A bimodal transit system for large cities: cost efficiency and environment friendliness

Abstract

This paper proposes a bimodal urban transit system with point-to-point transit (PPT) services considering the emission. PPT is designated to serve passengers with long travel distances, connecting two transport hubs with few intermediate stops. We focus on the bimodal system of FRT and PPT, formulating the joint design problem as a mixed-integer program through a parsimonious continuum model. The relative location between FRT and PPT stations varies over space, which complicates route choice analysis. We overcome the challenge by approximating the costs to access transit stations at an aggregate origin-destination level. This is validated by Monte Carlo simulation. Our findings show that the proposed system is both more cost-efficient and eco-friendly than the regular system in cities with high travel demand. However, its performance deteriorates as demand drops. Such a demand threshold is systematically examined in cities with different features such as geographical sizes, PPT speed, and income levels.

Keywords:

• PPT
• transit network design
• route choice modeling
• emission budget

Acknowledgments

The authors are extremely thankful to Jianan Zhu, who is the vice deputy director at the Road Traffic Safety Research Center in China, for his professional view on real-world transit operations in metropolitan areas.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 As of Feb 1, 2021, the official website of Optics Valley was http://www.chinaopticsvalley.com.

2 We assume that PPT can find an expressway in a relatively short time, which could be acceptable for our targeted large cities including Chicago (e.g. Interstate I90 and I94), Shanghai (e.g. South-north and Yan'an expressways), etc.

3 A portion of the travelers can use other modes to access/egress from the city center, especially when the access/egress distance is short.

4 For brevity, the derivation for the regular FRT system, as a reduced system, is ignored in the paper.

5 The choice of ${\gamma }_a$, ${\gamma }_w$ and ${\gamma }_R$ presumably represents a low-wage city.

6 As of Feb 1, 2021, the report was available at http://www.bjtrc.org.cn/List/index/cid/7.html.

7 Whatever the FRT technology is, infrastructure and vehicles of PPT are considered as equally developed as those of FRT.

Additional information

Funding

This study is supported by the Fundamental Research Funds for the Central Universities (2019RC053) and the National Natural Science Foundation of China (72001017; 71890972).