reflective triangles, flares), lights, flags, and signs—that are typically required. It is important to remember that not all States require the same equipment, nor do State rules align in terms of when and how certain equipment is to be used. States vary in the authority given to P/EVOs to control traffic. For example, many States allow P/EVOs to control traffic, and others allow it only if the P/EVO is also a certified flagger.

Flagging Equipment

Hardhats and Safety Vests.95Type II hardhats, as described in Module 2, Lesson 2, are recommended for P/EVOs. Safety vests for flaggers, as specified in the Manual on Uniform Traffic Control Devices (MUTCD)96 and American National Standards Institute Standard 107-2015, must be fluorescent orange-red, fluorescent yellow-green, or a combination of the two with retro-reflective material visible at 1,000 feet.

STOP/SLOW Paddle.97 Most States require P/EVOs carry at least one 18-inch STOP/SLOW paddle. The paddle should have a retroreflective surface and be standard in color and shape (i.e., octagonal shape). The "stop" side must be red with white letters, and the "slow" side must be orange with black letters. The minimum size is 18 inches with 6-inch letters; however, when controlling traffic at highway speeds, a 24-inch paddle is recommended. It is also recommended that P/EVOs have an extra STOP/SLOW paddle; because most collisions happen at intersections, traffic may need to be controlled in several directions. In these situations, the load driver may need to help with traffic control, and load drivers are not currently required to carry a STOP/SLOW paddle. The P/EVO should have a pole about 7-feet tall for mounting the STOP/SLOW paddle when traffic control will be needed for more than a few minutes. Standard traffic signs are installed so that the bottom of the sign is 7 feet above the ground (as specified in the MUTCD). By having a pole this length, the STOP/SLOW paddle will be at the height drivers are accustomed to seeing road signs.

As mentioned in Module 2, Lesson 3, the STOP/SLOW paddle may be modified to improve conspicuity by incorporating either white or red flashing lights on the STOP face, and either white or yellow flashing lights on the SLOW face. The flashing lights may be arranged in any of the several patterns. See the MUTCD, Section 6E.03, for details on light placement and other specifications.

In addition to the STOP/SLOW paddle(s), many States also require P/EVOs carry a 24-inch by 24-inch red flag (or red-orange or fluorescent versions of those colors) for controlling traffic in an emergency only when no STOP/SLOW paddle is available.

Flashlight. Some States require a flashlight with a cone (traffic wand) attached. For this reason, it is a good idea to have a large flashlight with a safety nose cone along with extra replacement batteries and bulbs. The flashlight should be durable, water resistant, have a non-slip handle, and be appropriate for roadside operations day or night. Even if the P/EVO is escorting a load that moves only daylight to dark, this doesn't mean the P/EVO won't be flagging traffic after dark, especially in the event that the load becomes disabled.

Emergency Equipment

Fire Extinguisher(s).98 The P/EVO should read all instructions and warnings for the extinguisher (before the trip begins). All members of the load movement team must know how to use the extinguishers and where they are located in each vehicle.99

If no hazardous materials are being transported, P/EVOs should have extinguishers with an Underwriters' Laboratories (UL) rating of 5 B:C or more or two fire extinguishers, each with a rating of 4 B:C or more. Each fire extinguisher must be labeled or marked by the manufacturer with its UL rating, and must be designed, constructed, and maintained so that visual determination of whether the extinguisher is fully charged or not is possible.

The fire extinguisher(s) must be filled and located so they are readily accessible. Many States require the extinguisher(s) to be securely mounted to prevent sliding, rolling, or vertical movement relative to the motor vehicle. Finally, fire extinguishers must use an extinguishing agent that does not need protection from freezing, and extinguishing agents must comply with the toxicity provisions of the Environmental Protection Agency's Significant New Alternatives Policy regulations.100 It is also recommended the extinguishers be shaken frequently to avoid settling and packing of the extinguishing agent, which occurs due to normal vehicle vibration while driving.

Warning Devices: Flares, Cones, and Reflectors. States vary in what they require for warning devices. Some require flares, and chemical flares are strongly recommended, especially in areas where wildfires are a concern. Others require triangle reflectors (a minimum of three; some States require more) and still others require cones of various sizes. It is the responsibility of the P/EVO to know what is required by each State. When flagging, it is a good idea to put a cone or reflector in the lane being controlled by the flagger, and/or between the flagger and the first stopped vehicle. This lets motorists know exactly where the P/EVO want drivers to stop, and provides an extra measure of safety for the P/EVO controlling traffic.

Placement of Warning Devices. When a load vehicle is stopped on the traveled portion of the shoulder of a highway, as soon as possible (and certainly within 10 minutes), the driver should place required warning devices in the following manner on multilane highways as specified in the American Association of Motor Vehicle Administrators Model Commercial Driver License Manual:101

  1. One warning device (triangle reflector, flare, or cone) on the traffic side and 4 paces (approximately 3 meters or 10 feet) from the stopped commercial motor vehicle in the direction of approaching traffic.
  2. A second warning device at 40 paces (approximately 30 meters or 100 feet) from the stopped commercial motor vehicle in the center of the traffic lane or shoulder occupied by the vehicle and in the direction of approaching traffic.
  3. A third warning device at 40 paces (approximately 30 meters or 100 feet) from the second device (approximately 210 feet from the vehicle) and in the direction of approaching traffic.
  4. The STOP/SLOW paddle should never be left unattended (propped on equipment or stuck in a safety cone, for example).

If fusees (flares that burn brightly in wet or dry conditions) or liquid-burning flares are used, the P/EVOs or the load driver should place at least one fusee or flare at each of the locations as specified in the preceding paragraph. These must remain in place and visible as long as the load is stopped. Before the load is moved, the driver(s) must extinguish and remove all fusees or liquid-burning flares.

Pilot/Escort Vehicle Operator Special Skills

Height Pole Operation

When loads are tall, the lead P/EVO should (or as required by the State) use a height pole. State requirements vary, but if a height pole is required it is typically specified on the permit. Height pole operation is designed to prevent the load from hitting bridges, power and utility lines, signs, traffic lights, and other primarily overhead obstructions. In many States, a load is considered over-height if it is taller than 13 feet 6 inches. States also differ about when a height pole must be used and the way it must be calibrated.

The height pole should (or as required by the State) be made of a non-conductive, non-destructive flexible material and should (or as required by the State) be securely mounted on the escort vehicle in order to avoid creating a hazard to surrounding motorists and vehicles, transportation infrastructure, the escort vehicles, or the load vehicle. The height pole is mounted on the front of the lead escort vehicle and must be calibrated as described below.

The P/EVO operating the height pole must have an unobstructed view of the pole and must be far enough ahead of the load to be able to communicate to the load driver in enough time to get the load stopped before striking any overhead obstruction.


States vary in what they require102 when installing the height pole; established best practice is that all height poles should be, at a minimum, set 3 to 6 inches above the tallest part of the load.103 Measure the load and set the height pole, with the assistance of the load driver. Confirm the height with the load driver.


A tillerman or steerman is an individual who steers any axle of an articulated trailer. In 2011, the Federal Motor Carrier Safety Administration (FMCSA) provided regulatory guidance104 on the applicability of the definition of a "driver" to "tillerman," a person exercising control over the movement of a steerable rear axle on a commercial motor vehicle. The agency had previously determined that although a tillerman does not control the vehicle's speed or braking, the rear-axle steering he or she performs is essential to prevent the trailer from offtracking into other lanes or vehicles or going off the highway entirely, and because this function is critical to the safe operation of vehicles with steerable rear axles, the tillerman had been defined as a "driver" and thus is subject to commercial motor vehicle (CMV) regulations.

However, FMCSA has more recently concluded the person operating the steerable rear axle should be classified as a "tillerman." CDL knowledge and skills testing would have little relevance to the remote-control operation of a steerable rear axle on an oversized vehicle. FMCSA said it considers the tillerman's physical location in, on, or around a CMV to be the most relevant factor in determining whether the person is a driver, and that anyone controlling a steerable rear axle from outside the CMV would be doing so under the direction of the person in the cab, and therefore should not be considered a driver.105 (See 49 CFR Parts 383 and 390 for clarification.)

As with most other P/EVO regulations, it is necessary to check with the State agency that oversees oversize load permits and P/EVO operations to find out what the rules are regarding steering articulated trailers. It is not recommended, and is unlawful in many States, for a single individual to perform two driving tasks simultaneously; that is, functioning as both the P/EVO and the tillerman at the same time. This is true in some States regardless of how the trailer is steered. Further, in many States, a tillerman/steerman must have a Class A CDL. (See 49 CFR Parts 383 and 390 for clarification of Federal rules. Check with each State for additional rules.)


  1. Where should warning devices be placed in vehicle breakdown or other roadside emergency situations?
  2. What is the function of a height pole?
  3. How are height poles calibrated?
  4. What is a tillerman and what does he/she do?


State permits typically specify how many escorts are required for a given over-dimensional load. However, no specific laws or rules exist about how far the P/EVO should be from the load, where the escort should be when passing other vehicles, operating in urban versus rural environments, or other particular situations.

Because of the prototypical nature of the job, specific rules are not possible. Each situation requires the load movement team to adjust to current conditions and the limitations of the load. For example, there are few if any rules that establish in actual feet the distance P/EVOs should be from the oversize load vehicle. This decision should be made in light of the situation rather than a rule. For example, factors affecting safe distance from the load include weather conditions, night or day, volume of traffic, features of the terrain, and the size and configuration of the load. Rules are necessarily non-specific in order to provide latitude for the load movement team to appropriately and safely adjust procedures to conditions.

The P/EVO is responsible for warning motorists of the presence of an oversize load, flagging traffic when necessary and allowed, and helping the load driver negotiate obstructions and successfully complete challenging maneuvers.

The number of P/EVOs required for a particular load varies from State to State; however, some similarities exist. It is the State permit, ultimately, that determines the minimum number of P/EVOs required and where they are to be positioned in relationship to the load during movement. It should be noted that, as is the case with State laws, requirements set forth on the permit (or in laws) are minimum standards. The carrier or the owner of the load itself may provide more P/EVOs than required by permitting officials.

The following provisions are consistent with laws in many States:106

  • Loads in excess of 12-feet wide require one P/EVO in front of the load on two-lane roadways and one P/EVO behind the load on multi-lane roads.
  • Loads in excess of 14-feet wide often require two P/EVOs—one in front and one behind on all roadways.
  • Loads in excess of 90-feet long commonly require one P/EVO behind the load.
  • Loads in excess of 150-feet long require two P/EVOs, one in front and one behind the load.
  • Loads in excess of 14-feet 6-inches tall require at a minimum one P/EVO in front of the load, and that P/EVO must have a height pole in place.

Of course, many loads may exceed more than one dimension, so these are basic similarities only. As mentioned, it is the permit that specifies the minimum standards in terms of the number of P/EVOs.

Pilot/Escort Vehicle Operator Positions

Not only do the rules about P/EVOs being in front of or behind the load vary from State to State, the exact placement of the P/EVO also varies depending on traffic speed, traffic volume, type of roadway, number of lanes, and, of course, the size of the load. It is very important for every member of the team to be familiar with the permitted route, permit restrictions, and the route survey. However, it is vital for the lead P/EVO to know the route in order to notify the team of hazards, both expected and unexpected, and to keep the team informed about upcoming turns, exits, or hazards.

Distance From The Load

Guidelines and rules also vary from State to State when it comes to the distance between the P/EVO and the load vehicle. In general, distances must be increased, especially between the load and the lead P/EVO, due to the size and weight of the load. Properly estimating stopping distance is crucial in determining the safe vehicle spacing between the P/EVOs and the load vehicle, as well as the space between the load movement team and all other highway users.

The P/EVO must be located a safe distance from the load while also giving the traveling public maximum warning. In normal conditions, the front P/EVO should be 4 seconds ahead of the load, or 1 second for each 10 feet (or portion of 10 feet) of load length. Another second should be added when the load moves at 40 mph or more. The rear P/EVO should be 3 to 4 seconds behind the load. Distances should be adjusted for nighttime travel, rainy conditions, and other potential hazards that negatively affect visibility, traction, or braking. However, the distance should not exceed ½ mile in order to stay within radio range.

The lead P/EVO must be far enough ahead of the load to give the load driver ample time to take action when obstacles or hazards are encountered. All drivers face two sometimes life-altering choices when confronting an obstruction: to stop before hitting it or to steer around it. Both of these choices take much longer to execute in an oversize load vehicle. While it is impossible to consider every potential situation, some common scenarios are described below.

Passing a Slower Vehicle. First, if there is a front escort only, the P/EVO and load driver should communicate the intention to pass a slow-moving vehicle. The P/EVO and load driver should consider speed and clearance to ensure the passing maneuver can be made safely. If there is only a rear escort, once the intention to pass is communicated, the rear escort driver moves into the passing lane, then the load passes the slow-moving vehicle. The P/EVO should alert the load driver when it is safe to move the load back into the right lane once the load is a safe distance in front of the vehicle(s) just passed. The rear P/EVO then completes the pass and moves back into the right lane.

Restricted Visibility. When traveling through terrain with blind curves, hills, and other conditions of restricted visibility, it is important to adjust vehicle spacing to ensure adequate advance warning can be given to motorists and for the load driver to react to problems. If distance between P/EVOs and load vehicle is extended, check radio communication. It is critical that the lead P/EVO be far enough ahead of the load vehicle (i.e., over the hill, around the curve) to allow enough time for motorists and the load driver to react to problems. Reducing the distance between the escort vehicle and the load if communication capability is lost in hilly terrain requires the team to reduce speed overall. This is important to remember about moving through mountainous terrain: the P/EVO must be close enough to the load to remain in communication contact, yet must be far enough ahead (or behind) the load to timely warn motorists of the presence of the oversize load they cannot see.

Merging onto a Multi-Lane Highway. In nearly all situations, if a P/EVO is required for multi-lane highways, he or she will be positioned behind the load. An exception is when the load is tall, and the P/EVO is operating a height pole. For either a rear or front P/EVO, when the load is merging onto a highway, the P/EVO moves onto the highway before the load does. In this way, the P/EVO warns motorists of the presence of the oversize load coming into the right lane.

Negotiating Turns with Long Loads. When turning long loads, it is crucial that the lead P/EVO control traffic, according to relevant jurisdictional rules, to allow the long load to successfully execute the turn by crossing into oncoming lanes.

Once the load has cleared the intersection and has moved back into the normal travel lanes, the lead P/EVO can resume the normal travel position in front of the load. It is also crucial that the rear P/EVO control traffic approaching from the rear to avoid motorists encroaching into the path of the long load, especially motorists who attempt to pass the oversize load on the right.107 Under no circumstances should a flagger stop flagging until the blocked lanes(s) are clear. This is true regardless of whether the P/EVO is controlling traffic behind the load or controlling oncoming lane(s) of traffic.


  1. What determines the number of escorts and their placement relative to the load (that is, front or back)?
  2. Why are many laws and rules governing P/EVOs ambiguous and non-specific?
  3. What should be considered when establishing distance between the P/EVOs and the oversize load vehicle?
  4. What common traffic maneuvers require extra vigilance on the part of P/EVOs?


P/EVOs may be required to flag traffic not only in known, that is, planned situations such as closing a narrow bridge to allow the oversize load to cross, but P/EVOs may also be required to control traffic in emergencies, or unplanned situations such as a vehicle breakdown, or a weather or traffic event that makes load movement unsafe or impossible. Therefore P/EVOs must be prepared to control traffic at any time and in any conditions: night or day, hot or cold, wet or dry, even when the load moves only from daylight to dark.

States require flaggers be at least 18 years old, and some States require P/EVOs and flaggers be at least 21 years old. Each potential flagger should read, in addition to this lesson, at least one flagger handbook, and should review the material in the MUTCD, Part 6, especially the diagrams such as TA-10.108

Table 1. Sample of State rules for traffic control/flagging.
Manual on Uniform Traffic Control Devices (MUTCD) (Federal Standards) None of the dozens of procedure descriptions and illustrations found in the MUTCD depict flaggers inside vehicles.1
Alaska Flag-persons must be at least 18 years old, must wear bright orange jacket or vest, and be equipped with a STOP/SLOW paddle and a red hand flag. These items are to be utilized by the P/EVO in the event that it becomes necessary to park the pilot car and stop or control highway traffic. At no time will the SLOW/STOP paddle and/or red flags be displayed out of the window of a moving vehicle.2
Colorado "When directing traffic . . . [the] Pilot Escort driver shall: Stand outside the Pilot Escort Vehicle.3
Minnesota P/EVOs are "authorized to control and direct traffic as a flagger during the movement of an over-dimensional load following the MUTCD standards as defined by the Federal Highway Administration and Minnesota Statutes, Section 169.06, Subdivision 4.4
Oklahoma "In the performance of duties as the operator of an escort vehicle, the operator is authorized to direct traffic to stop, slow down or proceed in situations where such direction is necessary to allow traffic or the escorted vehicle or load to continue moving safely." The only place P/EVOs are not authorized to control traffic in Oklahoma is an intersection with a working traffic light.5
1 Federal Highway Administration, Manual on Uniform Traffic Control Devices, 2009 Edition. Available at:
2 Alaska Department of Natural Resources, Administrative Permit Manual, Oversize and Overweight Permits, Section  12,  p.  22.
3 Code of Colorado Regulations 2 CCR 601-4 p. 26
4 2015 Minnesota Statutes, Chapter 169. Traffic Regulations, "Section 169.06 Signs, Signals, Markings." Available  at:
5 Oklahoma Administrative Code, 595:30-3-17(e)(1).

Information about equipment and procedures for controlling traffic is found in the MUTCD. Temporary traffic control (TTC) is the type of flagging typically performed by P/EVOs in States that allow it. If P/EVOs are not allowed to flag traffic in a specific jurisdiction, this task typically falls to law enforcement officials. It is important that P/EVOs understand and acknowledge the role of law enforcement officers in this context—when law enforcement officers are on the scene, they are in charge.

Table 2. Hierarchy of traffic control personnel.
Carrier/Permittee Hires pilot/escort vehicle operators (P/EVO) and flaggers
P/EVO Control traffic in jurisdictions that allow it
Law Enforcement Escorts When required, law enforcement escorts are in charge of traffic control operations when present

TTC is particularly dangerous, in part because the flagger does not have advantages typically found in other traffic control situations such as construction work zones. For P/EVOs, there are no advance warning signs (Flagger Ahead, or One-Lane- Road signs, for example). TTC zones "present constantly changing conditions that are unexpected by the road user. This creates an even higher degree of vulnerability for the workers and incident management responders on or near the roadway."109 The lack of advance warning devices combined with the unpredictability inherent in moving oversize loads produce a potentially dangerous situation.

For these reasons, it is vital the flagger be positioned so that he or she will be seen by motorists. Several factors affect where the flagger should be located. First, how fast is traffic moving? The P/EVO must consider stopping distances based on how heavy a vehicle is, how fast it is moving, whether it is on a down slope or not, whether the roadway is gravel or asphalt, wet or dry. When considering the position for the flagger, consider how long it will take for the largest, heaviest, fastest moving vehicle that may approach the flagger to stop, and place the flagger in a position that allows adequate stopping distance for that vehicle.

The flagger must display the STOP/SLOW paddle in the place drivers typically see signs. This is an important example of standardization that enhances safety for the motoring public and the load movement team. Motorists do not look for stop signs in moving vehicles. Flagging traffic involves getting out of the vehicle.

It is never appropriate to attempt to control traffic by parking a vehicle across lanes of traffic, especially at highway speeds. This behavior is exceedingly dangerous and irresponsible. One of the first rules new drivers are taught is to never, ever stop in a roadway.

Flaggers must be in the standard position (right shoulder of lane being controlled) with standard equipment (STOP/SLOW paddle), at the standard height (7-foot pole) and wearing standard safety gear (hardhat, safety vest) to control traffic safely.

How far should the flagger be ahead of the activity area or disabled load? Decision sight distance and other considerations are significant to safely positioning the flagger. Decision sight distance is the total distance traveled during the time required for a driver to:

  • Detect an unexpected or otherwise difficult-to-perceive information source or hazard in a roadway environment that may be visually cluttered.
  • Recognize the hazard or its potential threat.
  • Select an appropriate speed and path.
  • Initiate and complete the required maneuver safely and efficiently.110

Conditions to be considered when deciding where to place a flagger include how fast traffic is moving, features of the terrain, and the condition and type of roadway surface. Other considerations include weather, darkness, and traffic volume.

Equipment for Controlling Traffic

As with most aspects of pilot/escort operations, States vary in the traffic control equipment required. However, the STOP/SLOW paddle, a 24-inch by 24-inch red flag, a radio, and retroreflective safety vest are required in nearly all States.

For controlling traffic, as described in more detail in Module 2, Lesson 2, most States require an 18- inch STOP/SLOW paddle (minimum size) with reflective surface. Some States require two paddles, given that most incidents happen at intersections where traffic in more than one direction may need to be controlled. It is also advisable to have a 24-inch STOP/SLOW paddle for higher speed roadways, where traffic is moving at more than 60 mph as drivers are more likely to see a larger paddle at higher speeds. A 7-foot pole for mounting the STOP/SLOW paddle should be available when traffic needs to be controlled for longer than 10 to 15 minutes. Some States require the P/EVO carry an extra paddle because load drivers are not required to carry one, and most collisions happen at intersections where more than one lane of traffic may need to be controlled, as mentioned.

Most States require P/EVOs wear a safety vest with retro-reflective material, yellow, orange, yellow green, or a fluorescent variation of these same colors for enhanced visibility during daytime and nighttime operations. It is important to remember that it may not be in the plans to control traffic after dark. If a load becomes disabled, it is likely the P/EVO will remain with the load vehicle until   it is repaired or towed. Safety clothing should be provided for every adult in the escort vehicle, in those States that allow passengers, in the case of an emergency. A hardhat is required for P/EVOs in most States. A yellow green, orange, or fluorescent yellow green hardhat increases visibility to approaching traffic.111

A two-way radio compatible with those of other team members, including other flaggers and the load driver, is required. Some States (Alaska, for example) actually require the use of CB radios. Alaska rules state that radio communication is "required between towing vehicle and pilot car(s)... [and] shall be open and monitored at all times... C.B. radios are the only approved radio communications."112

Cones, flares, and/or reflective triangles are important to mark the spot where the P/EVO wants cars to stop. Placing a cone or reflector between the flagger and oncoming traffic provides another measure of safety and visibility.

Flagging Dos and Don'ts

  • Be alert.
  • Remain standing at all times, facing oncoming traffic.
  • Park vehicles off the road and away from the flagger station.
  • Never turn or look away from oncoming traffic.
  • Never stand in the path of moving traffic.
  • Never stand near or between parked vehicles on the roadside.
  • Nothing should be near the flagger—no devices such as music players or smart phones.
  • No person should be near the flagger.
  • Never stop flagging until the blocked lanes(s) are clear. This is true regardless of whether the P/EVO is controlling traffic behind the load or controlling oncoming lane(s) of traffic.
  • Never lean on vehicles; be polite but brief. Never argue with a motorist.

Additional Traffic Control Issues

If a driver ignores the flagger's instructions, do not stop flagging. First, warn people in the control zone/activity area of the presence of the errant vehicle. Get a description of the vehicle, including the tag number if possible. Finally, report the motorist to authorities.

Flaggers must have frequent breaks (no more than two hours of flagging). The hotter, colder, windier, or wetter the conditions, the more frequently flaggers must have breaks.

It is important for P/EVOs to be aware of traffic conditions at nearby intersections, especially in high-volume intersections or during peak traffic times. It is important that P/EVOs avoid causing potentially dangerous situations, including traffic backups in intersections or on exit and entry ramps, for example. Traffic tie-ups create a rich environment for collisions. Another situation to consider is that when an intersection exists within the activity area, an additional flagger may be needed to control traffic entering from that intersection.

Remember, emergency vehicles have priority. When emergency vehicles approach, flaggers should stop all traffic under their control until the emergency vehicle has cleared the area.

Traffic Control Authority

States also differ in the authority extended to P/EVOs to control traffic. Many States allow it, while others do not. As mentioned, if P/EVOs are not authorized to control traffic in a given jurisdiction, this responsibility is typically delegated to law enforcement officials—and these officials are in charge of the load movement while they are engaged in the process.

As discussed throughout this manual, P/EVOs frequently encounter situations during load movement for which there are no set rules or laws. Case studies, accident investigations, and experience are a source of best practices for typical traffic control situations.


  1. What equipment must flaggers have?
  2. What must flaggers NOT have?
  3. In what situations might P/EVOs be required to control (flag) traffic?
  4. When is it appropriate to control traffic from inside a vehicle?
  5. What does TTC stand for? Why is it dangerous?
  6. When is it appropriate to control traffic by parking a vehicle across lanes of traffic?
  7. What should be considered when deciding where to place a flagger?
  8. How big, according to the MUTCD, are typical stop signs on highways with speed limits of 60 mph or more?
  9. Are P/EVOs authorized to control traffic in all States?


Because railroad crossings and other grade fluctuations present high levels of risk for oversize loads with low ground clearance, P/EVOs must be familiar with the oversize load and its limitations in order to be able to warn highway users and load drivers of problematic crossings. The combination of high-profile crossings and low-clearance vehicles presents great challenges in moving oversize loads.

Railroad tracks are built up to create effective draining. Frequently, abrupt changes in the level of the road surface as the road crosses the tracks increases the risk of low clearance vehicles becoming stuck at the crossing.

All railroad crossing (and other grade changes) should (or as required by the State) be included in the route survey, along with emergency contact numbers for each crossing. This information should be reviewed daily; that is, before starting travel for the day, the load movement team should be reminded of the hazardous crossings on that day's route, and the emergency procedures and contingency plans to be followed if the load should become lodged at a crossing. However, it is important to remember, the decision about whether to traverse a crossing remains with the load driver.

Railroad crossing are extremely hazardous, and a good route survey doesn't change that, of course. Knowing about the crossings does not reduce their potential impact on load movement. The hazards primarily include speed and stopping distance. It can take more than a mile for a train to stop once emergency brakes are applied. In addition, freight trains average a mile in length and travel at 50 to 60 mph and more.113 A 150-car freight train traveling at 50 mph needs 8,000 feet (1.5 miles) to stop; an 8- car passenger train at 79 mph needs about 6,000 feet (1.125 miles) to stop.

Stopping distances for trains is substantially longer primarily because of the weight of the train, but stopping a train includes processes similar to those involved in stopping other vehicles: stopping distance is the sum of perception time, reaction time, brake lag, and braking distance. The contact area between a train's steel wheels and the steel rails is about the size of a dime, producing limited friction that is required to stop a train.114

When an engineer sees an obstruction at a crossing, effectively about a half-mile ahead of the crossing, it is already too late to avoid a collision.

Because the risks, outcomes, and costs of truck/train collisions are so high, a commercial driver can lose his or her CDL for 60 days for a first violation of railroad crossing rules, for at least 120 days for a second violation within a 3-year period, and for at least 1 year for a third violation within a 3-year period. While the P/EVO is not subject to these same rules when driving the escort vehicle, it is important for the P/EVO to understand what the load driver is required to do.

Railroad crossing violations for CDL holders include failing to stop before reaching the crossing if the tracks are not clear, failing to slow down and check that the tracks are clear of an approaching train, failing to come to a complete stop when required to do so, failing to have sufficient space to drive completely through the crossing without stopping, failing to obey a traffic control device or the directions of an enforcement official at a crossing, and failing to negotiate a crossing because of insufficient undercarriage clearance.115

Table 3. Total highway-rail incidents for all States, January to May, 2010 to 2015.
YEAR Number of Incidents
2010 848
2011 815
2012 800
2013 851
2014 974
2015 830
Source: Federal Railroad Administration, Office of Safety Analysis

In 1972, more than 1,500 fatalities and 12,000 accidents occurred. Ten years later, 500 fatalities, and approximately 1,000 accidents occurred. The statistics have remained static since then, in spite of the significant increases in railroad and highway traffic between 1984 and 1994 (remembering this report was published in 1996). In 1994, 615 people were killed and 1,961 were injured in 4,979 collisions with trains at highway-rail crossings.116

A report of a grade crossing safety task force, produced in 1996, identified five areas of safety problems related to railroad crossings: interconnected signals, vehicle storage space, high-profile crossings, light rail transit crossings, and special vehicle operations. Some of these affect oversize loads, as explained in the next section. The task force involved people from Federal Railroad Administration (FRA), FHWA, National Highway Transportation Safety Administration, Federal Transit Administration, American Association of State Highway and Transportation Officials, the Association of American Railroads, and the Institute of Transportation Engineers. The group looked at design, construction, operation, maintenance, and inspection of grade crossings.117

Operation Lifesaver (established at the national level in 1987), is a public education program designed to reduce the number of crashes, deaths, and injuries at highway-rail crossings and on railroad rights-of-way. Operation Lifesaver emphasizes education, engineering, and enforcement, and is funded by FHWA, FRA, and the rail industry.

As with many of the rules affecting P/EVOs, rules and standards for railroads are set at the State level. The regulatory framework as well as the building, maintaining, and inspecting of rail crossings, and controlling the traffic that traverses them, are inconsistent from State to State.118

Oversize Load Issues119

Vehicles with a deep-well or low-boy chassis are used to gain vertical clearance when transporting large loads through tunnels and under bridges. These trailers, however, may not have sufficient ground clearance to traverse high-profile rail crossings or other grade changes. Other vehicles, particularly long loads, may exceed the space available between highway-rail crossings and nearby highway- highway intersections or traffic control devices. This creates a situation where a load may be stuck on the tracks during a red light. These situations must be avoided. A load vehicle should never start across a track or series of tracks unless the load can traverse all the tracks without stopping and without shifting.

Another issue involves signs and warning devices at the crossing that may impede turning movements of oversize loads, especially long ones. Finally, low ground clearance, defined by the Uniform Vehicle Code and Model Traffic Ordinance as equipment with a vertical body or load clearance of less than 9 inches above a level roadway surface, presents substantial challenges during oversize load movement.

Route Survey Issues

When assessing a railroad crossing, it is important to know the ground clearance of the load vehicle. It is critical for the load driver to know when the railroad must be contacted before attempting to move the load over the tracks.

Route surveys should include each railroad crossing along with any potential obstructions and nearby transportation infrastructure. Whether a route survey is conducted or not, the following should be considered:

  • What is the rise (upward slope) of the crossing from the level road approaching the crossing on the ascending edge?
  • What is the drop (downward slope) from the crossing to the level road on the descending edge?
  • What is the length of the top of the crossing, or the number of tracks in the crossing?
  • What is the approach to the crossing? Straight? Turn? Or curve?
  • What is the descent from the crossing? Straight? Turn? Or curve?
  • What are the requirements /instructions for advance notification to the railroad company?

Types of Crossings

Types of crossings include passive and active crossings. A passive crossing does not have any traffic control devices such as a gate. The decision to stop or proceed rests entirely with drivers. Passive crossings typically have yellow circular advance warning signs, pavement markings, and advance warning signs. Active crossings have traffic control devices installed to regulate traffic, including flashing red lights (with or without bells) and gates.

Procedures for Negotiating Railroad Crossings

It is clear how important route surveys and front P/EVOs can be in assisting load drivers in successfully negotiating railroad-highway grade crossings when they cannot be avoided.

The FMCSA recommends the load stop at least 15 feet but not more than 50 feet from the railroad track(s). When stopping, the load driver and P/EVOs should turn on emergency flashers and use pull-out lanes if available. The load driver and the escorts should listen. Turn off fans and turn down the radio. Roll down windows. Look and listen carefully.120

Never allow traffic conditions to trap the load vehicle on the tracks. And, as mentioned, make sure the load can get completely across all tracks before attempting to cross. It takes a typical tractor-trailer about 14 seconds to clear a single track, and more time must be allowed to cross multiple tracks.

Other situations to be alert to are highway traffic signal timing that doesn't accommodate long loads. Finally, load vehicles (and all others) must be at least 6 feet past the rail before stopping, because trains overhang the rail by at least that much.

If the Load Becomes Lodged at a Railroad Crossing

Hanging up on a railroad crossing is a dangerous predicament, and is becoming too common as more very low trailers are manufactured. Lowboy trailers, car carriers, moving vans, and possum-belly livestock trailers are particularly susceptible, as are single-axle tractors pulling a long trailer with its landing gear set to accommodate a tandem-axle tractor.121

If hung at a railroad crossing:

  • Get out of the vehicle and off the tracks immediately. Do not go back onto the tracks for any reason.
  • Move away from the tracks. Move TOWARD an oncoming train, and AWAY from the tracks. When a vehicle is struck by a train, debris moves in the same direction the train is moving.
  • Locate the emergency phone number and the DOT crossing identification number located near the intersection. (See illustration below.)
  • Call for help. Call the railroad's emergency phone number, the local police, and/or 911. Note: call the local police or 911 if you cannot locate the railroad emergency phone number at the site. This information for each railroad crossing on the route should be included in the route survey.
  • Call 911. Describe the situation and the exact location. Ask them to notify the railroad and assist on site as soon as possible.
  • If a train approaches, move as far as possible from the track(s).122

Detailed plans about the response of each individual team member if the load becomes lodged at the crossing must be set out during the pre-trip meeting. Every member of the team must know how to find the emergency contact information for railroads and what his or her exact responsibility is if this hazard becomes an emergency. P/EVOs should assist local law enforcement in controlling traffic until the issues are resolved and the load is safely off the tracks.

Railroad Crossing Safety Reminders

Based on safety information from Operation Lifesaver, FMCSA, American Association of Motor Vehicle Administrators, and others, P/EVOs must keep the following things in mind when the designated route includes railroad crossings.

  • Never race a train to a crossing.123 Slow down when approaching a crossing in case a train is present. Be prepared to stop at the first railroad warning sign, at least 15 feet from the crossing.
  • Look up and down the tracks. It is difficult to judge the distance and approach speed of a train. If in doubt, be safe, stop, and wait.
  • Keep your rear in the clear. Trains are wider than the tracks, typically 6 feet beyond the rail. Be sure to leave some "living" room.124
  • If it won't fit, don't commit. FMCSA states, "Do not enter a crossing unless you can drive completely though without stopping." Further, because trains are wider than the track, there must be enough room on the other side for the back of the truck and any overhanging cargo to avoid stopping until the load is 6 feet past the last rail at the crossing.125
  • Don'texpect to hear a train. In part, this is due to the noise inside the vehicle, and/or the sounds of the engine. Don't rely on the signals. Do not rely on the train whistle. Noise inside the vehicle may be too loud to hear the warning.
  • A full stop is required for certain vehicles and cargo, especially hazardous materials and tankers. When stopping be sure to watch traffic from behind, and turn on emergency flashers when stopping to reduce the likelihood of being struck from behind.
  • Be especially alert at passive crossings—those that do not have gates or flashing red signal lights.
  • Remember that multiple tracks require multiple checks; a train on one track may hide a train on another track.
  • Be cautious for obstructions that may block the view of an approaching train—vegetation, buildings, standing railcars, etc.
  • It is crucial that the load be able to cross all tracks without changing gears, braking, or stopping.126 FMCSA recommends the load driver keep moving, once starting over the tracks, even if lights start flashing and the gates come down. Make sure any traffic lights or stop signs are far enough past the tracks to allow the load to completely cross and be an adequate distance from the tracks before stopping.
  • Expect a train on any track at any time. Each crossing must be approached with the expectation that a train is coming.127
  • Be alert to weather and how it affects conditions at the crossings, such as impaired vision and substantially increased stopping distances for not only highway traffic, but also the train.
  • Recognize that in certain areas and at certain times, trains may have several hundred passengers on them.
  • Print the FMCSA's railroad safety visor card and put one in every escort vehicle and the load vehicle(s). Mention the rules and hazards of any crossings anticipated for that day at daily pre-trip meetings, and review the contingency plans. Verify contact information for notifying railroads of emergency situations. And it is important to realize that in some situations railroads must be notified immediately before the load crosses the tracks. In these cases, it is important for the P/EVO to assist the load driver in finding a safe area to stop while making any required notifications.
  • Be sure to check emergency numbers and update as needed. Make sure to gather both local and nationwide emergency response numbers. In the case of railroads, it is important to know which company owns and/or maintains a particular crossing. Emergency numbers for eight major railroads are available at:


  1. When escorting a load with low ground clearance, what must P/EVOs do daily?
  2. How long does it take a train to stop?
  3. What railroad crossing violations exist for CDL holders?
  4. What information about railroad crossings should be included in a route survey?
  5. What are two types of railroad crossings?
  6. Where should the load stop in relation to the tracks? How does this affect where the P/EVOs should be?
  7. What must be done if a load becomes lodged at a railroad crossing?


Emergencies have several common characteristics:

  1. An emergency is unexpected.
  2. An emergency threatens a population.
  3. Threats may be real or possible.
  4. Emergencies demand a rapid, sometimes immediate, response.
  5. Responses may reduce or enhance an emergency.

It is also useful to consider what an emergency is not. An emergency is not the same as risk. Risk is exposure to the possibility of physical injury, damage, financial loss or gain, or delay as a result of uncertainty associated with taking a specific action.128 Risk is the probability of an event and is mitigated by maintaining insurance policies, carrying spare parts, and performing other acts of preparedness.

When it comes to oversize load movement, emergencies span a range of possibilities. Traffic emergencies involve vehicles that collide with other vehicles, transportation infrastructure, or obstacles in the roadway. Vehicle emergencies occur when tires, brakes, or other parts of the vehicle, the load, or load securement devices fail during operation. Another form of emergency especially relevant to the movement of oversize loads is roadside breakdown. In many situations, it isn't possible to get the oversize load completely off the roadway. This presents hazards to motorists, especially when traveling at night, during heavy traffic, or in bad weather or low visibility situations. Crashes create emergencies, and the choices made by P/EVOs and load drivers contribute substantially to the outcomes of emergency situations.129

Traffic Emergencies

Drivers have two choices when facing a collision: stop or steer. Chances of avoiding a crash depend on how well a driver responds in an emergency situation.

Vehicles cannot be steered or stopped unless there is traction. Traction is friction between the tires and the road. Some road conditions reduce traction and, therefore, require lower speeds to accommodate longer stopping distances.

Stopping to Avoid a Crash

The lead P/EVO must help prevent the need for emergency stops/braking. And the rear P/EVO needs to be prepared to keep other vehicles away if the oversize load driver must use hard braking or attempt a sudden steering maneuver. The P/EVO must learn to anticipate skids and jackknife situations and protect motorists approaching a load that is out of control.130

Above all, learn from experience and share what you have learned. Use and share all that you learn, especially when dealing with emergencies. This can do more to prevent future emergencies than any other strategy. Create an open climate, a safe place to discuss how load movement can be safer.

Any time the brakes are applied hard, watch the trailer to make sure it is staying where it should be. If the trailer swings out of the lane, it is very difficult to prevent a jackknife. It is vital that the rear escort prevent other motorists from driving alongside a skidding vehicle. Braking can cause a loss of control, even with anti-lock brakes. Avoid turning while braking, as this also increases the chance of producing a skid situation in all types of vehicles.

A Note about Anti-lock Brakes. Anti-lock brakes (ABS) keep wheels from locking up during hard braking. ABS does not produce shorter braking distances, but does help the driver better control the vehicle during hard braking. ABS systems are required on most commercial vehicles with gross vehicle weight rating of 10,000 pounds or more. Trucks and trailers typically have yellow ABS malfunction lamps on the instrument panel and trailers will have a yellow lamp on the left side on either the front or rear corner, typically.

ABS will not allow drivers to go faster, follow more closely, or drive less carefully. ABS will not prevent power or turning skids. While ABS should prevent brake- induced skids, it will not compensate for bad brakes, poor maintenance, or a lack of driver vigilance.131

Steering to Avoid a Crash

Stopping is not always the safest thing to do in an emergency. When a driver does not have enough room to stop, steering away from obstacles is frequently the best option. It is nearly always the case that drivers can steer to miss an obstacle more quickly than they can stop the vehicle. It is important to note, however, that top- heavy vehicles and tractors with multiple trailers may flip over as a result of a sudden change in direction. The lead P/EVO must alert load drivers immediately about objects in the roadway.132 Taking into account the clearance the load requires, in addition to the primary function of warning motorists of the presence of the oversize load, the lead P/EVO must watch for tree limbs, mailboxes, stalled vehicles, etc. It is also critical for the P/EVO to know the size of the gap needed for the load to accelerate and merge with traffic and other limitations of the oversize load vehicle in terms of maneuverability.

Keep both hands on the steering wheel. In order to steer quickly, a firm grip on the steering wheel is necessary. A quick turn can be made safely, even by the load vehicle, if done correctly. First, do not apply the brakes when turning. Wheels are easily locked when braking, and this may produce a skid when turning. Do not turn any more than needed to clear whatever is in the way. The sharper the turn, the greater the chance of skid or rollover. Finally, be prepared to countersteer; that is, to turn the wheel back in the other direction once the obstacle has been cleared. Think of steering and countersteering as two parts of the same action.

If a vehicle drifts into an occupied lane, drivers should move to the right. Vigilant drivers use mirrors to monitor which lanes are empty. If the shoulder is clear, drivers can move in that direction to avoid colliding with another vehicle. If blocked on both sides, moving to the right is advisable, so that other vehicles won't be forced into opposing traffic.

In some emergencies, drivers may have to drive off the road to avoid a collision. Most shoulders are strong enough to support the weight of a large vehicle. Lack of shoulders and inadequate shoulders should be included on the route survey. If a driver must leave the roadway, follow these guidelines:

  1. Take foot off accelerator, but do not brake until speed has dropped. Then brake very gently to avoid skidding, especially if driving onto on a loose surface like gravel or dirt.
  2. Keep two wheels on the pavement to help maintain control of the vehicle.
  3. Stay on the shoulder if it is clear.
  4. When re-entering the road surface, ease onto the roadway gradually when the lane is clear.133


If a crash occurs, actions must be taken immediately to prevent further damage or injury. The priorities are to protect the area, notify authorities, and care for the injured. The first thing to do at the scene of a collision is to prevent another collision. Turn on emergency flashers. Put on a safety vest, hardhat, and take a radio and flashlight and/or STOP/SLOW paddle.

Try to get the vehicles involved to the side of the road. If stopping to help, park away from the accident. Put on emergency flashers and set out reflective triangles and/or flares to alert other drivers especially in hilly, curvy terrain, and at night.

Vehicle Emergencies

Brake Failure

Brake failure is rare, but steep grades can produce an emergency for the load driver and, therefore, the load movement team and nearby motorists. When a brake pedal goes to the floor without results, it is crucial for the driver (whether it is the load driver or a P/EVO) to notify the rest of the team. If it is the load vehicle whose brakes fail, P/EVOs must be alert and do whatever they can to keep motorists a safe distance from the load. Driving an appropriate speed and braking properly are methods for preventing brake failure on long downgrades. However, once the brakes fail, something outside the vehicle will be required to stop it. The best option is an escape ramp which should be part of the route survey and revisited at the daily briefing. If a ramp is not available, look for a place for the driver to turn uphill.

If the vehicle is near a curb when brakes fail, the driver can steer the vehicle so that the tires and wheels rub against the curb to help slow the vehicle. In this case the rear P/EVO must alert approaching drivers to the hazard as the affected vehicle reduces speed. Turn on emergency flashers.

The load movement team must have contingency plans for brake failure long before the emergency happens134 because during the emergency, the P/EVO must focus on protecting the public. If an effective contingency plan is in place, positive outcomes are more likely. And remember, if a collision cannot be avoided, every degree off center that a vehicle impacts an obstacle reduces force on the body of the driver and passengers exponentially.

Tire Failure

P/EVOs must learn to recognize tire failure and how it affects the oversize load vehicle. The bang of a tire blowout, the vibration of the vehicle, and, for the load driver, the feel of the steering wheel, indicate a tire problem. Failure of a rear tire on the load vehicle may produce fishtailing, so it is important during the emergency event for the rear P/EVO to protect highway users by making every attempt to keep other vehicles from pulling alongside the oversize load.

With respect to the escort vehicle, when a tire fails, P/EVOs should hold the steering wheel firmly. Failure of a front tire can twist the steering wheel out of a driver's hands, so holding the wheel firmly at the 8 o'clock and 4 o'clock positions (or lower) is critical. Next, avoid braking as it can cause a loss of control. Unless the vehicle is in danger of colliding with something, stay off the brake until the vehicle is moving more slowly. Then brake very gently and ease off the roadway.135

Skid Control and Recovery

A skid happens whenever tires lose their grip on the road. The earliest and best way for a load driver to recognize that the trailer has started to skid is by seeing it in the mirrors.136 However, the rear P/EVO can also monitor and alert the load drivers.

Skids are caused by over-braking, over-steering, over-acceleration, and driving too fast. Over-braking locks up the wheels, producing a skid. Over-steering (turning the wheels more sharply than the vehicle can turn) will often produce a skid. Over- acceleration (supplying too much power to drive wheels) causes tires to spin. And most serious skids result from driving too fast for road conditions. Excessive speed produces situations in which drivers attempt to correct a movement of the vehicle by over-steering and over-braking, further contributing to skids.

Drive-wheel skids are the most common type. The rear wheels lose traction through excessive braking or acceleration. Skids caused by acceleration typically happen on ice or snow. The driver should take his or her foot off the accelerator. Rear wheel braking skids occur when the rear drive wheels lock. Locked wheels have less traction than rolling wheels, so the rear wheels usually slide sideways. With vehicles towing trailers, a drive-wheel skid means the trailer may push the towing vehicle sideways, causing a sudden jackknife.

Front-wheel skids are typically caused by driving too fast for conditions. Other causes include lack of tread and cargo loaded so that not enough weight is on the front axle. In a front-wheel skid, the front end tends to go straight regardless of how much the steering wheel is turned. The remedy for a front-wheel skid is to let the vehicle slow down. Stop turning and braking and allow the vehicle to slow down.

All commercial drivers should have a precision driving course at least every 5 years and a driver improvement or defensive driving course every 3 years.

There are safety benefits to this training, of course, and frequently insurance rate reductions and liability mediation are also benefits.

Hazardous Materials Emergencies

In the event the load contains hazardous materials and is involved in an incident, if the load driver asks or is unable to report an incident, P/EVOs should be prepared to give:

  • Their name.
  • Name and address of the carrier and load driver.
  • Phone number.
  • Date and time and location of incident.
  • A description of any injuries.

In addition, the P/EVO should know the classification, name, and quantity of hazardous materials involved. Emergency personnel must know whether a danger to life exists or could develop.137

The National Response Center helps coordinate emergency response to chemical hazards. It is a resource used by police and firefighters and has a 24-hour, toll- free telephone hotline. It is vital the load driver and the P/EVOs, if the load driver is unable, are able to report any hazardous materials incident in which: a person is killed, an injured person requires hospitalization, estimated property damage exceeds $50,000, the general public is evacuated for more than 1 hour, or one or more major transportation arteries or facilities are closed for 1 hour or more. In addition, any incident involving fire, breakage, spillage, or suspected radioactive contamination, or contamination involving shipment of etiologic agents (bacteria or toxins, for example), or any situation that involves danger to life or that in the judgment of the carrier, must be reported.

Emergency Roadside Parking/Breakdown

When it is necessary to park on the side of the road, pull off the road as far as possible and immediately turn on the emergency flashers on all vehicles. This is especially important at night. Taillights are not adequate; motorists have crashed into parked vehicles because they perceived the parked vehicle was moving normally. Judging speed and distance at night is difficult. Mountainous terrain enhances these risks.

Before exiting the vehicle, all drivers must put on retro-reflective safety vests (as required by MUTCD 6D.03) and hardhats (as required by the States). Vests should be worn at all times, and the hardhat should be stored in the vehicle within easy reach of the driver. Quickly deploy emergency warning devices (triangles, cones, or flares). Triangles should be placed behind both load and escort vehicles, with one at 10 feet behind the vehicle, another at 100 feet behind, and a third at 200 feet behind the vehicle on one-way or divided highways. If on a two-lane road or undivided highway, place warning devices within 10 feet of the front or rear corners to mark the location of the vehicle, and 100 feet behind and ahead of the vehicle on the shoulder or in the lane the vehicle is occupying. When placing triangles or other warning devices, hold them between you and oncoming traffic to enhance your visibility.

Pay attention to features of the terrain when placing the warning devices to allow fast-moving or heavy vehicles enough time to stop before colliding with any vehicles that may be blocking a roadway or with any emergency vehicles or investigators who may be operating at the scene. If hills and curves are involved, find safe places at the top of hills and at the beginning of curved portions of the roadway to warn traffic in time to stop. Do everything to assure motorists can see the parked vehicle from at least 500 feet, and more in higher speed zones.

Control traffic with the STOP/SLOW paddle when appropriate and lawful. When acting in the capacity of a flagger during an emergency event, the P/EVO must have a sense of responsibility for public safety and adequate training in safe TTC practices (See Lesson 4, above). As with other aspects of load movement, emergency traffic control should be addressed in pre-trip planning and reviewed in detail frequently.138

No roadside operations should be conducted without wearing a retroreflective safety vest.

Fighting Fires

It is important that P/EVOs know how to extinguish fires. Causes of vehicle fires are numerous. After accidents, spilled fuel or improper use of flares may cause a fire. Under-inflated tires and duals that touch may also produce fires. Electrical systems can malfunction, fuel systems may have loose connections, or smokers may be too close to vehicles that are being fueled. Cargo may be flammable, improperly sealed, or poorly ventilated. Any number of situations may produce a vehicle fire.

Avoiding fires starts with the pre-trip inspection. Make certain fire extinguishers are on board and working. En-route inspections should also be performed: check tires, wheels, and vehicle body for signs of heat. Drivers should monitor the instrument panel and gauges for engine overheating. Follow correct safety procedures for fueling the vehicle, using brakes, handling flares, and other activities that can cause a fire. Monitor mirrors for signs of smoke from tires or the vehicle.

All members of the load movement team must study the instructions printed on the extinguishers. Review those instructions regularly. When a fire is detected or suspected, pull off the road immediately, into an open area, away from buildings, trees, brush, other vehicles or anything that might catch fire. Do NOT pull into a service station. Notify emergency services of the problem and location. Do NOT assume someone else has called 911. Keep the fire from spreading before trying to extinguish a fire.

For an engine fire, turn off the engine as soon as possible. Don't open the hood if it can be avoided. Shoot foam through louvers, radiator, and underneath the vehicle. Do NOT crawl under a vehicle in this situation. For a cargo fire in a box trailer, keep the doors shut, especially if the cargo contains hazardous materials. Opening the door(s) will feed the fire with oxygen.

To extinguish the fire, stay as far away from the fire as possible. Aim the fire extinguisher at the base of the fire, not up into the flames. It is important to use the right fire extinguisher for the type of fire encountered.

The B:C type fire extinguisher is for electrical fires and burning liquids. The A:B:C type extinguisher is for burning wood, paper, and cloth as well as electrical fires and burning liquids. Water can be used on wood, paper, or cloth but do NOT use water on an electrical fire (can cause shock) or a gasoline fire (water will spread the flames).

A burning tire must be cooled. Lots of water may be required. If there is doubt about which extinguisher to use or whether or not to use water, wait for firefighters.

Position all persons upwind of the fire; let the wind carry the extinguisher to the fire. Continue until whatever was burning has been cooled. Remember, the absence of smoke or flame does NOT mean the fire won't restart. (See Module 5, Lesson 4 regarding emergency traffic control strategies.)

Injury Issues

If a medically qualified person is at the accident scene and helping the injured, stay out of the way unless asked to assist. Otherwise, don't move an injured people unless they are in danger where they are located (for example, near a vehicle that smells like gasoline) or if the injured person is walking around or lying in a roadway. Keep the injured person as still and calm as possible and contact medical assistance and family members.


  1. What common characteristics do emergencies have?
  2. What two options do drivers have when confronting an obstacle in the roadway?
  3. For P/EVOs, what two types of emergencies are most common?

71 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 35. [ Return to note 71. ]

72 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 6.1.2. Available at: [ Return to note 72. ]

73 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 43. [ Return to note 73. ]

74 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 6-4 and 6-5. Available at: [ Return to note 74. ]

75 Insurance Institute for Highway Safety (IIHS), Fatality Facts web page, "Large Trucks, 2013." Available at: [ Return to note 75. ]

76 Ibid. [ Return to note 76. ]

77 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 36-37. [ Return to note 77. ]

78 TWIC cards are required to enter secure areas of maritime ports. TWIC cards are not required for P/EVOs, but are often useful to those who operate in maritime ports. [ Return to note 78. ]

79 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 2. Available at: [ Return to note 79. ]

80 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 2.5.1 Available at: [ Return to note 80. ]

81 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 2.4. Available at: [ Return to note 81. ]

82 Ibid., Section 2.8. [ Return to note 82. ]

83 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 42. [ Return to note 83. ]

84 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 2.4. Available at: [ Return to note 84. ]

85 Ibid., Section 2.8. [ Return to note 85. ]

86 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 2.8. Available at: [ Return to note 86. ]

87 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 39-40. [ Return to note 87. ]

88 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 3, p. 3-1. Available at: Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 41-42. [ Return to note 88. ]

89 See 49 CFR 393.100 for Federal standards. [ Return to note 89. ]

90 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 3.1, p. 3-1. Available at: [ Return to note 90. ]

91 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 45. [ Return to note 91. ]

92 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 2-40. Available at: [ Return to note 92. ]

93 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 2-40. Available at: [ Return to note 93. ]

94 Federal Motor Carrier Safety Administration, "Hours-of-Service (HOS) Regulations – Comparison," FMCSA-ADO-13-006C (Washington, DC: 2013). Available at: [ Return to note 94. ]

95 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 12. [ Return to note 95. ]

96 Federal Highway Administration, Manual on Uniform Traffic Control Devices, Section 6E-02. See also ANSI, High-Visibility Apparel and Headwear, Section 1A.11 . [ Return to note 96. ]

97 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 12. See also, Manual on Uniform Traffic Control Devices, Section 6E. [ Return to note 97. ]

98 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 13. [ Return to note 98. ]

99 See 49 CFR 393.95 (a). [ Return to note 99. ]

100 40 CFR Part 82, Subpart G. [ Return to note 100. ]

101 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), Section 2.5.2, p. 2-13. Available at: [ Return to note 101. ]

102 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 7 and p. 28. [ Return to note 102. ]

103 Minnesota highlights the FHWA's Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts in its course materials, for example. [ Return to note 130. ]

104 Federal Register, "Regulatory Guidance on the Designation of Steerable Rear Axle Operators (Tillermen) as Drivers of Commercial Motor Vehicles," June 2011. Available at: [ Return to note 104. ]

105 CJ Staff, "Groups ask for clarification on 'tillerman' definition," Commercial Carrier Journal, June 6, 2011. Available at: [ Return to note 105. ]

106 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 37-38. [ Return to note 106. ]

107 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 37-40. [ Return to note 107. ]

108 Federal Highway Administration, "2009 Edition Part 6 Figure 6H-10. Lane Closure on a Two-Lane Road Using Flaggers (TA-10)." Available at: [ Return to note 108. ]

109 Federal Highway Administration, Manual on Uniform Traffic Control Devices, 2009 Edition, "Chapter 6D. Pedestrian and Worker Safety: Section 6D.03 Worker Safety Considerations." Available at: [ Return to note 109. ]

110 Ibid., "Chapter 6C. Temporary Traffic Control Elements: Table 6-C-2. Stopping Sight Distance as a Function of Speed." Available  at: [ Return to note 110. ]

111 Federal Highway Administration, Manual on Uniform Traffic Control Devices, 2009 Edition, "Chapter 6E. Flagger Control: Section 6E.02 High-Visibility Safety Apparel." Available at: [ Return to note 111. ]

112 The only exception is properly marked zones where blasting operations are being conducted. See Pilot Car Information Attachment PC for more information: [ Return to note 112. ]

113 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004), p. 25-26. [ Return to note 113. ]

114 Ibid. [ Return to note 114. ]

115 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014). Available at: [ Return to note 115. ]

116 U.S. Department of Transportation, "Accidents That Shouldn't Happen: A Report of the Grade Crossing Safety Task Force to Secretary Federico Pena," March 1, 1996, pp. 2-3. [ Return to note 116. ]

117 Ibid. [ Return to note 117. ]

118 Ibid., p. 4. [ Return to note 118. ]

119 Ibid., pp. 20-21. [ Return to note 119. ]

120 Federal Motor Carrier Safety Administration, "7 Steps for Safety – Highway Rail Grade Crossings," FMCSA–ESO–06–0014 (Washington, DC: FMCSA, 2010). Available at: [ Return to note 120. ]

121 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 121. ]

122 U.S. Department of Transportation, "Accidents That Shouldn't Happen: A Report of the Grade Crossing Safety Task Force to Secretary Federico Pena," March 1, 1996, p. 28. [ Return to note 122. ]

123 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 123. ]

124 Ibid. [ Return to note 124. ]

125 Federal Motor Carrier Safety Administration, "7 Steps for Safety – Highway Rail Grade Crossings," FMCSA–ESO–06–0014 (Washington, DC: FMCSA, 2010). Available at: [ Return to note 125. ]

126 Ibid. [ Return to note 126. ]

127 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 127. ]

128 Cooper, D. and C. Chapman, Risk Analysis for Large Projects: Models, Methods and Cases (Somerset, NJ: John Wiley & Sons: 1987). [ Return to note 128. ]

129 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 129. ]

130 Ibid., Section 5.4.3, p. 5-8. [ Return to note 130. ]

131 Ibid., Section 2.18.3. [ Return to note 131. ]

132 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 132. ]

133 Ibid., Section 2.17.1. [ Return to note 133. ]

134 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 134. ]

135 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 135. ]

136 Ibid., p. 6-2. [ Return to note 136. ]

137 American Association of Motor Vehicle Administrators, Model Commercial Driver License Manual (AAMVA, July 2014), p. 29. Available at: [ Return to note 137. ]

138 Federal Highway Administration, Pilot Car Escort Training Manual: Best Practices for Pilot Car Escorts (Washington, DC: FHWA, 2004). [ Return to note 138. ]

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