Case Studies of Multiple Freeway Corridors in California Using Traffic and Incident Data Provided Insights For Large Scale Traffic Management and Facilitating Multiple Corridor Management Efforts.
Los Angeles, California, United States
San Diego, California, United States
Orange County, California, United States
Multiple ICM Management: Task ID 3706 (65A0764) - Final Report
Summary Information
Integrated Corridor Management (ICM) is an approach developed to proactively observe and identify atypical recurrent and nonrecurring events affecting traffic flow on highly congested highways and freeways within a specified corridor. It is designed to envision corridor managers to supervise corridor operations, collaborate with partner organizations and enhance multi-agency planning efforts. This study investigated the interactions between multiple corridors and the effects of incidents and response plans on adjacent or multiple corridors. Thirteen case studies were conducted on multiple freeway segments with a range of topologies, congestion patterns, and differing options for alternate paths in Los Angeles, San Diego, Sacramento, Stockton, Orange County, Fremont and Milpitas in California. Several types of data were examined, such as traffic flow, speed, travel time and incident records in 2019 from PeMS, INRIX and other third-party data providers. The objective of the study is to gain insights about how an incident may influence a large region and route choices among multiple highways. The study summarizes lessons learned and develops recommendations and strategies for large-scale traffic management and facilitating collaborations between multiple ICMs.
Some key lessons learned and recommendations for large scale traffic management across multiple ICMs are listed below:
- Have a basic level of data, data exchange, and situational awareness capabilities and establish effective standards to support large-scale data volumes and data exchange. The integration of traffic management system data across geographical regions as large as one state requires a large scale of messaging and communication systems. For example, this project estimated a daily data size of 16.4TB for signal communication when using JSON messages. Cloud technology is recommended to be considered as it can handle and process state-scale data volumes. Solid standards should be established to enable effective data sharing and exchange between systems and regions.
- Use a scalable structure to organize multiple ICMs. A scalable structure which can implement multiple response planes to manage multiple incidents on a regional scale is needed to support the vision of multi-jurisdictional collaboration for traffic management.
- Predetermine quantitative metrics to evaluate the benefit of ICM. For freeway incidents, common metrics may include flows, travel times on the freeway and alternative routes, area-based statistics, route-based statistics, and freeway queue length. Some of these metrics can be estimated using a simple historical model of freeway flows and capacity reductions due to blocked lanes, which helps bypass the need for detailed simulations.
- Identify the boundary of situational awareness and control in the deployment of response plans. This study found the effects of rerouting can be geographically large and unaccounted effects may appear and go beyond the boundaries if ICM projects are narrowly deployed along corridors within 1-2 miles. Therefore, it is important to identify the geographical boundary of situational awareness and control, which may be expanded to include freeways and arterials potentially affected by an incident or a control strategy deployed to mitigate such an event.
- Consider generating scorecards for all possible response plans with the consideration of constraints in the decision-making process. The response plans should consider the cases where multiple incidents are active and thus should include both operationally constrained and conflict constrained choices. Scorecards are suggested to be designed and generated based on all possible solutions to allow comparisons.
- Need a priority scheme to resolve conflicts in Changeable Message Signs (CMS) messaging. Conflicts may exist in CMS message requests across multiple ICMs, a priority scheme is needed to resolve these conflicts and allow for coordination.
