About

The number of vehicle miles of travel (VMT) is an indicator of the travel levels on the roadway system by motor vehicles. VMT is estimated for the given time period. This estimate is based upon traffic volume counts and roadway length. As Florida’s population continues to grow, VMT has grown at a rate higher than the national rate. However, the growth in population is not the only factor fueling the rise in travel. Other factors include economic growth, relatively affordable auto travel costs, tourism, low levels of public transit, sprawl, and related factors. As the amount of auto travel increases, the time wasted on congested roadways, the energy used by the vehicles and total costs of auto travel increase accordingly.

For the monthly VMT's, the statistical data on vehicle miles of travel are taken from the Federal Highway Administration’s monthly Traffic Volume Trends report. The annual VMT data is taken from the Federal Highway Administration's Highway Statistics Series. The Federal Highway Administration receives monthly Automatic Traffic Recorder (ATR) reports from states on a voluntary basis. These data are processed by Traffic Volume Trends software and applied to the annual VMT data provided by the State for all public roads, to calculate the monthly state VMT and the percent change. The monthly vehicle miles of travel for states that do not submit the ATR are estimated using surrounding states data or the national average. Florida did not participate in this program in 2002, because of software difficulties and upgrades. The monthly VMT from this source was an estimated value of changes in VMT based on the previous years’s VMT and changes in average daily traffic counts. Monthly VMT is difficult to estimate for most of Florida’s public roads, because the 300 ATRs are positioned on the State Highway System. It is also interesting to note the strong seasonality of the vehicle miles of travel trend.

The Florida Department of Transportation's Transportation Statistics Office collects volume data at permanent and temporary traffic count stations throughout the state. This data is used to determine traffic statistics including Annual Average Daily Traffic (AADT). Traffic adjustment factors from the ATRs are used to adjust the coverage counts. Highway usage trends are also important in managing congestion on Florida’s roadways and measuring mobility performance. To learn more on these topics visit http://www.dot.state.fl.us/planning/statistics/.