Next time you attend a public workshop on a proposed road or street project, ask the project engineer how the traffic forecasts were prepared. The answer will usually be that forecasts of local traffic growth (based on land use forecasts) were added to a “background” or “regional” traffic growth factor. Ask what that that background growth factor is and the answer most often will be 2 – 3% per year.
How reasonable is that? Let’s take a look.
While overall VMT nationwide has declined by 2% since 2006, the decline has not yet cancelled out the growth that occurred during the first six years. So the twelve-year trend was a net 8% – about 0.67% annually. At the state level in the Rocky Mountain West, states experienced growth in total VMT from 2000 to 2012, while Colorado and Wyoming saw declines during the last six years of that period. The decline nationally since 2006 has been widely reported by the media. However, highway advocates counter that this decline was due to temporary factors associated with the Great Recession coupled with rising fuel costs and should not be viewed as a long term trend.
But there is more to the story.
