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APPENDIX: CONGESTION MITIGATION MEASURES

This section discusses congestion mitigation measures that can reduce the traffic impacts of PSEs. The first part of this section describes the implications of various event types. Event types are important because they have a large role in determining traffic congestion levels and potential mitigation measures. The second part of the section discusses twelve specific mitigation measures, from traffic control to transit incentives.

Congestion Implications of Various Event Types

The FHWA publication Managing Travel for Planned Special Events Handbook classifies PSEs into five distinct categories. Each of these categories has a distinct impact on the roadway network and on congestion.63 These categories are:

  • Discrete and recurring event at a permanent venue
  • Continuous event
  • Street use event
  • Regional/multi-venue event
  • Rural event

The traffic mitigation measure aspects of each of these event types are discussed in the following paragraphs.

Discrete and Recurring Event at a Permanent Venue

A discrete and recurring event at a permanent venue occurs on a regular basis, and it has a specific starting time and predictable ending time. Events classified under this category have predictable peak arrival and departure rates relative to other categories of planned special events. These events generate high peak-travel demand rates and thus congestion, since people have to arrive by a specific time. Moreover, these events end abruptly upon game completion or perhaps at the conclusion of a final song, which creates high peak departure rates and congestion.

These types of events account for a large share of PSE-caused congestion due to the recurring nature of the high peak demands they create. For example, in Detroit, 75 percent of all PSEs are discrete and recurring events at three permanent venues (the Palace of Auburn Hills, Joe Louis Arena, and Comerica Park). At the same time, however, there are significant opportunities to mitigate congestion, as measures that are adopted at a few key locations can impact a large number of events.

Continuous Event

A continuous event occurs over a single day or multiple days. Unlike a discrete/recurring event at a permanent venue, continuous events do not exhibit sharp peak-arrival and peak-departure rates. Event patrons typically arrive and depart throughout the event day. Aside from conventions and fairs, many continuous events take place at a temporary venue, a park, or other large open space. As a result, roadway and parking capacity issues may arise in the immediate area and increase congestion. Temporary venues may not have a defined spectator capacity, thus creating uncertainties in forecasting event-generated trips, since a "sell-out" cap does not exist. Due to the infrequent nature and relatively low peak demand of these events, there is little opportunity to mitigate congestion.

Street-Use Event

A street-use event occurs on a street requiring temporary closure. These events generally occur in a city or town central business district; however, race events or motorcycle rallies may necessitate temporary closure of arterial streets or limited-access highways, which increases congestion. A street-use event significantly impacts businesses and neighborhoods adjacent to the event site from the perspective of parking and access. A street use event closes a segment(s) of the roadway network and causes background and event traffic to divert onto alternate routes, thus increasing traffic demand on other streets in the roadway network and increasing congestion.

These problems can often be mitigated by scheduling these events at times and locations that will minimize impacts on travelers. Additional focus can be placed on producing adequate information on travel alternatives for both attendees and non-attendees.

Regional/Multi-Venue Event

A regional/multi-venue event refers to multiple planned special events that occur within a region at or near the same time. The collection of events may have different starting times and be of different types. Mitigation of congestion for these events can focus on avoiding scheduling conflicts. For example, in Philadelphia, where multiple sports venues are located in close proximity, the team management groups often meet in order to minimize schedule conflicts.

Rural Event

Rural events encompass any discrete and recurring or continuous event occurring in a rural area. These areas usually have limited road capacity and potentially limited parking capacity, which increases congestion. In addition, the existence of fewer alternate routes to accommodate event and background traffic has an impact on congestion. Rural events also tend to have a lack of regular transit service and hotels near the venue, as well as a lack of permanent infrastructure.

Congestion Mitigation Techniques

The following paragraphs discuss traffic mitigation techniques that can be applied to various transportation modes or infrastructures. Many of these techniques are classified as Intelligent Transportation Systems (ITS). These systems apply information and communications technologies to transportation infrastructure and vehicles in an effort to manage vehicles, loads, and routes to improve safety and reduce vehicle wear, transportation times, and fuel consumption.

Freeway Traffic Control

Some of the key ways to mitigate congestion caused by planned special events on freeways include ramp closures or the addition of capacity. Closing a ramp eliminates merging or weaving maneuvers on that section of freeway. Additional ramp capacity may be added by converting a one-lane ramp to a two-lane ramp during the event by the use of cones. Lane configuration changes can be made to the local street where the ramp intersects to provide two free-flowing lanes onto the local roadway.

Another option in freeway operations is the use of alternate routes. In this manner traffic can be spread over several routes to access a venue. This is especially useful when freeway exits are close together and can provide access to different event parking lots. Motorists attending the planned special event can be informed of alternate exits for a different parking lot that may have more capacity. In this manner, traffic can be split up between different roadways as well as different parking areas.

Ramp metering can also be used to mitigate congestion caused by planned special events. Ramp metering has been used by many agencies to control recurring congestion on freeways during peak periods. The same concepts can be applied to the congestion caused by planned special events.

Rolling roadblocks can be used upstream of a congested ramp junction or weaving area. Rolling roadblocks help to reduce the level of congestion at the primary bottleneck location. Similar to ramp closures, traffic is diverted to another access point, and this helps to eliminate congestion caused by traffic merging with heavy freeway mainline traffic.

Lane diverge prohibitions can be enacted for planned special events using traffic cones. This helps to reduce congestion at diverge ramp junctions caused by motorists attempting to make a sudden lane change to access an exit ramp.

Street Traffic Control

To reduce congestion on the local street system, several tactics can be used, including on-street parking restrictions, vehicle travel on the road shoulder, and alternative lane operations. Alternative lane operations make use of the fact that traffic destined to some planned special events is very directional. In this manner, the lane configurations can be modified to provide more lanes for entering traffic before the planned special event and, conversely, more lanes for exiting traffic after the event. Alternative lane operations can be either reversible lane operations or a contra-flow operation.

A key guidance system for planned special events is a series of trailblazers along the travel route. This helps attendees find the venue and also helps to promote the use of the preferred travel route. When erected along a local flow route, the route marker assemblies collectively trailblaze a route to the drivers' destination of choice.

Intersection Traffic Control

The key to reducing congestion at the intersection level is simplifying traffic movements and minimizing the number of conflict points as well as traffic signal phases. Consideration can be given to prohibiting all left-turn movements. In addition, the number of competing movements can be lowered by a planned road closure.

Traffic Incident Management

Traffic incident management can be used to reduce congestion by adding service patrols during planned special events as well as staging a tow truck on the main access routes. In this manner, any crashes or disabled vehicles can be handled quickly.

En-route Traveler Information

En-route traveler information can be provided to both attendees and non-attendees by way of changeable message signs along the main roadway sections. In addition, highway advisory radio and sources within the media can be utilized, as well as static signing.

Transit Incentives

Transit incentives include transit service expansion by supplementing the existing service with additional vehicle hours. Also, creating a route deviation with a stop near the event venue can increase ridership of the existing service. Transit can also provide an express service to the event site in order to promote its use.

Express bus services also can be used to help reduce congestion. An exclusive bus lane can be provided from park and ride lots to help reduce bus delay as well as promote the service as a less congested way to get to the venue. The best location of these types of facilities will intercept spectator traffic as it approaches the event site.

In order for public transit to be effective, the general public must be made aware of the benefits of using the transit system. This can be accomplished through a comprehensive transit-marketing program that would help to inform the public of the availability of public transit service to/from a special event venue as well as convince them to use the service.

High Occupancy Vehicles

High-occupancy vehicle incentives attempt to increase the number of persons traveling in each vehicle and thus reduce congestion on the roadways. One method to increase high-occupancy vehicle use is to continue HOV restrictions on HOV lanes during planned special events. Another technique is to provide reduced parking fees for vehicles with more than two people at the venue site and/or allow HOV parking in a specially designated lot closer to the entrance of the venue.

Event Patron Incentives

Event patron incentives try to encourage event patrons to arrive early or leave late to reduce congestion on the roadway. Some possible ways to make it attractive for attendees to stay late after an event are post-event fireworks or a concert, special programming on stadium video screens, "Meet the mascot" promotions for children, special discounts with a ticket stub at nearby restaurants, and extended parking at no additional cost for event-goers to encourage their patronage of downtown restaurants and shops after an event.

Some strategies to encourage attendees to arrive early to an event include free drawings and contests that occur before an event, early opening of venue restaurants and the offer of special discounts, encouraging tailgating in venue parking areas, and encouraging spectators to watch teams warm-up before the game.

Venue Operator Roles

To provide successful congestion mitigation for planned special events, the venue operators need to play an active role in the planning of the special event. In order for patrons to arrive early and stay late, the venue operator needs to offer incentives. Venues that do not have pre-event or post-event activities can solicit suggestions from the public through mailings or via the venue website. For example, when season ticket applications or tickets to the event are mailed, an accompanying survey can ask event patrons which type of pre-game or post-game activities they would be more likely to take advantage of. Similar types of questions can be presented on an event or venue website.

As a result, the pre-game or post-game events will cater to the persons who actually attend the event, thus increasing the number of spectators attending staged activities. For recurring events, venue operators can survey the patrons in the venue or distribute suggestion cards when patrons enter or exit. These incentives help to reduce congestion by spreading out the peak arrival and departure rates of event patrons. Collectively, these types of incentives help to make a discrete event more like a continuous event.

Bicycles

Another way to reduce congestion is to encourage the use of bicycles. Accommodations can be made to locate bicycle parking close to the venue entrance. In addition, bicycle racks can be provided on transit buses to allow spectators to access mass transit while carrying a bicycle. Staffed "bicycle valet parking" can allow riders to drop off their bicycles in a secure and supervised temporarily enclosed area during an event, while providing an opportunity for valet staffers to actively promote cycling. This is useful for temporary venues or street closure events where installing many new permanent bicycle racks would not be cost-effective or practical.

Background Traffic

One of the major factors in congestion for any planned special event is the accommodation of background traffic. Drivers who make up this traffic are not attending the event, but they are nonetheless impacted by the presence of the planned special event. One of the major differences between background traffic and attendee traffic is that the travel patterns of the background traffic may be more flexible than those of the event traffic. Thus, it may be possible to adjust the background traffic during times of the planned special event.

Techniques for doing this include increasing the use of public transit through aggressive advertising campaigns, encouraging car pools, and shifting work hours. Some other ways to reduce background traffic include the shift of commercial truck travel routes and delivery schedules. This can be done to avoid travel during times of event ingress and egress and possibly to avoid travel near the event venue all together.

Local business can be encouraged to implement Travel Demand Management techniques by allowing workers to telecommute, encouraging carpooling, and allowing flexible hours, modified delivery schedules, and even early release from work on event dates.

Pre-trip Traveler Information

The purpose of pre-trip traveler information is to assist drivers with decisions regarding route planning, mode of travel, and the time of day to travel. Accurate pre-trip travel information provides benefits to all transportation system users in the form of time and cost savings. Various techniques are used to disseminate information to the public, including both event patrons and non-attendee road users, so they can be better informed when planning their trips to or around a planned special event. The Internet, television and newspapers can all be used as part of an overall pre-trip public information campaign.

Most large events publish an event or venue transportation guide. This can be very helpful in the reduction of congestion on the roadways by providing preferred routes to the venue as well as alerting attendees to any special promotions that may encourage them to come early and/or stay late. Information can also be provided on kiosks in areas near the venue that will have updated information on best routes and local traffic conditions.

Information can also be provided to drivers by the use of changeable message signs and highway advisory radio, as well as static signing. These techniques are especially helpful in informing attendees of the planned special event, as well as non-attendees who drive the route frequently.

Congestion Mitigation Techniques List

The congestion mitigation techniques described above and a few additional techniques are listed in Exhibit A-1.

Exhibit: A-1: List of Congestion Mitigation Techniques Exhibit: A-1: List of Congestion Mitigation Techniques
Strategy Techniques Benefits
Transit Service Strategies
Public transit service expansion

Maximize use of public transit:

  • Existing service with additional vehicle hours
  • Modifying existing service by creating a route with a stop near the event venue
  • Implementation of an express service to establish a special purpose route to and from the event site
Reduces auto traffic and parking demand
Express bus service

Discourage event patrons from driving their vehicles to the event site due to expected site parking deficiencies and anticipated roadway congestion

  • Using express bus service between a park and ride facility or remote parking lot and event venue
  • Using park and ride lots that best intercept spectator traffic as it approaches the event site
Reduces auto traffic and parking demand
Charter service
  • Use a contract service to provide transportation directly to the event site from outlying areas (e.g., other neighborhoods and cities)
  • Consider both charter bus operations and charter rail service
Reduces auto traffic and parking demand
Transit Service marketing

Establish a comprehensive transit marketing program

  • Informing the public of the availability of public transit service to/from the event venue
  • Convincing the public to use the service
Reduces auto traffic and parking demand
Travel Demand Management
High occupancy vehicle (HOV) incentives
  • Consider continuing HOV restrictions on HOV lanes to later weekday hours, or even into weekend hours, in order to encourage event patrons to carpool
  • Reduce weekend parking fees for vehicles with more than two people
  • Provide free advertising for private lots to balance discounts given for HOV parking
Increase the number of persons traveling in each vehicle
Event patron incentives

Consider departure strategies that encourage spectators to stay late after an event:

  • Post-event fireworks or concert
  • Special programming on stadium video screens
  • "Meet the mascot" promotion for children
  • Special discount with a ticket stub at nearby restaurants and pubs
  • Extending parking, at no additional cost, for event-goers to encourage their patronage of downtown restaurants and shops after an event

Consider arrival strategies that encourage spectators to arrive early before an event:

  • Registration in free drawing and contents that occur before an event
  • Early opening of venue restaurants and/or offering of special discounts
  • Tailgating encouraged in venue parking areas
  • Encouraging spectators to watch teams warm-up before the game
Encourage event patrons to arrive earlier or leave late in order to reduce peak traffic demand
Bicyclist accommodation

Provide bicycle and bicyclist friendly services:

  • Provide proper bicycle paths (permanent and temporary)
  • Maximization of safety for bicyclists
  • Avoidance of roadways with higher traffic volumes due to the event
  • Provide security in bicycle parking areas
  • Locate bicycle parking close to venue entrance
  • Provide bicycle racks on transit buses to allow spectators to access mass transit while carrying a bicycle
Encourage the use of bicycles in traveling
Local travel demand management (TDM)

Encourage alternative travel choices:

  • Avoidance of travel during times of event ingress and egress
  • Avoidance of travel near event venue

Encourage businesses to implement TDM strategies:

  • Telecommuting
  • Carpooling
  • Flexible hours
  • Modified delivery schedules
  • Early release from work on event dates for infrequent night events

Use media to announce alternative routes to and around events

Contact commercial trucking companies:

  • Times to avoid routes serving the event venue
  • Reduction of number of truck trips
  • Shifting of some truck trips to nighttime (non-event) hours
Provide road users with more information
Interchange Operation Tactics
Rolling road block Initiate tactic on freeway mainline upstream of congested interchange ramp(s) Alleviates traffic demand at interchange, thus permitting street or ramp bottleneck to dissipate
Rolling road block

Initiate tactic on freeway mainline upstream of a congested ramp junction or weaving area

Use tactic to meter freeway mainline traffic demand without creating a secondary bottleneck upstream of the congested area

Reduces level of congestion at the primary bottleneck location
Entrance ramp closure Initiate tactic on ramps in close proximity to and upstream of interchange target point for event trafficDivert affected traffic to another downstream access point Eliminates congestion caused by traffic merging with heavy freeway mainline traffic
Entrance ramp closure Initiate tactic as necessary to reduce freeway mainline congestion in the vicinity of closely-spaced entrance ramps Reduces freeway mainline congestion or prevents congestion from occurring
Exit ramp closure

Close ramp, as needed, to alleviate congestion on a downstream local flow route

Initiate only if a downstream exit ramp and local street system can handle diverted traffic

Reduces congestion on local flow route
Exit ramp closure Initiate tactic at freeway interchanges connecting local traffic flow routes that have special egress traffic control measures in effect Prevents traffic from accessing local flow routes in the direction of the event venue that operate in favor of egress traffic flow
Elimination of weaving area Close cloverleaf interchange entrance ramp to facilitate unimpeded diverge to access adjacent exit ramp Eliminates weaving area congestion and extends deceleration lane for traffic using exit ramp
Elimination of weaving area Close cloverleaf interchange exit ramp and mainline right-lane to facilitate unimpeded merge with mainline Eliminates weaving area congestion and extends acceleration lane for traffic using entrance ramp
Ramp metering Meter freeway entrance ramps upstream of interchange target point for event traffic Reduces congestion caused by traffic merging with heavy freeway mainline traffic
Ramp metering Meter freeway entrance ramps downstream of interchange target point for event traffic Reduces congestion caused by traffic merging with heavy freeway mainline traffic
Late diverge prohibition Deploy traffic cones along barrier line extending upstream of exit ramp gore area Improves safety and reduces congestion at diverge ramp junction caused by motorists attempting to make a sudden lane-change to access an exit ramp
Additional exit ramp lane Cone an additional lane on exit ramps serving traffic destined to an event venue Provides additional ramp storage capacity and proves particularly effective if two-lane ramp traffic does not have to merge at downstream end of ramp


Effectiveness of PSE Congestion Mitigation Measures

Research on PSE congestion mitigation measures indicates that these measures have the potential to substantially reduce congestion. Two main types of PSE congestion mitigation studies have been identified:

  • Before and after studies that measure traffic conditions before and after specific PSEs.
  • Research studies that use simulation models that incorporate theoretical conditions and/or real-world case studies.

Some state departments of transportation, such as the Michigan Department of Transportation (DOT), regularly conduct before and after event studies, which are also sometimes referred to as after-action reviews.64 An example of the after-action review performed by the Michigan DOT for the 2005 MLB All Star Week is provided in Exhibit A-2.65 As Exhibit A-2 shows, the observations made in after-action reviews can be qualitative.

Exhibit A-2: After-Action Review for the 2005 MLB All Star Week
Topic Notes
Ingress Traffic
  • I-94 was slow around the I-96 interchange because of construction activity.
    • The secondary route included use of the NB M-39 to EB I-96 ramp, which was closed on the days-of-event. It was thought that this ramp would be open.
Egress Traffic
  • Woodward traffic flowed very well once past (west/north of) the I-75 Service Drive.
    • Officers did not override the signal timing plan (e.g., implementation of "double-green").
  • Temple was backed up due to parking on both sides.
  • Southbound Woodward was congested near Jefferson due to parking.
Day-of-Event
  • Traffic was a "non-event" and spectators were orderly.
  • Michigan State Police reported that freeway operations went extremely well.


As mentioned earlier, there are also research studies that use simulation models that incorporate theoretical conditions and/or real world case studies. In recent years, many state and local authorizes have required that PSE traffic impact research studies be conducted prior to the construction of new large event-hosting facilities. Other research reports have examined the traffic mitigation impacts of introducing ITS at existing venues. Two important reports on this topic were prepared by the University of California Transportation Center and the Maricopa County Department of Transportation.

The University of California Transportation Center report, Simulation of Advanced Traveler Information Systems (ATIS) Strategies to Reduce Non-Recurring Congestion from Special Events,66 uses the DYNASMART simulation to estimate delays corresponding to an event venue with three different attendance levels: 5,000, 10,000, and 15,000 vehicles. Travel time reductions associated with the introduction of ITS systems ranged from 14 to 34 percent for attendees and from 10 to 13 percent for non-attendees.

The Maricopa County Department of Transportation report examines the introduction of ITS to the Phoenix International Raceway in Maricopa County, Arizona. The report estimates that travel time for outbound travel from the events decreased from 5.5 hours in 1998 to 2.5 hours in 2005 as a result of capacity enhancements and application of ITS. The ITS measures that were introduced to the Phoenix International Raceway area included cameras, Dynamic Message Signs (DMS), and Traffic Management Centers (TMC).67




63 S. Latoski, W. Dunn, Jr., B. Wagenblast, J. Randall, M. Walker. M., "Managing Travel for Planned Special Events," FHWA Report #OP-04-010 (U.S. Department of Transportation, September 2003).

64 "After Action Report, 2005 North American International Auto Show and Winter Blast," Dunn Engineering Associates, February 15, 2005.

65 "After Action Report, 2004 Thanksgiving Day Special Events," Dunn Engineering Associates, January 19, 2005.

66R. Jayakrishnan, M. McNally, M. Cohen, "Simulation of Advanced Traveler Information Systems (ATIS) Strategies to Reduce Non-Recurring Congestion from Special Events," University of California Transportation Center, UCTC No. 173 (August 1993).

67N. Swart, "Phoenix International Raceway (PIR) Traffic Management," Maricopa County DOT, April 26, 2005.

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