Overview
This primer poses ramp metering as a potential tool to address commonly occurring congestion and safety issues. Despite initial opposition and skepticism from various stakeholders, ramp metering has been deployed, sustained, and even expanded in many regions. This primer incorporates recent research on challenges agencies experience during their attempts to deploy or expand ramp metering in their regions. While geometric limitations of existing ramps are a common challenge, agency support and project cost s also pose difficulties for several agencies. Recent case studies provide insights into how these common challenges could be addressed as well as lessons learned. This primer emphasizes organizational capability, public outreach, and geometric limitations as key considerations when deploying or expanding ramp metering.