Jump to main content.


  Development Work for Improved Heavy-Duty Vehicle Modeling Capability Data Mining – FHWA Datasets (138 pp, 7.49 MB) (EPA/600/R-07/096) July 2007

Development Work for Improved Heavy-Duty Vehicle Modeling Capability Data Mining - FHWA Datasets

Heavy-duty vehicles have been seen as contributing a large fraction of emissions from on-road vehicles. They are coming under more intense scrutiny because light-duty vehicle emissions have been controlled to a greater extent than heavy-duty vehicle emissions. A heavy-duty vehicle can produce 10 to 100 times the emissions (nitrogen oxide and particulate matter especially) of a light-duty vehicle.

Key uncertainties with the use of the current model, MOBILE6, regarding heavy-duty vehicle emissions include the fraction of heavy-duty vehicles on all types of roadways at all times of day. In addition, there may be regional variability in both the fraction of different vehicle classes and the vehicle weights within each class.

With the Motor Vehicle Emissions Simulator model, greater emphasis is given to physical parameters affecting the engine loads and, therefore, the emissions from individual vehicles. One primary factor affecting the engine load is the vehicle weight; the weight of the vehicle on the road is needed to estimate its in-use emissions. Because the effect of vehicle weight may be nonlinear for certain types of driving, it is important to incorporate the weight distribution of vehicles into emission estimates.

Databases collected by the Federal Highway Administration (FHWA) include vehicle count and classification from the Highway Performance Monitoring System using automated traffic recorders used to produce the Travel Volume Trends reports. Other data sets compile the results from weigh-in-motion sensors and other data sources, such as visual observation and weigh stations maintained by the FHWA and compiled in the Vehicle Travel Information System. A discussion of these data sources, including original sources, representativeness, quality, and data reduction procedures used in this work, are provided.

This work consisted of an investigation and evaluation of these databases in order to assist in developing improved emissions estimates of heavy-duty vehicles. The goals of the project were to:

  • Produce estimates of the fraction of heavy-duty vehicles of all vehicle traffic
  • Weight distributions for those vehicles according to the time of day, day of week, and other temporal variables
  • Investigate regional differences


Sue Kimbrough

You will need Adobe Reader to view some of the files on this page.
See EPA's PDF page to learn more.

Local Navigation

Jump to main content.