Lead Presenter Biography

Siwei Hu is a 4th year PhD student majoring in Civil and Environmental Engineering (transportation systems engineering) at University of California, Irvine. He completes his bachelor’s degree in Traffic Engineering in Sun Yat-sen University in China in 2019. His research interests include transportation network modeling, activity-based travel demand modeling, congestion pricing mechanisms in transportation. He serves as the president of the Institute of Transportation Studies – Graduate Student Association (ITS-GSA) at UC Irvine in the academic year of 2022-2023. He receives many awards and scholarships, including Division of Teaching Excellence and Innovation (DETI) Summer Fellowship at UC Irvine in 2020, Outstanding Youth Achievement Award from Chinese Consolidated Benevolent Association in 2022, and the ASCE-OC Transportation Vision Scholarship in 2022.

Co-Authors

Presentation Description

Equity plays a more and more important role in evaluating the transportation systems. The goal of achieving transportation equity is to fairly distribute the benefits and cost of the transportation system to its users. Four key questions in transportation equity research, modeling, and planning are: (1) what is transportation equity? (2) what are the benefits and costs to be distributed? (3) how to categorize persons and population groups? (4) what distributive principle should be used to distribute or redistribute benefits and costs to achieve an equitable state?

To answer these questions, researchers have studied different metrics to quantify transportation equity and factor them into transportation planning and analysis processes. Common metrics used in transportation equity analysis include those that relate to accessibility to key activities, travel affordability, safety, etc. Although they are good equity indicators for the transportation planning process (e.g., 5-10 years of planning time period), these metrics are not suitable in transportation operations (e.g., traffic management and control in the morning peak). It is because these metrics change only when transportation infrastructure changes (e.g., a new transit line), but once the infrastructure is built or changed, such metrics remain relatively constant. These metrics cannot guide transportation planners and engineers in making operational decisions that are equitable. So, it is necessary for them to adopt an appropriate equity metric to design more equitable operational strategies.

Envy, a term originating from the fair division problem in economic welfare theory, could be a good metric to quantify inequity at the operational level. A person feels envy if he/she finds that an option assigned to (or selected by) other travelers provides a higher value than his/her current selected option, based on his/her own value functions and not the other travelers’. Based on envy, the equitable state at the operational level occurs when nobody is envious of anyone else, i.e., an envy-free state.

In this study, envy is adopted to design route choice management schemes. We develop a platform where travelers can coordinate their route choices with monetary exchanges. The system optimal routes are calculated as travelers’ choice set, and the monetary exchanges are calculated to minimize envy among all travelers, considering their heterogeneity in value of time. We test this platform in the Los Angeles I-10 toll expressway corridor network with 799 nodes, 1,927 links and 78,196 trips. The results show that with as little as 5% of travelers engaging in peer-to-peer route choice coordination with monetary exchanges, the transportation system can achieve a system optimal and equitable envy-free state. Moreover, the envy-based peer-to-peer exchanges can also yield a higher level of traveler satisfaction among different income groups and equity across the traveler population.

This study shows that envy, as a transportation equity metric, could guide planners and engineers to make more equitable decisions at the operational level (e.g., envy-free route coordination management schemes). More application scenarios of envy-based management schemes will be explored in the future work. 

Presentation File