Researchers examined recurring and nonrecurring (incident–related) operational conditions using three levels of analysis: macroscopic, mesoscopic, and microscopic. The macroscopic analysis examined trip tables to evaluate overall trip patterns. The mesoscopic analysis examined driver behavior to evaluate traffic response to different ICM strategies, and the microscopic analysis examined the impacts of traffic control at roadway junctions.
The Analysis, Modeling, and Simulation (AMS) framework enabled cost-effective ICM strategies to be identified and evaluated on the ICM Test Corridor. The methodology was found to be robust and flexible enough to support the planning and evaluation activities on other major transportation corridors. In view of applying AMS to other Pioneer Corridors, the following guidance was provided:
- Be prepared to significantly modify the analysis framework and customize macroscopic, mesoscopic, and microscopic models to address different priorities on different corridors. Depending on the scope, complexity, and questions to be answered within a specific corridor, there may be more or less emphasis on each type of network analysis. Currently, there is no single model available that provides visibility into the cascading impacts of various congestion management strategies, much less combinations of strategies, across the entire network, transportation modes, and facility types; thus, an integrated approach is recommend that focuses on interfacing between the three classes of simulation models. In the Test Corridor, one of the primary goals was to measure the impacts of ICM on the performance of alternate routes and alternate transportation modes in the vicinity of high frequency incident sites during medium and high travel demand scenarios. All three classes of simulation modeling were proposed. In addition, researchers discussed applications for parametric simulation, time-of-departure choice, and pivot-point mode shift models.
- Consider the impacts of data quality on model calibration. Although the AMS framework is flexible and allows for the application of different types of models at the Pioneer Sites, limitations in all three locally available software programs (macroscopic, mesoscopic, and microscopic) may present challenges. Use available data. Depending on the availability of data, accuracy of model calibration can be impacted.
The utility of the AMS methodology was validated on the test corridor. All affected modes, facility types, and jurisdictions were accounted for, and the potential impacts of individual and combined ICM strategies were measured under a variety of operational conditions. Overall, HOT lanes and highway traveler information systems were found to be the most effective ICM investments. In addition, researchers noted that the effectiveness of ICM strategies varies under different prevailing conditions and that the benefits derived from a combination of some ICM strategies may be less than the benefits resulting from some individual strategies. For example, freeway ramp metering can produce positive benefits under high travel demand, but negative benefits under medium travel demand.
The AMS framework used in this study was designed to help decision-makers identify gaps, determine constraints, and invest in the best combination of strategies to improve performance. In addition, AMS provides a long-term capability enabling corridor managers to continually improve implementation strategies based on experience.