Texas A&M Transportation Institute
以下でアクセス： 21 9月, 2017
Findings in the 2015 Urban Mobility Scorecard are drawn from traffic speed data collected by INRIX on 1.3 million miles of urban streets and highways, along with highway performance data from the Federal Highway Administration. The 2015 edition provides a comprehensive analysis of traffic conditions in 471 urban areas across the United States. The vast amount of information makes it possible to examine problems in greater detail than before, and to identify the effect of solutions at specific locations.
Travel time index: The ratio of the travel time during the peak period to the time required to make the same trip at free-flow speeds. A value of 1.30, for example, indicates a 20-minute free-flow trip requires 26 minutes during the peak period (20 minutes × 1.30 = 26 minutes)
The Commuter Stress Index is the same as the Travel Time Index but is based only on peak direction travel only.