Executive Summary

Departments of Transportation control the apportionment of tax dollars to build and operate the transportation system which people use to connect to their destinations. The ways that people and businesses use the system on a daily basis and through long-term investments shape the land uses and built environment of our communities. In common practice, however, evaluating how transportation investments shape land use is not part of the planning or evaluation of transportation projects. Rather, the movement, speed, and especially delay of cars and trucks is the primary measurement by which agencies and the public evaluate transportation network success. To accurately measure the impacts generated by the actions of these Departments of Transportation (DOTs), changes to land use and land value that result from changes to the transportation network must be included. 

In the following pages, we argue for the use of Accessibility measures in system performance and project prioritization for DOTs, to fully account for DOT decisions. Accessibility, a measurement of how easily people can connect to their desired destinations, is not a new concept, yet progress has been slow in adopting measures which focus on people rather than vehicle movement and delay. To spur further consideration, we document the theoretical and practical basis for Accessibility, describe available data, explore change in metrics over short and long time scales, and recommend approaches for inclusion into DOT decision making. Ultimately the impact of DOT actions cannot be fully captured by the vehicle movement metrics which comprise the status quo. Accessibility metrics offer a way to evaluate the destination opportunities DOT projects provide, who they serve, and how they change land use over the short- and long-term.

Transportation can connect people with jobs and other economic opportunities, health care, education, recreation and all the other necessities of a full life. The level of this access can be quantified. Using accessibility metrics we can measure the progress of DOTs toward connecting people to essential quality of life destinations. Knowing the speed and delay of the average auto trip on the average day is no longer enough. It is time for DOTs to measure what matters. Our transportation systems are primarily there to provide access. Measuring how easily people can reach the destinations they need offers DOTs the opportunity to build projects that account for all travel choices, improve our collective quality of life, and benefit our economy.