Evaluation of the effects of ramp metering on merging operations

Abstract

Merging on motorways represents one of the most difficult and dynamicmaneuvers of all driving subtasks. Merging operations at uncontrolledramp junctions have been extensively investigated. With the rapid implementationof ramp metering techniques, many junctions are now operatedunder ramp metering control. Little research has been done toinvestigate the possible effects of ramp metering on the merging operation.The research described in this paper focuses on the comparisons ofmerging operations under both metered and unmetered scenarios. Timeseries data of the merging process were collected with the TransportationResearch Group instrumented vehicle and video cameras at a taperedmotorway merge site. The data included accurate vehicle speed measuredby laser speedometer, leading and following headway measuredby radar, and driver’s eye movement derived from an in-car camera.Following a comprehensive analysis of the data, it was found that mergingoperations under ramp control could be significantly different fromfree merging. Merging maneuvers may become more difficult as a resultof ramp control. The equity implications of such effects are discussed. Itis believed that the understanding gained from this research will beuseful for the design and operation of ramp metering