| Summary |
Ramp metering is the most effective measure for freeway traffic management. The flow from the ramp to the mainline is controlled through the traffic light installed onramp to maintain the operation of the mainline and avoid the mainline from entering traffic breakdown. Ramp metering technology has been widely implemented on freeways in Taiwan, but freeways still often have traffic congestion. Therefore, it is necessary to examine the current implementation of ramp metering and the degree of
improvement in freeway operation performance.
This research aims to explore the impact of ramp metering on the operating performance of the bottleneck section of freeway merge areas. Because the effect of ramp metering is related to ramp metering strategies, implementation methods, and timing of use. The study collects history metering rate and vehicle detector data and evaluates performance with or without ramp metering to mainline through the transition period, average speed, average flow, and maximum flow rate. After collecting these parameters, we propose a hypothesis method to examine different locations and different periods of congestion with or without ramp metering. Our results show that the improvement to average flow and average discharge flow are significant, whereas the improvement of transition time and average speed are not significant. If ramp metering can successfully avoid the occurrence of congestion, the maximum flow rate before the traffic breakdown will be significantly increased. However, it has also been found that ramp metering can’t avoid the occurrence of traffic congestion, or the ramp metering is activated after the congestion occurs, which can’t increase capacity
significantly. In addition, the study uses the stochastic capacity analysis method to explore whether the capacities of different congestion periods are affected by the ramp metering strategy. It is found that the capacity are generally improved with ramp metering. But in some cases it is found that ramp metering is implemented after traffic |
