Nobody budgets for the third resubmittal. A traffic engineer review is where a lot of schedules quietly slip, and it rarely slips because the numbers were wrong. It slips because the assumptions were never agreed on before the work started. Fix that one habit and you cut weeks off your approval.
What a traffic engineer review actually is
Your project generates trips. The agency wants to know how many, where they go and what breaks. A traffic engineer builds that case in a study, and a reviewer on the public side checks it. Both sides use the same manuals, so the fight is almost never about math.
The review is a negotiation dressed up as a technical document. Every input is a choice someone made. Reviewers know that, which is why they push on inputs first.
Two engineers, two jobs
Your consultant works for you. They collect counts, run the analysis and write the report. They also tell you when your plan won’t survive review, and a good one says it early enough to matter.
The agency reviewer works for the public. Their job is to check the assumptions, not to help you pass. Some agencies hire an outside firm to do this as a peer review, and you often pay for that through a fee.
Treat the reviewer as a source, not an obstacle. They know what the last six projects on that road were told. That knowledge is free if you ask for it.
The scoping meeting decides your outcome
Scoping is the meeting where you and the agency agree on what the study will cover before anyone counts a car. Skip it and you’re gambling. Agencies that offer scoping almost always accept the results faster.
Bring a sketch plan, a land use, a unit count and a target opening year. Leave with something in writing. An email summary counts, and it will save you later when staff changes.
Agree on the study area
The study area is the list of intersections your report has to analyze. Three intersections and twelve intersections are very different bills. Agencies pick the list based on how many of your trips land at each one.
Push back if the list feels padded. Ask what threshold they used. A reasonable reviewer will tell you, and an unreasonable one will at least have to say it out loud.
Agree on the assumptions
Trip generation rates come from the ITE Trip Generation Manual, and most agencies require it. The arguments start with what you subtract from that number. Pass-by trips, internal capture and transit reductions all shrink your count, and reviewers watch those closely.
Get the reductions approved at scoping or expect them stripped later. Same with your background growth rate. Same with the list of nearby approved projects you have to include as future traffic.
What happens after you submit
The reviewer reads the report and sends comments. First-round comments are normal, even on good work. Most projects go two rounds, and three is common when scoping was skipped.
Comments come in three flavors. Some are clarifications you answer in a sentence. Some are recalculations that take a week. A few are real disagreements that need a meeting.
Answer every comment in writing, one by one, in a response matrix. Don’t bundle them. Reviewers hate hunting for answers, and a slow reviewer is your problem now.
Why resubmittals happen
The plan changed after the study started. That’s the number one cause, and it’s self-inflicted. Every unit count change ripples through the whole analysis.
Old counts are second. Many agencies won’t accept traffic counts older than a year or two, and some reject anything collected during a school break. Ask about count rules before you spend money on them.
The rest is usually an assumption nobody blessed. See the scoping section again.
The mitigation conversation
Mitigation is what you build or pay for because of your traffic. The study identifies it, and the agency decides what sticks. Your leverage is highest before the study is final and drops to near zero after approval.
Ask two questions early. Is this improvement already planned by the agency? Is another nearby project already required to build it? A yes to either one changes the conversation from paying alone to sharing.
Phasing is the underused move here. If your traffic arrives in year five, argue for a trigger tied to units built, not a certificate at day one. Reviewers accept this more often than developers ask for it.
Timeline reality
Counts take days to collect and can’t happen on a holiday week. The study takes weeks to write. Review takes whatever the queue takes, and multiple rounds stack.
Ask the agency for their current review turnaround in writing. Then add a round to whatever they say. Building your pro forma on a single clean review is optimism, not planning.
What to settle before you hire anyone
- What’s the agency’s study threshold, and does your project cross it?
- Does the agency offer a scoping meeting, and who attends?
- Which intersections are in the study area, and why those?
- Are your trip reductions approved in writing?
- How old can traffic counts be, and when can they be collected?
- What nearby approved projects go into the future volumes?
- Who pays for peer review, and how much?
Run that list before the contract is signed. Every item on it is cheap to answer now. Each one is a resubmittal later.
Frequently Asked Questions
What does a traffic engineer do for a development project?
They estimate the trips your project will generate, analyze how those trips affect nearby intersections, and write the study the agency reviews. They also recommend improvements and defend their assumptions during comment rounds. On the public side, an agency traffic engineer independently checks that work.
How long does a traffic study review take?
Study preparation usually takes several weeks after traffic counts are collected. Agency review time varies by jurisdiction and workload, and two comment rounds are common. Ask the reviewing agency for current turnaround times before setting your project schedule, then allow extra time for at least one additional review cycle.
What is a scoping meeting?
A scoping meeting is where you and the reviewing agency agree on the study area, trip generation assumptions, growth rates, and analysis years before the study begins. The agreed scope should be documented in writing. Proper scoping helps reduce review comments and minimizes the need for resubmittals.
Can I use my own traffic engineer?
Yes. In most cases, you should hire your own traffic engineer. The reviewing agency evaluates the study but typically does not prepare it. Some jurisdictions require the consultant to be licensed in the state and may maintain a list of firms familiar with local requirements. Be sure to ask whether a peer review fee applies.
Why did my traffic study get rejected?
Common reasons include unapproved trip reduction assumptions, outdated or improperly collected traffic counts, an incomplete study area that omits required intersections, or changes to the site plan after the analysis was completed. Many of these issues can be avoided through a thorough scoping process before the study begins.
