"The objective of this project is to assess methods for defining and measuring mobility in metropolitan regions. How an agency or jurisdiction defines and measures mobility greatly determines selection of strategies and ultimately investment decisions. In metropolitan areas, measuring mobility at the system level is often limited to the measure of traffic congestion and resulting delay on the freeway and signalized arterial networks. Although traffic congestion does inhibit mobility, it alone may not be a sufficient measure of system performance, particularly as transportation agencies strive to embrace a more multimodal approach to transportation planning."
The report supports the use of accessibility as a standard performance measure.
h. Accessibility as an integrated transportation-land use measure. Trip- based mobility measures are the starting point for accessibility measures, but they are blind to trip purpose or opportunity; they just measure the performance of trips within a given time window. Accessibility measures layer on the trip purpose or type of destination represented by the trip and are meant to measure the ease of reaching opportunities – goods, services, activities and other destinations. Three factors affect accessibility: congestion (or impedance), transportation system connectivity, and land use patterns. Thus, accessibility measures capture all four of these simultaneously; it is still important to understand the contribution of components, especially mobility as this is under more direct control of transportation agencies and easier to communicate to a general audience for a greater range of purposes. Note the accessibility can apply to the ease of getting to activities (such as jobs, recreation, shopping) or aspects of the transportation system itself (freeways, transit route, bike facilities).
[The lead was Cambridge Systematics, with Dowling Associates and TTI, I was on the project team]