Ramp Metering Delivers – Again

This article describes how ramp metering, although still controversial, has been around for nearly 50 years. The article describes how ramp metering continues to deliver substantial benefits and generally for relatively small cost. The article uses Kansas City as a case in point. In March 2010, Kansas City Scout, a partnership between the Missouri and Kansas Departments of Transportation (DOTs) provides intelligent transportation system (ITS) for the greater Kansas City Area, activated the first ramp metering system in the region. The project is located on an 5.5 mile section of Interstate 435 from Metcalf Avenue to 103rd/104th Street and a total of 16 ramp metering signals were deployed on seven interchanges. Kansas City Scout, the bi-state Transportation Management Center (TMC) for the Kansas and Missouri Departments of Transportation, is responsible for the entire ITS program, incident management, motorist assist, and technology deployments. Through his creative leadership, Kansas City Scout has become one of the premier TMCs in the United States. The ramp metering project was a retrofit low-cost project to bring the proven accident reduction engineering principles of ramp metering to the Heartland. There were no ramp or interstate modifications in the implementation of the project, so the cost per intersection was kept to approximately $30,000. KC Scout also implemented a corridor adaptive approach to controlling the ramp signals with Corridor Adaptive Ramp Metering Algorithm (CARMA), an innovative software system. This means that the meters are part of a smart system that allows them to be activated based on traffic demand, but also specifically during the morning and afternoon rush hour periods. The project had three primary goals: to decrease the number of sudden weaving and braking incidents that happen as vehicles merge onto the freeway; reduce accidents and allow more vehicles to smoothly drive along the freeway; and allow more cars to use the freeway. In short, Kansas and Missouri DOTs, responding to the challenging economic times and shortfall of transportation funding, saw the technology solution of ramp metering as an effective, low-cost way to relieve congestion and provide increased safety.