Managing Congestion with Integrated Corridor Management

The Analysis, Modeling and Simulation (AMS) methodology used historical data from the test corridor to examine the potential implications of specific ICM strategies — such as adaptive ramp metering, traffic signal coordination, transit traveler information, highway traveler information, high-occupancy toll (HOT) lanes and combinations of these — under a variety of conditions, including medium and high travel demand, and with both a minor and a major incident along the corridor in each travel demand scenario. By using multiple ICM strategies, both separately and in combination, the team tested the AMS methodology comprehensively in terms of traveler response (route diversion, mode shift and temporal shift) and tested the interfaces for the flow of data among the modeling tools that were used. The test corridor experienced a 4 percent mode shift under high demand with a major incident when transit traveler information was provided (e.g., expected traffic delay, transit options, transit schedules, real-time parking availability).

ICM and Transit
Public transit is ideally suited to help increase capacity and improve passenger flow in congested transportation corridors. Transit, along with transit ITS technologies and strategies, will play a significant role in ICM, which is described by Pioneer Sites as “the next logical step for our nation’s corridors.” Transit often has underutilized capacity in corridors. Transit ITS technologies and strategies improve transit operations and service, making transit more appealing. Transit will serve two primary roles within ICM: balancing travel demand load during routine traffic conditions, such as recurring congestion and shifting the capacity burden from roads during major incidents, construction and special events to alternate modes and routes.

“The Federal Transit Administration [FTA] is committed to supporting integrated corridor management,” says Walter Kulyk, director of FTA’s Office of Mobility Innovation. “Transit can offer additional corridor capacity and provide an option for travelers during normal operations and during planned and unplanned events. Also, transit ITS technologies increase transit flexibility, efficiency and convenience for travelers.”

Balancing Travel Demand during Routine Traffic Conditions
Through various ITS strategies, such as transit signal priority (TSP) and BRT, transit can improve its travel times and trip time reliability, and thus make itself a more attractive and reliable option. Improved reliability of transit will encourage people to shift modes and thereby reduce the number of cars on the roads and improve overall traffic conditions.

TSP is an operational strategy that facilitates the movement of transit vehicles, usually buses and light rail vehicles, through traffic-signal controlled intersections. TSP can be implemented in a variety of ways; priority treatments include passive priority, early green (red truncation), green extension, actuated transit phase, phase insertion, phase rotation and adaptive/real-time control. BRT combines infrastructure and right-of-way design, new vehicle concepts and ITS transit technologies to provide high-quality rail transit while maintaining the flexibility of on-street bus operations. Houston, Minneapolis, Oakland and San Diego plan to use BRT within their corridors.

Shifting Demand from Roads during an Incident
In order to meet the unanticipated needs of travelers during a major incident and encourage mode shifting, corridor agencies must inform the public of the incident as well as advise travelers of their options, and transit agencies need to be able to accommodate the additional demand without much prior notice.

Corridor agencies must provide real-time, multimodal traveler information to the public to allow them to make informed trip decisions. A multimodal traveler information system would provide pre-trip and en-route information to travelers on roadways, transit (e.g., routes, schedules, fares) and parking (e.g., locations, number of parking spots, costs) via multiple outlets and media. Real-time information should be provided on traffic conditions (e.g., traffic speeds or travel times, road closure or construction locations and status, major incidents and delays, weather), transit conditions (e.g., closure or construction locations and status, major incidents and delays, real-time schedule status, projected transit vehicle arrival times), and parking availability. Web-based multimodal trip itinerary planning services that provide directions, travel times and costs to travelers for a trip from point A to point B for different roadway/transit route options could be included.