The National Academies

TCRP H-41 [Final]

Assessing and Comparing Environmental Performance of Major Transit Investments

  Project Data
Funds: $400,000
Research Agency: Cambridge Systematics
Principal Investigator: Christopher Porter
Effective Date: 12/24/2009
Completion Date: 3/1/2012

Building on a the colloquium, “Comparing the Environmental Benefits of Transit Projects,” conducted by the Volpe Center (October 2008), the following considerations are important to developing criteria, metrics, and methods for assessing and comparing environmental performance of transit projects: 
  • Public and political understanding and acceptance of environmental performance criteria will be greater if such criteria are intuitively correct and transparent.
  • As much as possible, the criteria for assessing and comparing environmental performance should be based on data and methods readily available, easily attainable, and generally accepted by project sponsors. Where new data and methods are needed, the contractor for this research should remain mindful of financial and staffing requirements of project sponsors. The environmental performance of a proposed transit project may be computed many times during project development. Computing highly complex measures of environmental performance can be relatively expensive.
  • The criteria and methods should be generally applicable to all types of regions, ranging from densely developed areas with extensive transit networks to low-density environments with limited transit infrastructure. This approach recognizes differences in changes in environmental performance that may result from transit investments.
  • The criteria must be applicable to various transit technologies (e.g., heavy rail, light rail, commuter rail, ferry, streetcar, and bus rapid transit) and various project lengths, in various locations and metropolitan areas. The criteria must account for the size of the investment (i.e., performance may be different for a $300-million project than for a $5-billion project).
  • The criteria should clearly distinguish transit projects that are more environmentally beneficial from those less beneficial, while recognizing that a project can be environmentally beneficial without demonstrating a change in environmental performance because it supports existing sustainable development.
  • Although quantitative methods and metrics are preferable, qualitative criteria of evaluating environmental performance may, in some instances, be more appropriate.
  • The criteria, metrics, and methods for assessing and comparing environmental performance should, where possible, be able to be compared against a baseline alternative, including the New Starts Baseline alternative and the No-Build alternative.  Some criteria, metrics, and methods may best be applied using one of the baselines noted above or another baseline identified by the researcher.  Substantial differences among the baselines (e.g., data availability) should be noted.
  • Although many factors may be considered, some practitioners have indicated a preference for a process that develops a single rating for environmental performance.  
  • A transit project’s poential environmental disbenefits should also be taken into account. Disbenefits may encompass externalities or social costs to the environment. For example, a transit project that requires numerous, large park-and-ride lots for access by private automobile may or may not be beneficial to the environment.
The objective of this research is to present, evaluate, and demonstrate criteria, metrics, and methods for assessing and comparing the environmental performance of major transit investments. The research results should offer a basis for assessing and comparing these transit projects and should offer project sponsors optional criteria, metrics, and methods for assessing transit projects with regard to environmental performance.  (Although the National Environmental Policy Act (NEPA) process may be a source of information for the environmental criteria, this research focused on environmental performance assessment and comparison, not environmental impact analysis.)
STATUS: The project was completed in January 2012.

The executive summary was published in May 2012 as TCRP Research Results Digest (RRD) 105.

The full report was published in May 2012 to the TRB website as Web Only Document (WOD) 55.

To create a link to this page, use this URL: http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=2616