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In September 2004, the Federal Highway Administration (FHWA) published updates to rules that govern work zone safety and mobility.1 Under the new rule, all highway construction and maintenance projects that use federal-aid highway funds are required to develop transportation management plans (TMP) that not only ensure the safety of the motoring public, but also reduce the traffic mobility impacts and promote coordination within and around work zones. A TMP is a collection of administrative, procedural, and operational strategies for managing and mitigating the impacts of work zones. Traffic incident management (TIM) is one of the tools available for transportation professionals to relieve the impacts of work zones on traffic operations.

Before beginning the process of developing a TIM program for work zones, it is important for work zone planners, operations personnel, and incident responders to understand what a TMP is and why it is important in the process of developing TIM programs.

What is a Transportation Management Plan?

A TMP lays out a set of coordinated transportation management strategies and describes how they will be used to manage the work zone impacts of a road project.2 Developing a TMP is an iterative process that involves the identification and evaluation of applicable transportation management strategies to manage the impacts of the construction project on traffic operations. These strategies include not only the deployment of temporary traffic control measures and devices, but also public information and outreach, and operational strategies, such as travel demand management, signal retiming, and traffic incident management.

What are the Components of a Transportation Management Plan?

As shown in Figure 1, a TMP consists of three functional components:2 a Temporary Traffic Control (TTC) plan, a Transportation Operations (TO) plan, and a Public Information (PI) plan; depending upon the expected impacts of the work zone on transportation operations.

The TTC plan describes the measures that will be used to facilitate road users through the work zone and is required for all construction and maintenance projects. The TTC plan must be consistent with Part 6 of the Manual on Uniform Traffic Control Devices (MUTCD)3 and with the hardware requirements of Chapter 9, “Traffic Barriers, Traffic Control Devices and Other Safety Features for Work Zones,” of the American Association of State and Highway Officials’ (AASHTO) Roadside Design Guide.4 The TO plan component identifies the strategies that will be used to mitigate the impacts of the work on the operation and management of the transportation system within the work zone impact area. The PI plan component describes the strategies that will be used to communicate and inform affected road users, the general public, area residences and businesses, and others about the potential impacts of the work zone and changing project conditions. TO and PI elements are required for all projects deemed to have a significant impact on traffic and encouraged for all construction and maintenance projects.

The nature, scope, and level of detail contained in these components depends upon the nature, scope, duration, extent of the work zone activities and levels of safety and mobility impacts of the work zone.

Figure 1. Components of a Transportation Management Plan

TMP consists of strategies to manage impacts of work zones.

Why is a Transportation Management Plan Needed?

Some of the key benefits that agencies can expect to be derived from developing TMPs for work zones include the following:2

  • Increased awareness of the broader safety and mobility impacts that work zones have at the corridor and network levels;
  • More efficient and effective utilization of construction phasing and staging, which in turn can reduce contract duration and control costs;
  • Improved work zone safety for both construction personnel and the traveling public;
  • Reduction in the impacts of work zones on traffic operations and mobility;
  • Reduction in the number of complaints from the travelling public, local businesses, and communities on the effects of work zone congestion;
  • Reduction in circulation, access, and mobility impacts to local communities and businesses;
  • Improved intra- and inter-agency cooperation and coordination; and
  • Clearer understanding of the roles, responsibilities, and actions to be performed to reduce the impacts of work zone traffic operations.

When is a Transportation Management Plan Needed?

As outlined in Rule 630, every project that utilizes federal-aid highway funds is required to have a TMP. At a minimum, every TMP must contain at least a TTC plan. Whether a TMP needs to have a TO or PI component depends on whether or not a project is expected to be “significant.” Rule 630 defines a “significant” project as “one that, alone or in combination with other concurrent projects nearby is anticipated to cause sustained work zone impacts…that are greater than what is considered tolerable based on State policy and/or engineering judgment.” While every project may not require TO and PI components, states are encouraged to consider TO and PI components for all projects.

Factors that should be considered in developing the contents of a TMP include the following:2

  • Type of construction project (e.g., new construction, major reconstruction, major rehabilitation, or bridge/pavement replacement)
  • Degree of roadway congestion at and/or near the project location
  • Type, number, and duration of capacity restrictions (e.g., lane, ramp, or facility closures)
  • Impact on mobility through and within the project area
  • Impact of safety through and within the project/work zone impact area
  • Impact on local businesses and communities
  • Impact from or on special events and/or seasonal variations (e.g., weather, tourist traffic, etc.)
  • Presence of major traffic generators or special traffic generators (such as freight warehouses or distribution centers) in the vicinity of the project
  • Availability of suitable detour or alternative routes or other transportation options (such as transit) in the corridor
  • Traffic characteristics, such as local versus through traffic, percent trucks, etc.

Who Needs to be Involved in the Development of a Transportation Management Plan?

Rule 630 states that the TMP shall be included as part of the construction documentation ­– the Plans, Specifications, and Estimates (PS&Es)  – prepared for a project. Rule 630 also permits state agencies to allow the contractor to develop a TMP; and states that if a contractor is used to develop a TMP, it is subject to approval by the state and shall not be implemented in the field before it is approved by the state. PS&Es shall include appropriate pay item provisions for implementing the TMP, either through method- or performance-based specifications.

TMPs should not be developed in isolation, but should be developed in “sustained consultation” with other stakeholders that are likely to be impacted by the construction activities. The stakeholders for any particular project depend on the extent, duration, and impact of the construction activities on traffic operations in the surrounding transportation network. Potential stakeholders that should be consulted in the development of a TMP might include one or more of the following entities:2

  • Other state and local transportation agencies, including regional mobility authorities and toll road operators,
  • Railroad agencies/operators,
  • Transit providers,
  • Freight movers,
  • Public and private utility suppliers,
  • State and local police agencies,
  • Fire and emergency medical service providers,
  • Schools,
  • Business communities,
  • Neighborhood associations, and
  • Regional transportation management centers.

What is the Process for Developing a Transportation Management Plan?

FHWA’s Developing and Implementing Transportation Management Plans for Work Zones2 outlines an 11-step process that agencies can follow to develop a TMP. The steps in the process include the following:

  • Step 1. Compile project material for each stage of the project.
  • Step 2. Determine the type of TMP needed for specific projects.
  • Step 3. Identify appropriate stakeholders.
  • Step 4. Develop initial TMP.
  • Step 5. Update and revise initial TMP.
  • Step 6. Finalize construction phasing/staging and TMP.
  • Step 7. Re-evaluate and revise TMP.
  • Step 8. Implement TMP.
  • Step 9. Monitor the performance of the TMP.
  • Step 10. Update/Revise TMP based on performance metrics.
  • Step 11. Conduct post-project TMP evaluation.

For more details on the process for developing transportation management plans, see FHWA’s Work Zone Mobility and Safety Program Web site.

What do Transportation Management Plans Have to do With Traffic Incident Management?

One strategy for reducing work zone impacts involves monitoring traffic conditions and making real-time adjustments to traffic operations based on these observed changes. Traffic incidents are events that disrupt the normal flow of traffic, usually by physical impedance in the travel lanes. These events can be vehicular crashes, breakdowns, or debris in travel lanes. Incident management involves deploying technology, establishing procedures and policies, and implementing systems for improving the detection, verification, response, and clearance of these events when they occur in the work zone and on associated detour routes. Therefore, one element of the TO component of the TMP is to establish a TIM program that provides specialized techniques for detecting, verifying, responding to, and clearing incidents in work zones.

Factors Impacting the Need for Work Zone Incident Management

Not every work zone requires that special incident management procedures and practices be put into place prior to construction beginning. A work zone that is associated with a short-term maintenance activity located on a low-volume, rural roadway may only require that maintenance personnel meet with incident responders to discuss detection and clearance procedures. Long-term construction projects, which require extensive lane closures for extended periods, are likely to have a more severe impact on traffic operation and, thus, require a more comprehensive set of incident management policies and procedures to minimize the impact of incidents within the work zone. The effects of incidents on traffic operations in a work zone are influenced by two key factors: the intensity of the work zone and the intensity of the incident.

Intensity of the Work Zone

Work zone intensity is defined by three parameters: the duration of the work zone project, the length of the work zone, and the number of travel lanes that are affected by the work zone5. A work zone project that reduces the number of travel lanes for an extended period throughout the day over an extended length of roadway has a greater impact on traffic operations than one that uses fewer lanes over a shorter distance for less time. Other factors that influence the impacts of work zones on traffic operations include the:

  • Functional classification of the roadway on which the work zone is located,
  • Type of work activity being performed in the work zone area,
  • Type of area where the work zone is located (i.e., rural, suburban, or urban area),
  • Type and amount of traffic using the facility,
  • Proximity of the work zone to special trip generators, such a large commercial or office complexes, schools, special event facilities, etc. and
  • The availability of alternate modes and routes in the corridor.

Work zone planners should work with traffic operations personnel and incident responders to assess the impact a proposed construction or maintenance activity may have on traffic operations and incident management activities. Some agencies have developed relatively simple criteria for determining the impact of a work zone on traffic operations. Other agencies, however, may require more extensive data collection and analysis procedures. Procedures for assessing the impact of work zones on traffic operations can be found in Work Zone Impact Assessment: An Approach to Assess and Manage Work Zone Safety and Mobility Impacts of Road Projects.6

Intensity of the Incident

In addition to intensity of the work zone, the intensity of the incident also affects the degree to which an incident will impact traffic operations on a roadway. Three factors can generally be used to characterize the intensity of an incident: the amount of capacity reduction (i.e., the number of lanes) impacted by the incident, the amount of time that the capacity reduction is in effect, and the amount of traffic demand entering the incident area at the time of the incident. Each of these factors is discussed below.

Amount of Capacity Reduction

The amount of capacity reduction caused by an incident depends on the proportion of the travel lane that is blocked by the stopped vehicle and the total number of available lanes on the roadway before the incident occurred. The Highway Capacity Manual8 shows that when an incident occurs on a freeway the amount of capacity loss is greater than the proportion of original capacity that is physically blocked. For example, when an incident blocks only one lane of a three-lane facility, the freeway retains only 49 percent of its original traffic moving capacity even though the physical capacity of the roadway is reduced by 33 percent.

Because of factors such as narrowed lanes, lack of shoulders, limited access, decreased or shifted travel lanes, speed reduction, and the presence of obstructions, barriers, and equipment being located closer than expected, work zones already have reduced capacity levels. That is why incidents that occur in work zones tend to have a greater impact on traffic operations than if the same incident occurred when the work zone was not present. Therefore, one method of reducing the impact of incidents in work zones is to employ strategies that temporarily restore the roadway capacity. Examples of strategies that temporarily enhance capacity in work zones include:

  • Temporary use of the shoulder as a travel lane,
  • Reopen lanes originally closed or blocked for work zone purposes, and
  • Shift traffic to alternate routes where excess capacity exists.
Incident Duration

The amount of time that a lane is blocked or affected by an incident is another major factor that contributes to the amount of congestion caused by an incident. The longer the incident reduces the roadway capacity, the greater the amount of time it will take for the congestion to dissipate. Therefore, many incident management procedures and strategies are directed toward reducing the duration that an incident blocks the roadway. As work zones already have reduced capacities, reducing the duration of an incident can significantly reduce the impact of an incident on traffic operations in the work zone. Strategies commonly used to reduce the duration of incidents in work zones include:

  • Installing technology and processes to shorten the time required to detect and verify incidents
  • Using procedures and practices for shortening the amount of time required to respond to incidents, and
  • Implementing policies and procedures that shorten the amount of time required to remove (or clear) the incident from the travel lanes.
Traffic Demands

A final way in which incidents affect traffic operation is in the time of day and the amount of traffic using the roadway (i.e., traffic demand) when the incident occurs. Incidents that occur during peak condition generally have a greater impact on traffic operations than if the same incident occurred on the roadway late at night when demand for the roadway was not as great. This is the same reason why work zone planners frequently prohibit lane closures during peak periods and, instead, require the work activity to occur when traffic demands are lighter (for example during off-peak periods or at night).

One method of reducing the effects of incidents in work zones is to reduce the amount of traffic using the roadway at the time of the incident. Because incidents are random events and cannot be predicted, the only way to reduce demand is to warn motorists that an incident has occurred and encourage them to use alternate modes, routes, or times of travel to avoid the incident area. That is why it is important to consider information dissemination strategies when developing incident management plans for work zones.