Timothy F. Welch^a,
Sabyasachee Mishra^b, ^c,
^a Center for Quality Growth and Regional Development, Georgia Institute of Technology, School of City and Regional Planning, 760 Spring Street, Suite 213, Atlanta, GA 30308, United States
^b Intermodal Freight Transportation Institute, University of Memphis, 302 Engineering Sc. Bldg., Memphis TN, 38152, United States
^c University of Memphis, Department of Civil Engineering, 104 Engineering Science Building, Memphis, TN, 38152, United States


Highlights

•We develop a methodology for transit equity estimation.
•The methodology is applied to demonstrate the proposed approach in a simplified example problem.
•Examines multi-modal transit network equity in the Washington–Baltimore region.
•Provides a tool to measure how changes in service affect equity.


Keywords
Transit equity; Graph theory; Capacity; Frequency; Multi-modal transit


Abstract
An equitable transit system can cater to the needs of captive riders and maximize transit service coverage. Historically transit equity has not considered in planning or has been an afterthought in the process; leading to the underutilization of transit and encouraging travelers to be auto dependent. In this paper, the authors propose a methodology to estimate transit equity using a number of attributes such as frequency, speed, capacity, and built environment in a multi-modal transit network. We propose a methodology to measure transit equity from a graph theoretical approach for all levels of transit service coverage integrating routes, schedules, socio-economic, demographic and spatial activity patterns.The objective of using equity is to quantify and evaluate transit service in terms of prioritizing transit locations for funding; conforming with federal regulations; providing service delivery strategies, especially for areas with large multi-jurisdictional, multi-modal transit networks; providing an indicator of multi-level transit capacity for planning purposes and assessing the effectiveness and efficiency for node/stop prioritization while choosing transit as a mode of travel. The methodology uses a stylized connectivity measure with a Gini index for equity estimation at different levels such as stop, line, zone and area. An example problem is presented to demonstrate the proposed methodology. The approach is then applied to the Washington–Baltimore region in the United States. The results show the existing transit service coverage at different locations. The proposed approach can be utilized as a tool for transit service planning.


Article Outline
1. Introduction
2. Related literature
2.1. Measures of equity
2.2. Measures of supply

3. Methodology
3.1. Connectivity
3.2. Transit catchment and accessibility
3.3. Inequality index

4. Example problem
4.1. Connectivity
4.2. Inequality index

5. Case study
6. Results
7. Summary and conclusion
. Appendix A
References


Figures
   

Fig. 1.

Zonal transit catchment. Source: Created by Authors.


Fig. 2.

GINI index example. Source: Created by Authors.


Fig. 3a.

Example of transit system and zones. Source: Created by Authors.


Fig. 3b.

Walking distance to transit nodes in each zonal catchment. Source: Created by Authors.


Fig. 4a.

Transit routes in Prince George’s County. Source: Created by Authors.


Fig. 4b.

Transit routes in Baltimore. Source: Created by Authors.


Fig. 5.

Locations of equity analysis. Source: Created by Authors.


Fig. 6a.

Connectivity index at the zone level. Source: Created by Authors.


Fig. 6b.

Connectivity index for Prince George’s. Source: Created by Authors.


Fig. 6c.

Connectivity index for Baltimore. Source: Created by Authors.


Tables

Table 1. Example problem characteristics.

Table 2. Sample problem connectivity results – nodes.

Table 3. Sample problem connectivity results – zones.

Table 4. Inequality Index of the Connectivity Distribution.

Table 5. Transit inequality index by location.