Integrating Travel Time Reliability into Transportation System Management: Final Technical Memorandum

Chapter 4. Tactical Program Areas

This section proposes an organizing structure for understanding the relationship between the overall strategies for transportation operations, the underlying tactical program areas, and the tactics or functions that work together to support a strategy. It also describes the implications of the tactical program areas for travel time reliability as well as how reliability data and analysis tools could be used to help implement the tactical areas.

Figure 8 depicts how the goals and objectives feed into the process of identifying strategies and tactics. This section focuses on the strategic and tactical level of the diagram. The strategies and tactics (or functions) of this framework exist within the larger methodology that translates system goals and objectives into network- or corridor-level operational objectives, which are realized by strategies and tactics.

For the purposes of this framework, management strategies are defined as the policy or "game plan" for achieving the operational objectives. The management strategies describe the overall approach for solving the issue or meeting the operational need. In this framework, the study team identified three overarching management strategies at a high level. It is possible to characterize management strategies for operations in many other ways, but this categorization is useful for further classifying tactical program areas. Other management strategies will be developed as part of the application of the methodology to the scenarios in the appendix.

The study team first divided the strategies for managing and operating the transportation system into addressing congestion that arises from events or incidents on the system and addressing base-level congestion. The team then further divided the approach to addressing base-level congestion into efforts to impact how much, when, and where demand occurred on the system and efforts to manage existing traffic on the system (figure 9). One may think of this division as distinguishing between supply and demand for transportation.

The tactical program areas represent categories of operational tactics, such as road weather management or work zone management. The study team developed these areas primarily based on the Federal Highway Administration (FHWA) Office of Operations' program areas, with some exceptions. This framework separates out those tactical areas that focus on managing demand, such as congestion pricing and travel demand management. The team added freight management to the traffic management category as a specific type of traffic to be managed. The demand management tactical program area includes congestion pricing, parking management, and those strategies that focus on increasing the use of multi-occupant travel modal options (shared-use mobility) such as transit or ride-sharing. Many of these tactical program areas overlap; for example, all of the event- or incident-related tactics are conducted in the context of managing freeways, arterials, or transit services.

The tactics or functions beneath each tactical program area are specific actions that transportation operators or managers can perform in service of an objective. Table 1 maps technologies to the tactical program areas they support. The lists of tactical program areas is not exhaustive, but is meant to be representative of some of the most common tactics associated with a program area. Some tactics cut across several program areas; for example, providing variable speed limits supports the goals of the traffic incident management and emergency transportation operations, work zone management, planned special event management, freeway management, and arterial management program areas, among others. Technology supports most of the tactics listed in the framework and tends to cluster into themes such as surveillance and monitoring systems, information dissemination technologies, and traffic control and decision support systems. These are factors that agencies can take into account when deciding which investments in management and operations will have the greatest impact or application.

Table 1. Mapping operations-related technologies to the tactical program areas they support.

	Road Weather Management	Traffic Incident Management and Emergency Transportation Operations	Work Zone Management	Planned Special Event Management	Freeway Management	Arterial Management	Integrated Corridor Management	Freight Management	Active Traffic Management	Congestion Pricing	Parking Management	Public Transportation and Ridesharing Management
Environmental sensor stations (ESS)	X
Road weather information systems (RWIS)	X
Closed circuit television (CCTV) cameras	X	X	X	X	X	X	X	X	X	X		X
Dynamic message signs	X	X	X	X	X	X	X	X	X	X	X
Flashing beacons atop static signs	X							X		X
511 systems	X	X	X	X	X	X	X	X	X
Highway advisory radio	X	X	X
Websites and smartphone apps	X	X	X	X	X	X	X	X	X	X	X	X
Decision support systems	X	X	X	X	X	X	X		X	X	X
Transportation management centers (TMCs)	X	X	X	X	X	X	X		X	X
Advanced traffic management systems (ATMS)	X	X	X	X	X	X	X		X
Signal timing plans	X	X	X	X		X	X		X
Computer aided dispatch (CAD) systems		X
Automated crash notification systems		X
Incident prediction systems		X
Safety service patrol trucks		X
Ramp meters and adaptive ramp metering systems		X	X	X	X		X		X
Signal control systems		X	X	X		X	X		X
Electronic lane control signs		X	X	X	X	X			X	X
Variable speed limit signs		X	X	X	X	X			X	X
Portable electronic traffic control boards		X	X	X		X	X
Automated queue length detectors			X	X	X					X
Emergency vehicle signal preemption system						X
Transit signal priority system						X	X					X
Electronic truck screening systems						X		X
Truck signal priority systems							X	X
Truck parking management systems								X
Electronic toll/payment/fare collection systems										X	X	X
Parking surveillance or detection systems											X

Incident and Event Management

Incident and event management includes several tactical program areas that address major sources of travel time unreliability (see figure 10).

Road weather management is a tactical program area that addresses issues related to hazardous weather. It offers tactics, such as operational response plans and variable speed limits that do not eliminate a primary cause of travel time unreliability—poor weather—but have the potential for reducing the impact of weather on travel time reliability. Agencies can collect historical information on weather from the National Oceanic and Atmospheric Administration (NOAA) or commercial websites. This information can be communicated to the public through road weather information systems (RWIS) or used to predict travel time unreliability during operational planning.

Traffic incident management and emergency transportation operations offers a set of tactics to address crashes, non-crash incidents, and other emergency situations. These events can create unexpected delays and contribute to unreliability. Tactics such as traffic incident management (TIM) teams and pre-staged tow trucks allow authorities to clear crashes faster and return roadways to typical operations. Variable speed limits, dynamic lane control, and hard shoulder running allow agencies to take advantage of available infrastructure to prevent unusual travel conditions from worsening. For planning purposes, law enforcement often collects crash records and shares them with transportation agencies. Traffic management centers can collect incident management information, such as dispatch logs, that can be used in planning operational responses to disruptions.

Work zone management allows agencies to control and limit the unexpected delays that work zones impose on travelers. Tactics such as temporary ramp metering coupled with network surveillance help to improve travel time reliability. Agencies can use historical information from construction administration and traffic management incident logs related to road work as inputs in planning future work zone management and in selecting tactics to address traffic impacts.

Planned special event management helps to lessen unexpected delays imposed on travelers not participating in the event as well as improve the travel experience for participants. Special event signal timing plans allow agencies to address the unusual demands associated with special events, while after action reviews promote learning from previous actions. Tactics such as adaptive ramp metering, hard shoulder running, and reversible lanes allow agencies to maximize the use of available infrastructure, while dynamic pricing, wayfinding, and transit pricing work to match travel demand to the available supply. Agencies should share information on planned special events at major neighboring facilities as part of travel time reliability planning.

Traffic Management

While incident or event management strategies address atypical events that cause travel time unreliability, traffic management strategies manage the movement of people and goods during everyday conditions (see figure 11). Even during typical conditions, fluctuations in travel demand can lead to unreliable travel conditions. Traffic management strategies allow the transportation network to adapt to unreliability, including variations in travel demand.

Freeway management and arterial management provide tactics tailored to freeways and arterials, respectively. Tactics such as adaptive ramp metering and enhanced signal timing help agencies use existing infrastructure to respond to unusual peaks in demand. Other tactics, such as truck-only lanes and transit signal priority support improved travel time reliability for goods movement and for transit modes. Historical data on travel times collected by sensors or probe vehicles can help agencies plan operational responses to unreliable travel on freeways and arterials.

Active traffic management offers a more robust response to changing traffic conditions. Tactics like dynamic lane use, hard shoulder running, and dynamic warning signs allow agencies to modify the available supply of roadway infrastructure to current conditions, particularly changes in travel demand. These tactics can work in tandem with incident and event management tactics to address other causes of unreliability, such as weather, special events, and incidents. Active traffic management requires detailed data on current traffic conditions, short-term forecasts of future conditions, and predictions of how traffic responds to tactics based on historical data.

Integrated corridor management tactics leverage the capacity available across modes to better match infrastructure with travel demand. These tactics can be adaptive and allow agencies to respond to travel time unreliability. Many of the tactics in use by agencies deploying an integrated corridor management (ICM) initiative support other tactical program areas. ICM tactics require data from transit agencies and other modes.

Freight management tactics provide options for freight handlers and carriers to mitigate unreliable travel conditions for both trucks and other travelers. For example, truck signal priority makes last-mile freight travel more reliable, and truck climbing lanes reduce delay impacts to other vehicles. Tracking logistics information, data on freight flows, and detailed information on freight networks help with planning for freight management.

Demand Management

Demand management provides tactics that reduce underlying demand by helping travelers avoid trips or change the mode, timing, or route of trips (see figure 12). This makes non-recurring congestion less likely to occur and improves travel time reliability.

Congestion pricing offers dynamic tactics that make travel on roadways less attractive or alternative modes more attractive in response to demand. This allows transportation infrastructure to accommodate variations in demand, resulting in more reliable travel times. Congestion pricing requires detailed information on traffic and demand elasticity estimates. High occupancy toll and managed lanes require additional information on vehicle occupancies, while dynamic transit fare reductions require data on transit fares, schedules, and capacity.

Parking management matches parking supply to fluctuations in demand. These tactics are generally not related to travel time reliability, but dynamically priced parking can moderate variations in travel demand, which is one cause of travel time unreliability. Effective parking management requires information on parking availability and demand.

Public transportation and ridesharing management provides modal alternatives to single occupant vehicle travel. While these strategies do not address the causes of travel time unreliability directly, they can help to reduce demand during high peak periods. Implementation requires data on traveler origins and destinations, desired travel times, and transit schedules.