The induced travel effect of highway expansion needs to be accounted for in the model when projecting future emissions. The Long Range Plan and TIP contain major highway expansion projects. Induced travel is defined as the increase in VMT that can be attributed to expansion of highway capacity, and is connected with land use changes resulting from the new capacity. The failure to represent land use changes resulting from new highway capacity is likely to result in an underestimation of auto trips. Projection of future emissions should not be done until the UrbanSim land use model is completed or until a Delphi review, as recommended by the peer review panel as an immediate model improvement, is undertaken.
Research continues to provides more and more evidence for the the induced travel effect.
A Review of Recent Literature with a Discussion of Policy Issues. EPA, Office of Policy, Energy and Transportation Sectors Division, 2000. The possible use of Mobile6 during the timeframe of the development of the PM10 SIP is an important issue. At the time of availability and consideration of use of Mobile6, there should be an updated detailed protocol with opportunity for public comment. Mobile6 should not be used for conformity determination with a budget determined by use of Mobile5b.