Case Study:

Tren Urbano

Overview

This case study illustrates the measurement of regional accessibility to employment. Accessibility is measured by mode of transportation and by income group. The method can be applied using census and employment data, in conjunction with highway and transit network data from a regional travel demand model.

Working in partnership with local planning officials, the Tren Urbano Project at the Massachusetts Institute of Technology (MIT) evaluated the regional accessibility and equity impacts of a proposed rail transit system in San Juan, Puerto Rico. The impacts of the rail system were compared with the impacts of a "no-build" alternative, other transportation improvements, and land use policies to concentrate development near transit stations. The calculations were performed using a geographic information system (GIS), which permitted the graphical display of existing accessibility levels and changes in accessibility, as well as the analysis of impacts across income groups.

The study found that while the rail system will have accessibility benefits, these benefits are highly localized along the rail alignment and may not decrease the inequities in mobility among income groups. The study further found that policies to increase development in station areas would increase the accessibility benefits of the system, with these benefits distributed across all income groups.

In addition to analyzing accessibility at a regional level, the team used GIS tools to evaluate the walkability of station areas along the proposed system. A quareter- to half-mile radius is typically considered as the walking service area for a rail station. A more detailed analysis, however, shows that the actual area that can be reached by pedestrians may be much smaller than the area of the circle if direct streets or pathways are not provided (Figure 1).

Figure 1. Quarter-Mile Walking Distance, Tren Urbano Stations

Fig. 1 Quarter-Mile Walking Distance, Tren Urbano Stations

Source: Zhang, Shen, and Sussman (1998).

The regional and station-area accessibility analyses were conducted using commonly available transportation data sets and GIS analytical tools. The results suggest transportation and land use strategies that might be implemented to reduce spatial inequity and to enhance both transit and employment accessibility.

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