Abstract:
Metering aims to improve traffic flow on the main lanes of a freeway by regulating the inflow to these lanes. While metering is most often implemented at on-ramps to a freeway, it can also be used to regulate the flow of traffic on the main lanes themselves. Although counterintuitive that regulating flow on the main lanes can also improve overall traffic flow, this can happen in cases where downstream bottlenecks exist. Alternatively, upstream metering may simply be required to prevent excessive queuing at a downstream bottleneck. This paper evaluates two metering techniques applied to the eastbound main lanes of Interstate 70 at the Eisenhower–Johnson Memorial Tunnel (EJMT) to potentially improve traffic flow, shorten the queues both east and west of the EJMT, and reduce the need to completely stop traffic at the EJMT. One strategy evaluated is traditional, or manual, metering in which operations staff stop and start traffic as seen necessary to reduce a downstream queue. The other strategy is called continuous flow metering (CFM), which automatically displays red and green lights at a given cycle length to smooth out the traffic stream as well as reduce downstream queuing. The study results show that CFM did reduce travel times and save person hours of travel in several trial time periods.
