Analyzing the effectiveness of ramp metering in alleviating crash-related congestion on freeways

Ramp metering signals (RMSs) are usually activated to reduce recurrent congestion. Ramp metering could also minimize the non-recurrent congestion due to traffic incidents. While recurrent congestion depends on the time of day, non-recurrent congestion due to incidents depends on several other factors, including incident duration, lane blockage, and responding agencies. This study evaluated the impact of ramp metering on non-recurrent congestion due to crashes. The study was based on crash, traffic, and RMSs operations data from 2016 to 2018 collected on a section along I-95 in Miami-Dade County, Florida. Results showed that activating the nearest upstream RMS positively influenced traffic conditions upstream of a crash location during daytime off-peak periods. Factors including the extent of lane blockage, type of lane blockage, number of responding agencies, incident detection methods, and fire rescue influenced the traffic conditions upstream of the crash location during daytime off-peak periods and peak periods.