Knowledge Resources

A 2010 study used the USDOT Analysis, Modeling and Simulation (AMS) framework to evaluate the impact of implementing Integrated Corridor Management (ICM) on the Interstate-15 Corridor in San Diego, California. Serving as one of the pioneer sites in the ICM initiative, the I-15 Corridor consists of an 8 to 10 lane freeway that services commuting trips, regional traffic in off-peak hours, and interstate commercial traffic. The AMS study assessed the impacts of ICM on the I-15 Corridor under high, medium, to low travel demand, and during daily operations and freeway and arterial incidents. The study tested the following ICM strategies: pre-trip and en-route traveler information, mode shift to transit, freeway ramp metering, signal coordination on arterials with freeway ramp metering, physical bus priority, and congestion pricing on managed lanes.

Methodology

The modeling approach chosen came from an analysis of capabilities found in existing AMS tools and from the ICM Test Corridor project. The approach was an integrated platform that supported corridor management planning, design, and operations by combining the capabilities of existing tools. The overall integrated approach was based on interfacing travel demand models, mesoscopic simulation models, and microscopic simulation models.

The AMS methodology applied includes the macroscopic trip table manipulation for the determination of overall trip patterns and mesoscopic analysis of the impact of driver behavior in reaction to ICM strategies (both within and between modes) and a microscopic analysis of the impact of traffic control strategies at roadway junctions (such as arterial intersections or freeway interchanges.) The methodology also includes the development of interfaces between different tools, and the application of a performance measurement and benefit-cost module.

Findings

The results estimate that the deployment of ICM will have a benefit-to-cost ratio of 9.7:1 over a 10-year life cycle. The benefits found as a result of the analysis include annual reductions of

• 245,594 vehicle-hours of travel.
• 322,767 gallons of fuel consumption.
• 3,057 tons of vehicle emissions.

The AMS indicates that the ICM benefits will occur over all operational conditions, improving travel time, travel time reliability, and fuel savings on the southbound freeway and arterials. In addition, providing improved traveler information is expected to attract more arterial drivers to the freeway, resulting in improvements in arterial and overall system performance.

The analysis validated the hypotheses that ICM will be most effective in the worst operational conditions due to the finding that ICM strategies produce more benefits at higher levels of travel demand and during non-recurring congestion. Specifically, 93 percent of the benefits result from the high- and medium-demand scenarios, and two-thirds of the benefits are attributed to high- and medium-demand incident scenarios. The AMS identified a disbenefit from managed lanes in which the lanes are opened to all traffic during major freeway incidents.