By Mike Spack, PE, PTOE
I’m occasionally hired to review traffic studies other consultants have prepared. Here’s a list of questions I use when I have to go through a traffic study:
- Project Description Review. Does the traffic study have a complete project description?
- Type of proposed uses
- Size – building square footages, units, etc.
- Build in phases? When is full occupancy expected?
- Proposed site plan
- Study Years. Do the study horizon years make sense?
- Study Hours. Are the study hours reasonable?
- Other Intersections. Are all possibly impacted intersections studied?
- Trip Generation Data. Is the trip generation data reasonable? Is new or specialized trip generation data needed for the study?
- Trip Distribution Pattern. Does the trip distribution pattern seem reasonable (this is the most subjective part of any traffic study – pay special attention)?
- Analysis Methods. Do the analysis methods seem reasonable (micro-simulation if closely spaced intersections or queuing issues)?
- Forecasting Method. Is the method for forecasting future years reasonable (typically based on a growth rate assumption)?
- Other Developments. Are there other nearby developments that should be accounted for in traffic forecasts?
- Forecast Data. Do the forecasts make sense (peak hour volumes going between intersections balance, are the trips from the site distributed per distribution pattern, daily forecasts are +/- 10 times peak hour volumes, etc.)?
- Data Accuracy. Is the technical data in the appendices accurate? Make sure the peak hour factor used in Level of Service analysis is reasonable. Spot check to make sure the turning movement volumes are correct and signal timing plans are reasonable in Level of Service analysis.
- Warrant Analysis. If an upgrade in traffic control is recommended, is a warrant analysis included per MUTCD?
- Access Points. Do proposed access points meet agency access spacing guidelines? If not, full justification is needed for a variance.
- Right of Way Considerations. Is sufficient right-of-way being dedicated to provide for long term traffic control and roadway geometry that may be needed?
- Improvement Funding. If improvements are needed, who’s paying?
- Recommendation Review. Do the recommendations make sense (is there a better solution or are superficial improvements being recommended)?
- Visit the Site. The last thing I do….I go to the site to make sure I didn’t miss anything.
I have created a Traffic Study Manual that is will help you create thorough and thoughtful traffic studies every time. Also, get a free copy of our Trip Generation data with more than 10,000 hours of professionally collected trip generation data at TripGeneration.org.
What considerations do you look at when you review a traffic study? Share your comments below.