NOTE: TSI is updated monthly. The index numbers for the latest three months are considered to be preliminary. BTS releases the preliminary number for the latest month and replaces the number for the oldest preliminary month with a revised number. All other revisions are held until a bi-annual comprehensive revision of the TSI, which will be released as part of the July 2009 TSI release.
The Transportation Services Index (TSI), created by the U.S. Department of Transportation (DOT), Bureau of Transportation Statistics (BTS), measures the movement of freight and passengers. The index, which is seasonally adjusted, combines available data on freight traffic, as well as passenger travel, that have been weighted to yield a monthly measure of transportation services output.
