but decision makers and the public are not sure how much confidence they can have in those answers. A second barrier is the sheer number of special-purpose analytical products now available. In effect, data are run through a chain of black boxes to yield an answer. The SHRP 2 products will be introduced into this environment, adding a case-based approach to the various existing analytical approaches. Extra effort will be necessary to demonstrate the reasonableness and transparency of the SHRP 2 tools.

SHRP 2 Capacity research represents a bold effort to reimagine the way highway projects are planned and prepared for and to provide innovative tools that support the new approach embodied in the CDMF. Achieving the objectives of this research is critical to meeting mobility needs in the 21st century in a socially and environmentally responsive manner. The barriers to successful implementation are not trivial, but it is difficult to imagine how highway capacity can be provided effectively without adherence to a framework such as that described here. The availability of sufficient resources to integrate this framework into capacity planning at all levels will be critical to its successful implementation.

TRB Transportation Research Board

Brown, J. W. 2006. Eco-Logical: An Ecosystem Approach to Developing Infrastructure Projects. Report FHWA-HEP-06-011. Federal Highway Administration, Washington, D.C., April.

System Metrics Group, Inc., Cambridge Systematics, Inc., Economic Development Research Group, Inc., HLB Decision Economics, Inc., and Judd Associates. 2006. California Bypass Study: The Economic Impacts of Bypasses, Volume 1: Planning Reference. California Department of Transportation, Sacramento, May. www.dot.ca.gov/hq/tpp/offices/ote/studies_files/Bypass_Final_Report_1_v3.pdf.

TRB. 2007. Special Report 288: Metropolitan Travel Forecasting: Current Practice and Future Direction. National Academies, Washington, D.C.