Roles of Transportation Management Centers in Incident Management on Managed Lanes
Chapter 4-TMC Role in the Managed Lane Environment-Real Time TIM Response Activities and Support
Traffic Incident Management (TIM) is one of the primary functions of a TMC. TMCs are equipped with a wide variety of systems that support the real time monitoring of the highway, detect incidents, coordinate/support response, and distribute traveler information.
TMCs are usually operational at all times, or at least during hours that cover the most congested time periods. TMCs have operations personnel resources and the expertise to perform TIM functions.
The most effective use of the TMC's resources is critical to ensure prompt detection, response, and clearance of an incident in the managed lanes. The focus of this chapter will be on TMC practices learned through the literature investigation that will minimize detection and response time, provide adequate travel information to users of the managed lanes, and effectively control vehicular access to the incident scene to allow for quick clearance of the incident and return to normal operations.
Figure 28. Photo. Traffic incident and response.
TIM is formally defined by FHWA as, "the process of coordinating the resources of a number of different partner agencies and private sector companies to detect, respond to, and clear traffic incidents as quickly as possible to reduce the impacts of incidents on safety and congestion, while protecting the safety of on-scene responders and the traveling public." In a managed lane environment where the managed lane is operated by a different entity than the general purpose lanes, this coordination is particularly important, especially in situations where there are multiple TMCs responsible for operation of the corridor. Strong partnerships and previously agreed upon operating procedures should be developed among transportation and response agencies to ensure smooth operation of the managed lane facility. Priced managed lanes in particular require significant real-time traffic management, including monitoring traffic and responding to incidents.
Figure 29. Photo. The I-495 Express Lanes in Fairfax County, VA are privately operated while the general purpose lanes are operated by the state DOT, yet they must function as a unified transportation system.
TMCs often treat the transportation network as a single system and have extensive experience in coordinating operations with multiple operating partners. During different types of incidents, the specific details of sharing responsibilities will be critical to ensure that the incident is detected, verified, responded to, and resolved efficiently. TIM on a managed lane and especially a priced managed lane is important to maintain the reliable and quick trip that motorists expect from the facility. A variety of entities may be involved in this function including state DOTs, state highway patrol, local emergency response units, and private towing and recovery contractors. The degree of coordination challenges increase if the agencies are not co-located in a single TMC, or if one of the operators is a private sector entity. In these cases to coordinate TIM efforts between key stakeholders responsible for the corridor, formal interagency agreements and joint operations protocols should be implemented. These protocols should aim for quick response and incident clearance, and outline the individual responsibilities of each entity.
The following situations would require additional coordination among the different entities involved in operating a managed lane facility:
In the event of an incident on the general purpose lanes, responders might need to use the managed lanes to respond to the incident. If an incident occurs on the managed lane or the general purpose lane, traffic might need to be diverted to the adjacent lanes. If different agencies operate the general purpose and managed lanes, revenue considerations may complicate agency speed or desire to implement diversions, but sometimes it is absolutely necessary. For example the I-15 HOT Lanes in San Diego, CA have procedures in place where tolls can be remotely eliminated if an incident occurs within the express lanes. If an incident occurs on the general purpose lanes, CalTrans has the ability to open the express lanes to all traffic. Similarly, tolls are not collected when the express lanes are used by general traffic.
Where there are multiple TMCs responsible for operation of a corridor, personnel at both TMCs must work together to ensure that the corridor functions seamlessly as a single transportation system. If one TMC is responsible for the managed lanes and another TMC covers the general purpose lanes, each TMC should have procedures in place to establish quick communication with the other TMC in the event of an incident, as it is possible that an incident can be detected by the "wrong" TMC. The correct TMC can then take the lead on the incident response.
In some cases, the managed lane operator may not have a fully equipped TMC, and may instead rely upon a regional TMC for assistance with TIM. In such cases, it is critical to have agreements in place covering various incident types and severities such that the TMC is ready to support the managed lane operator when an incident occurs. The TMC may not have direct operational control over the managed lanes, but it can still provide assistance with dissemination of traveler information, dispatching responder resources, and assisting with scene management.
Specific examples of shared operations responsibility include:
I-10 Katy Freeway (Houston, TX)
I-495 Express Lanes (Fairfax County, VA)
I-85 Express Lanes (Atlanta, GA)
I-15 Express Lanes (San Diego, CA)
Ideally, interagency agreements regarding TIM policies that include information sharing and incident response procedures should be in place and familiar to all entities involved in the operation of the managed lanes, such that all stakeholders are on the same page regarding which agency is responsible for what when an incident occurs.
The stages of the typical TIM process involve the following as depicted in Figure 28:
The TIM process for incidents in managed lanes is the same as for incidents occurring in general purpose lanes and other areas. The process has been implemented and tweaked over many years; however each managed lane system has its own unique considerations due to each unique operating environment and these must be addressed in any customized TIM plan.
Figure 30. Chart. Stages of the TIM process.
Detection and verification are the initial stages of TIM where vital information is gathered on an incident. Detection involves determining that an incident has occurred and notifying the agency or agencies that are responsible for maintaining the roadway. Detection methods can be grouped into the following three general categories: Public Input, ITS Components, and Responder Reports. Examples for each method include:
Figure 31. Photo. Verification of the exact location of the incident is important when there is physical separation between lanes.
In urban areas where managed lanes are present, there are higher traffic volumes and robust cell phone coverage, which will lead to quicker detection of incidents. Ability to detect an incident faster helps to begin the TIM process to clear the incident as soon as possible.
After detection, verification is the key next step during TIM. Verification involves confirming that an incident has actually occurred, including determining the type of incident, determining its exact location, and gathering as much pertinent information needed to dispatch the proper response personnel and resources. Proper verification of an incident in a managed lane environment is very important, especially where there is physical separation between the managed lanes and general purpose lanes. An improper verification could lead to incident response being dispatched to the wrong side of the physical separation, which will lead to longer clearance times since resources must be repositioned. Verification can be performed onsite by emergency personnel or offsite by TMC personnel and generally include the following methods:
Since managed lanes may involve multiple agencies it is especially important that TMCs have the capability to gather information from different sources. The collective information received from these sources should be used by the TMC to ascertain the type and severity of an incident, identify which agency has primary jurisdiction, and relay this information to the appropriate responding agencies.
Effective incident detection and verification is especially important for managed lanes because:
Incident response is typically considered the most important component of the TIM process. Incident response involves dispatching the appropriate personnel/equipment and activating the appropriate communication links and motorist information to media that a traffic incident has occurred. In order to facilitate a timely and effective response it is important that TMCs coordinate with enforcement personnel and other incident responders on the dispatch of response to collect all necessary information. The following are a few sample questions that TMC staff should ask when corresponding with emergency personnel or other persons reporting an incident:
Disseminating the incident details collected is a significant role for the TMC because dispatching incorrect equipment and resources can have adverse effects on managing an incident, which can result in increased clearance times, or secondary incidents, or possibly even further injuries and fatalities. TMCs often have access to dedicated safety service patrols that are able to respond quickly and provide assistance at an incident scene.
Some agencies utilize "simultaneous dispatch", whereby law enforcement and service patrol vehicles are dispatched while the verification step is occurring. After the information is verified, any updated information can be communicated to the responders via radio, CAD, or response agency dispatchers.
Figure 32. Photo. These New York State DOT HELP trucks have onboard cameras linked to the TMC to provide realtime incident information.
Figure 33. Photo. Pre-positioned service vehicles or service vehicles on a roving patrol can monitor the managed lanes and provide quick response if an incident occurs.
The managed lane environment may present additional challenges to traditional incident response functions coordinated by a TMC, as there may be limited physical access to the managed lanes for responders, and the lanes may have reduced or restricted space for TIM zones, which can complicate TIM response and the ability to establish a safe TIM zone. To overcome this challenge it may be beneficial to have prepositioned response and recovery vehicles at key locations along the managed lane, especially where recovery vehicles may have limited ability to enter a managed lane facility. As mentioned previously, TMCs coordinate with dedicated safety service patrols so it would be ideal to have these patrols monitor the managed lanes to quickly aid in a response when an incident occurs. For example, in the Hudson Valley region of New York there are dedicated Highway Emergency Local Patrol (HELP) vehicles that patrol designated routes and are equipped with a live video stream to the TMC. The dashboard cameras are used to automatically relay real time incident information to TMC personnel which allows them to visually see incident details that aid in expediting a response.
Another method used to coordinate response efforts is the development of TIM teams along the managed lanes dedicated to responding to incidents. The mission of TIM teams is an inter-agency coordination among all emergency responders to understand the need for quickly and safely responding and clearing incidents from the highway. TIM needs vary from state to state, so TIM teams have the ability to adjust to the needs of their jurisdiction. Urban areas that generally have a large amount of congestion and incidents may require a response from multiple agencies, whereas non-urban areas may require a response from only one or two agencies. Additionally a managed lane environment might fall under the jurisdiction of multiple agencies, so it is important to develop these TIM teams in advance to communicate regularly and coordinate response efforts.
The US Fire Administration's Traffic Incident Management Systems Report (FA-330, March, 2012) includes an extensive discussion of traffic incident management responder safety, scene management and traffic control.
Providing a timely and effective response reduces incident durations and ultimately the amount of time the roadway operates at a reduced capacity. This is especially important for priced managed lane systems where reduced capacity could affect the amount of revenue collected.
TMCs can be used effectively to support incident site management and traffic control in managed lanes, in many cases using unique assets that may be available in those lanes. TMCs support quick, safe and efficient response to the incident by coordinating with on scene response personnel to set up a safe traffic control strategy and safe incident scene. TMCs can use a variety of transportation management strategies to control the traffic that will use the facility to meet the objective of safe incident clearance. This reduces congestion, helps to create a safer incident management zone, and hastens incident clearance.
Figure 34. Photo. Incident scene management using DMS messages.
The following describes these strategies and actions in more detail.
Scene management involves the establishment of a safe and effective area where responders can deal with the incident response and clearance. Ideally, if vehicles are drivable and there are no injuries, the vehicles can be moved to a shoulder, pull off area, or off the roadway. If the vehicles cannot be moved, then traffic can be routed around in the vicinity of the scene or, if necessary, diverted from the area. Managed lanes can introduce complexities with scene management when the shoulder area is limited and cannot accommodate the incident scene set up without impacting traffic flow, or where barriers may make it difficult or impossible to allow vehicles to exit or to divert traffic in the immediate vicinity of the scene. Scene management also involves elements such as proper parking of response vehicles and the use of high visibility apparel. Accordingly, it is primarily the function of the onsite responders. However, the TMC can support effective scene management in the followings ways:
Figure 35. Illustration. Incident zone traffic control to create a safe work area.
Implementing effective traffic control at and around the incident management scene can help increase the safety of the responders as well as reduce the potential for secondary vehicle incidents. It may involve either providing for the safe passage of vehicles around the scene or diverting traffic away from the scene entirely.
The TMC can support effective traffic control for the incident in the following ways:
Additional actions such as controlling vehicle access to the facility to reduce traffic volumes via revised managed lane pricing or eligibility or through access control at the access and egress to the managed lanes are discussed in the subsection on Vehicle Access Management. The ability for a TMC to implement pricing or eligibility changes may be limited by state and local laws.
The following are examples of effective TIM-related scene management and traffic control strategies for managed lanes:
I-15 Express Lanes (San Diego, CA)
I-85 Express Lanes (Atlanta, GA)
I-93 Contraflow HOV Lane (Boston, MA)
Figure 36. Photo. Some managed lanes can adjust vehicle occupancy thresholds or suspend access by tolled vehicles.
Vehicle Access Management
One of the unique aspects of some types of managed lanes is that the TMC may have the ability to alter vehicle access to the managed lanes in order to reduce congestion, create a safer incident management zone, and hasten incident clearance. This can be done by changing vehicle eligibility (raise occupancy requirements or eliminate access for toll paying vehicles into HOT lanes), pricing (raise the vehicle use price), or through access control (utilizing gates or signals). Many of these access changes can be made directly from the TMC. In some cases the TMC may have to use its communication infrastructure to coordinate with ground personnel to implement the changes and monitor the effects. This section discusses these unique access management techniques and how they can enhance TIM in managed lanes.
It should be noted that the vehicle access management techniques described below are usually accomplished through information and control systems. These systems are implemented by the TMC responsible for operations of the managed lane. In cases where separate TMCs control the managed lanes and general purpose lanes, coordination between the two TMCs is required. In cases where a separate toll agency is involved, coordination with that agency may be required if revenues will be affected. In these cases it is important to work out system functional and control issues and create operational agreements and protocols during the system design phase.
The most common eligibility requirement associated with managed lanes is vehicle occupancy. Typically, HOT lanes allow free use of the managed lane based on a minimum number of vehicle occupants - usually two or three. In the event of an incident requiring reducing the traffic volumes in the managed lanes, it might be possible to temporarily raise an HOV 2 requirement to HOV 3 if local laws and policies allow this strategy. The TMC could implement this change using tools such as DMS and managed lane access signs at the points of entry. However, HOV occupancy enforcement requires manual techniques and it may be difficult to get full compliance. An alternative vehicle eligibility change could be to suspend access by single-occupant vehicles in a HOT lane and only allow HOVs. This can be implemented without adjusting the occupancy threshold, which may not be allowed based on the state's laws. The managed lane could also be closed completely if necessary. Techniques for such situations are described in the below section Access Control.
Many managed lanes have a pricing element to them, such as HOT lanes and ETLs. Pricing allows vehicles not meeting eligibility requirements (such as HOV 2) to use the lane by paying a toll. The toll is usually variable, based upon factors such as time of day or congestion levels. Vehicles using the lane via pricing eligibility usually need to have a toll tag. Pricing technology allows the operating agency to meter traffic to optimize travel on the managed lane and also allows for a TMC to meter traffic flow in response to an incident. The price can be raised to very high levels to greatly reduce the toll-paying traffic. Priced managed lanes are equipped with systems for altering the toll charge, via DMS or signs at the managed lane access point of entry. There may also be separate lanes for toll paying vehicles and those can be closed as described in the below section Access Control.
Figure 37. Photo. Priced managed lanes can increase the toll price to reduce demand.
There are a variety of ways in which physical access to managed lanes may be controlled. In all cases, TMCs would play a primary role either in direct operations or coordination of operations. Access control techniques that are largely technology-based include:
Figure 38. Photo. Some managed lanes have signs and gates that can be used to quickly close the lanes during an incident.
In some cases, the design of the managed lane does not facilitate the use of technology-based access control systems. In these situations it is necessary to implement techniques that are more manual oriented such as:
In any case, whether access control is technology-based or manual-based, it can be seen that the TMC will play a large role in adjusting access control to facilitate TIM in managed lanes.
The following are examples of effective TIM-related access management systems for managed lanes:
I-15 Express Lanes (San Diego, CA)
I-35W (Twin Cities Metropolitan Area, MN)
Clearance and recovery comprise the final stages of the typical TIM process. Clearance involves removing wreckage, debris, or any other elements of a traffic incident that disrupt the normal flow of traffic. The impacts of an incident can extend beyond the managed lanes to the general purpose lanes and other parallel roadways in the regional transportation network. Therefore, improving clearance procedures could have positive effects including: minimizing motorist delay, enhancing the safety of responders and travelers, and minimizing the loss of revenue.
Figure 39. Photo. Effective clearance may be challenging in managed lanes with no shoulders and physical barriers, such as this zipper lane in New York City.
Recovery involves evaluating what the long-term impacts of an incident may be and identifying what recovery actions might be needed to mitigate those impacts. The ultimate goal of recovery is to restore the roadway capacity to its previous condition before the incident occurred, and to have the managed lane fully operating, collecting tolls if applicable, and providing premium service to eligible users. Recovery actions include:
TMCs provide unparalleled support to the quick clearance and recovery of traffic incidents by coordinating with responders to support any needs for additional resources such as tow trucks, medical support, environmental response, or other assistance.
In a managed lane environment several factors may provide challenges to quick incident clearance, such as accessibility of the incident scene and coordination among various responding agencies. To facilitate the clearance of an incident, managed lane operators may use managed lanes to divert traffic, and lane control signs to indicate which lanes are open and closed. After clearing the incident, normal operation of the managed lane facility resumes and signage returns to normal.
Effective clearance and recovery protocols are critically important to the success of priced managed lanes because the longer an incident is on the roadway the less revenue is collected. If priced managed lanes are not providing an enhanced traveling experience, then motorists will not see its advantage and not be motivated to use them.
Previous sections in this chapter discussed TMC activities related to the typical TIM process. Those sections were primarily directed at actions that will occur at or near the scene or on the affected facility. Although system and corridor management is not part of the typical TIM process, it is a real-time response activity that can be implemented depending upon the functionality of the TMC.
A significant incident on a major limited access facility containing a managed lane will quickly affect and be affected by traffic conditions. TMCs have a variety of transportation management strategies and tools that can be used at a system and corridor level to reduce the traffic that will use a managed lane facility during an incident and encourage travel around the incident.
The current USDOT Integrated Corridor Management (ICM) Program is directed at integrating travel in corridors and provides a forward looking example of the wide variety of transportation management options that can be implemented for this purpose. While most TMC sites in the United States do not have all the capabilities to fully implement TIM from an ICM perspective at this time, most sites have many of the tools.
The strategies include:
Lane Control Signals
Use devices such as lane control signals and signs to implement or warn of lane closures, or reduced speed limits, or to close lanes well in advance of the scene.
Figure 40. Photo. Use of lane control signals to close lanes on the I-35W PDSL in Minneapolis.
Modify ramp metering signal timing to reduce traffic volumes entering the facility.
TMCs can use systems such as 511, DMS and Highway Advisory Radio (HAR) across the corridor to alert travelers of the incident and the best way to avoid the related congestion.
Arterial Traffic Signal Timing Adjustment
TMCs can adjust signal timing on adjacent frontage roads, arterials and local streets to accommodate increased traffic on these facilities as traffic diverts.
Park and Ride Status and Modal Transfer
In some areas, TMCs have access to the unused capacity of nearby Park and Ride lots and can post DMS messages advising travelers they can change travel modes if parking is available.
Where formal traffic diversions are implemented, TMCs can use DMS and other travel information devices to advise of the diversion and trail blaze motorists through the diversion route.
Where detection information is available, TMCs can use DMS and other travel information devices to advise travelers of comparative travel time route alternatives. This allows travelers to make their own assessment of any need to change route, mode or time of travel.
Figure 41. Photo. Signs displaying travel times via private vehicle and public transit can encourage modal shift during incidents.
Expanded Motorist Assist Patrols
As congestion extends further from the affected managed lane facility, TMCs can adjust the times and roadways of coverage of their motorist assist patrols to focus them on the area most affected and help keep those facilities moving at optimum efficiency.
In the context of the corridor-level strategies, a single TMC will rarely have the capability to implement all the strategies across an entire corridor. The TMC will need to coordinate with numerous adjacent TMCs and agencies to accomplish a true corridor effect, which is consistent with the concept of ICM.
The following are examples of effective TIM-related corridor management strategies for managed lanes:
I-35W (Twin Cities Metropolitan Area, MN)
I-495 HOV Lanes (Long Island, NY)
The TMC controls the traffic signals on the I-495 frontage roads and can adjust signal timing in the event of a major incident.
This checklist can be used by TMCs and/or operators of managed lanes to identify the real-time response activities and support actions that TMCs can take to support TIM in managed lanes. It will help in the understanding of which unique aspects of TIM response and support are applicable, or are potentially applicable, to their managed lane facility. This checklist could be used by operators of managed lanes to identify gaps in their TIM response or support functionalities that could lead to improvements in operation if addressed.
Determine entities involved.
Contact information and point-of-contacts of each entity.
Incident Detection and Verification
Detect and confirm incident.
Gather incident details from public input, ITS components, and responder reports.
Dispatch the appropriate personnel/equipment.
Activate the appropriate communication links.
Management of Vehicle Access During Incidents in Managed Lanes
Manage vehicle eligibility.
Manage access control.
Clearance and Recovery
Coordinate with responders to support any needs for additional resources.
Scene Management and Control During Incidents in Managed Lanes
Scene Management Activities.
Provide traveler information.
Determine site selection and monitoring.
Communication with responders and follow the evolution of response plan and actions.
Dispatch support such as motorist assist patrols for scene management and clearance.
Coordinate, if necessary, with agencies responsible for opening access to support responder ingress and egress.
Traffic Control Activities.
Coordinate with responders to develop traffic control plan.
Support traffic control plan implementation via dispatch of support resources such as traffic response teams.
Coordinate, if necessary, with agencies responsible to open access to the managed lane for traffic diversion.
If present, adjust or coordinate the adjustment of movable barriers to support needed traffic flow.
Where available, open the use of special use lanes such as HOV or shoulder lanes to improve traffic flow around the scene.
Implement System and Corridor Management Strategies and Systems
Lane control signals.
Arterial signal timing.
Park and Ride status.
Display travel time information on DMS.
Expand/relocate motorist assist patrol services.
United States Department of Transportation - Federal Highway Administration