Balancing Efficiency and Equity of Ramp Meters

Abstract

An efficient ramp control strategy may not be politically attractive due to its negative impacts on equity. This paper addresses this issue and presents a new objective for ramp metering-minimizing weighted travel time-which is able to balance efficiency and equity. A quasioptimization/simulation approach is used to achieve the new objective. BEEX, a new family of control strategies with various degrees of equity consideration, are developed and used to demonstrate this approach.

Efficiency and Equity Performance of a Coordinated Ramp Metering Algorithm

“…They observed a trade-off between efficiency and fairness, which the AMOC strategy addressed implicitly with consideration of the available on-ramp storage space. Zhang and Levinson [1] proposed a RM objective function to minimize total weighted travel time, which can be used to balance efficiency and equity of RM control via weighting on-ramp delays nonlinearly. Nevertheless, they acknowledged that it was difficult to obtain an effective weighting function for on-ramp delays.…”

“…RM exerts effects on efficiency and equity performance of motorways. Efficiency benefits attributed to RM in literature [1][2][3][4] include reducing travel times, increasing motorway throughputs and decreasing fuel consumption and emissions. Travel time and throughput reflect mobility and capacity of a motorway system, respectively.…”

“…Yin et al [6] stated that the lack of consideration of inequity among road users has adversely influenced public acceptance and hindered the widespread use of RM. Zhang and Levinson [1] suggested that although improving efficiency of motorway systems is the original and still the most important objective of RM, user equity should be considered at least as the secondary goal to make it a viable system.…”

Statistical Evaluation of Ramp Metering for a Dual Free way Corridor

“…Gettman et al 10 Presented a multiobjective integrated large-scale optimized ramp metering system for freeway traffic management, seeking to address the interaction of the freeway system with the adjacent surface-street system by providing a method to trade-off queue growth at individual ramps in a freeway corridor. Zhang et al 11 Developed a new freeway ramp control objective-minimizing total weighted (perceived) travel time by balancing efficiency and equity of ramp meters, compared to a previous metering objective, which minimizes the total absolute travel time. A ramp metering algorithm incorporating "fuzzy logic" decision support was developed at the University of Washington for a number of years.…”

Safety warning based on highway sensor networks

“…Current highway warning systems have already exploited advanced sensor technologies [4] [21] [22] , such as microwave presence-detecting radar, doppler microwave radar, laser radar, active/passive infrared, ultrasound, acoustic array, magnetic, video image processor, inductive loop detector, fog sensing, etc., for intersection control [3], freeway incident detection [26], traffic congestion monitoring [16], ramp and freeway-to-freeway metering [38], lateral control [23], traffic data collection [34], weather and highway condition detection [7], etc. These systems rely on the data collected by sensors for their management and control.…”