Evaluating the Benefits of a System-Wide Adaptive Ramp-Metering Strategy in Portland, Oregon

A System-Wide Adaptive Ramp Metering (SWARM) system is being implemented in the Portland metropolitan area, replacing the previous pre-timed ramp-metering system. SWARM has been deployed on six major corridors and operates during the morning and afternoon peak hours. This study entails a ―before‖ and ―after‖ evaluation of the benefit of the new SWARM system as compared to the pre-timed system using the existing data, surveillance and communications infrastructure. In particular, the objective of this study is to quantify the system-wide benefits in terms of savings in delay, emissions and fuel consumption, and safety improvements on and off the freeway due to the implementation of the SWARM system. A pilot study was conducted for two weeks on a 7-mile freeway corridor in an attempt to develop a strategic design for the future regional-level study. This paper discusses the selection process of the study corridor, experimental design, and the results that were obtained from the pilot study.