Before and After Study of Ramp Metering in Kansas Revealed Crash Reduction Range of 54.8 to 83.3 Percent.
Ramp Metering Study Found Safety and Mobility Benefits for Kansas City Deployment.
Kansas City, Kansas, United States
Evaluation of Ramp Metering Effectiveness Along the I-35 Corridor in the Kansas City Metropolitan Area
Summary Information
Ramp metering is commonly utilized by transportation agencies to control freeway access and increase operational benefits. This strategy controls access to specific ramps or regulates the rate at which vehicles enter a freeway. This study investigated the safety and operational benefits of ramp metering at six merge junctions along the I-35 corridor in the Kansas City metropolitan area. A before-and-after study was conducted to compare various performance measures, such as number and types of crashes, speed, demand, and travel time changes in the vicinity of the studied merge junctions. The “before” period was selected as August to December 2015 and the “after” period was taken as October 2021 to February 2022.
METHODOLOGY
In this study, traffic flow, occupancy, speed data and the ramp metering settings were provided by KC Scout, a bi-state initiative between the Missouri and Kansas DOT, the crash data were provided by the Kansas DOT. The crash data along I-35 were analyzed to investigate the number of crashes that occurred within the influence area as a function of crash types that commonly occur at freeway merge segments, such as rear-end, sideswipe, and angle-side impact.
FINDINGS
- The results revealed a crash reduction range of 54.8 to 83.3 percent across five studied junctions, with one junction remaining unchanged.
- Crash rates expressed as crashes per 100 million vehicle-miles traveled also decreased with an average of 56.4 percent (in a range of 13 to 82.5 percent) at most junctions, except for one, where the crash rate increased by 5.8 percent due to reduced traffic volumes.
- Most locations had increased speeds, and locations that previously experienced recurring congestion became uncongested during peak hours. Average speed gains without significant flow rate changes were observed at four junctions ranging from 30.6 to 39.5 percent during the morning peak hour and 20 to 72.8 percent during the afternoon peak hour.
