Traffic Analysis Data Age and Relevant Changes Traffic Updates Cause to Project Design

Focus Area

NEPA Process


Environmental Process






1-2 years

Research Idea Scope

In NEPA analysis that goes on for numerous years for transportation projects, the traffic data is updated with analytical consequences periodically throughout the process. But how often do these expensive updates really change the project or mitigation design? How old is too old for traffic data on a transportation project? There are many examples of multi-year NEPA analysis throughout the US with periodic traffic updates. The proposed research is to look at a handful of completed NEPA projects and the traffic data that was updated over the years and see if the project design or mitigations really changed due to new traffic numbers, or if the original traffic analysis really did result in the same finding or conclusion. The idea is to build a case for keeping relevant the older traffic analysis though out the NEPA process unless certain triggers are met that would require reanalysis, but not just because of the age of the data.

Urgency and Payoff

Re analysis of traffic data is a very expensive process. The model runs are labor intensive, and this reanalysis trickles into air quality and noise analysis at a minimum which also need to be rerun. There can also be vibration issues, depending on the project. These additional model runs and analysis also delay the NEPA process. In the days of getting more for our money and shortening the NEPA process, there could be a tremendous time and cost savings found by figuring out the actual value of keeping the traffic data updated as often as we currently do.

Suggested By

Jane Hann Colorado DOT 3037579630

[email protected]