Document Type

Article

Publication Date

9-2022

Keywords

express lanes, equitable discounts, congestion pricing, transportation equity

Abstract

Express lanes mitigate traffic congestion by providing a time-reliable alternative and exploiting travelers' willingness to pay to generate revenue for infrastructure projects. Over the last decade, equity and fairness issues for express lanes have been considered; however, there is a lack of guidance on the design of equitable discounts. In this article, we present a modeling framework for the analysis of equity issues with express lanes for tolls optimized for different objectives. Through simulation-based optimization of tolls using reinforcement learning, we show that the choice of dynamic tolls impacts the delay differentials across different groups. We find that higher toll values and higher demand worsen the delay differentials across travel groups. We also prove that discounts proportional to travelers' value of time address delay differentials across the travel groups, where the optimal discounts may be a function of current toll and travel time savings. The analysis of tradeoffs between equity, revenue, and delay reveals that equitable discounts may result in up to 34% loss of revenue and up to 9% increase in delay. Research findings suggest (a) designing discounts proportional to VOT which can be correlated with income groups and (b) balancing the tradeoffs by carefully identifying the agency's priorities.

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