By Mike Spack, PE, PTOE
Part 1 in this series on scoping a traffic study dealt with the appropriate study area. This post (Part 2) discusses how far into the future we need to analyze.
The Institute of Transportation Engineers (aka ITE) has developed a Recommended Practice titled Transportation Impact Analyses for Site Development. It details the study year scenarios appropriate for different size developments. The following list presents ITE’s guidelines. You can use this as a starting point to make sure your traffic study is looking far enough into the future to identify the appropriate mitigation measures for your development.
Small Development (less than 500 peak hour trips)
- Anticipated opening year, assuming full build-out and occupancy
Moderate Single Phase Development (500 – 1,000 peak
hour trips)
- Anticipated opening year, assuming full build-out and occupancy
- 5 years after opening date
Large Single Phase Development (more than 1,000
peak hour trips)
- Anticipated opening year, assuming full build-out and occupancy
- 5 years after full build-out and occupancy
- Adopted transportation plan horizon year, if the development is significantly larger than that included in the adopted plan or travel forecasts for the area
 Moderate or Large Multiple Phase Development
- Anticipated opening years of each major phase, assuming full build-out
and occupancy of each phase - Anticipated year of complete build-out and occupancy
- Adopted transportation plan horizon year, if the development is
significantly larger than that included in the adopted plan or travel forecasts
for the area - 5 years after opening date if completed by then and there is no significant increase (less than 15 percent) in trip generation from adopted plan or area transportation forecasts
Please note this is a starting point for scoping out a traffic impact study. Coordinate with the jurisdictions involved in reviewing your traffic study as there may be local standards that are different than ITE’s guidelines.
As one of my projects in my transportation engineering design course, I have to analyze the different alternatives for a weaving section of a highway. My group did not consider the developments near this section, but as a traffic engineer, it is important to take in the consideration of developments. These developments can have a major impact on both the alternatives to the weaving section and the surrounding residential area. These type of things can easily be a factor in determining the best solution and whether the project will be improved. As traffic engineers we need to consider every situation and development around the area. But as you said, there is a limit on how far the development has an impact on the surrounding areas.
Mike,
I live in a gated community in California. We’d like to put in several stop signs in the neighborhood to discourage speeding. Since the streets within the gate are considered private property, would a traffic study be necessary?