California Partners for Advanced Transportation Technology

PeMS is a freeway performance measurement system for all of California. It processes 2GB/day of 30-second loop detector data in real time to produce useful information. Managers at any time can have a uniform and comprehensive assessment of freeway performance. Traffic engineers can base their operational decisions on knowledge of the current state of the freeway network. Planners can determine whether congestion bottlenecks can be alleviated by improving operations or by minor capital improvements. Travelers can obtain the current shortest route and travel time estimates. Researchers can validate their theory and calibrate simulation models.

PeMS is a low-cost system. It uses the Caltrans network for data acquisition. It is easy to deploy and maintain. It takes under six weeks to bring a Caltrans district online. Functionality can be added incrementally. PeMS applications are accessed over the WorldWide Web. Custom applications can work directly with the PeMS database. PeMS has been in stable operation for 18 months. Built as a prototype, PeMS can be transitioned into a 7x24 production system. The report describes the PeMS architecture and use.