When time permits (assuming no one week deadlines), I find the most efficient way to work through the traffic study approval process is to start by sending the reviewing agencies the scope and assumptions that will serve as the foundation of your traffic impact study.
The review process usually (but not always if you have a flip-flopper at the agency) goes faster if you agree on the foundational aspects of the traffic study at the beginning stage versus revising your study later based on the review letter you'll get back from the agency. This allows the reviewing agency to focus their review letter on the conclusions and recommendations instead of the nuts and bolts of the forecasts and capacity analyses.
If the agency will have a traffic engineering consultant review your study, make sure they're included in the discussion about the scope/assumptions. You want to get confirmation from the actual people who will be commenting on the study, not their bosses boss.
I like to start with an email. Often a few emails are enough to agree on the details. But I've run into a few agency folks who prefer to iron out the details in a meeting. As a starting point, here are topics I recommend you cover in your email:
- Give an overview of the proposed development
- Brief description of the development
- A location map
- A concept plan (highlight the proposed access points)
- Anticipated build-out year
- Phasing plan if the development will be built in stages
- Detail the size of the development (i.e. square footage, dwelling units, etc.)
- Provide the preliminary framework of your study
- A map with the intersections and corridors you propose to study.
- A map showing the distribution pattern the site’s traffic will use.
- A table giving the traffic generation of the proposed development. Mark it preliminary.
- List the study periods you plan to study (daily, a.m. peak hour, p.m. peak hour, and/or Saturday midday peak hour).
- List your proposed analysis years.
- Document how you will increase the existing traffic counts to your future no-build scenario traffic counts.
- List the methodology/software you’ll use for your analyses.
- Request traffic signal timing plans if they have control over the traffic signals at any of your study intersections.
- Ask about (or confirm) proposed development and roadway projects planned within the study area.
- Ask if they have policies, ordinances (especially traffic impact fees), and/or standards related to traffic studies. If you found references online, confirm you have the current information.
- Provide your schedule and ask about their typical review process and its associated timeline (i.e. how much time will they need to review your traffic study).