"It depends" is the honest answer every developer, engineer, and city reviewer eventually hears when they ask this question — and it's genuinely accurate. Texas has no single statewide TIA law. Whether your project needs one comes down to your city, your county, and sometimes TxDOT, each with its own thresholds and review process.
At Gradient Systematics, we walk clients through this every week. Here's the technical breakdown, translated for anyone involved in getting a project approved — not just traffic engineers.
The Core Trigger: Peak-Hour Trips
Most Texas jurisdictions size a TIA requirement around peak-hour trips, calculated using the ITE Trip Generation Manual — the industry standard for estimating how much traffic a given land use will produce. In plain terms: bigger, busier uses need more traffic vetting.
Across most of DFW, a TIA is typically required once a project generates 100 to 200 peak-hour trips. In practical terms, that roughly translates to:
Approximate thresholds by land use
- Single-family residential ~150+ units
- Multifamily ~220+ units
- Shopping center ~15,000+ sq ft
- General office ~45,000–55,000+ sq ft
- Industrial / warehouse ~70,000+ sq ft
Below these numbers, many cities still require a shorter traffic memo instead of a full study — so "no TIA" doesn't always mean "no traffic documentation."
It's Not Just About Size
A few other triggers matter just as much as square footage:
Rezoning & occupancy changes
Changes that meaningfully increase trip generation can trigger a study even without new construction.
New driveways & access points
New access on arterial roads — or anywhere a state highway is involved — pulls TxDOT into the review alongside the city.
Poor Level of Service (LOS)
Nearby intersections already at a failing grade on the A-through-F LOS scale can flag even a smaller project.
Phased developments
Reviewers look at cumulative impact across every phase — not just the one you're submitting first.
Why DFW Specifically Gets Complicated
DFW isn't one jurisdiction — it's dozens. Dallas, Fort Worth, Plano, Frisco, McKinney, Arlington, and Richardson each run their own review process, and fast-growing suburbs are still updating their codes as they grow. A project that needs nothing in one city might need a full study a few miles away. And if your access point touches a TxDOT-maintained road, that's a separate, parallel review — not a substitute for the municipal one.
This is exactly the terrain our Texas TIA team works in daily. We maintain direct relationships with reviewers across the Dallas and Fort Worth TxDOT districts and DFW municipal staff, so we know the applicable threshold before you're deep into site design — not after a rejected submittal.
What a Study Actually Involves
Once a TIA is required, expect:
- A scoping meeting to agree on study intersections and methodology
- Trip generation and distribution
- Intersection capacity analysis (typically in Synchro)
- Background growth and horizon-year projections
- Mitigation recommendations, if needed
In Texas, every TIA must be sealed by a licensed Professional Engineer, and many agencies also want a PTOE (Professional Traffic Operations Engineer) on the study. Our standard delivery timeline runs about six weeks from scoping to a reviewer-ready report, and we stay engaged through every round of agency comments until final approval.
The Takeaway
Don't assume last project's threshold applies to this one, and don't wait until site plan submittal to ask the question. A short scoping conversation up front — often free — can save weeks of redesign later.
Want to go deeper?
Check out our guide on what a traffic impact analysis actually is — a plain-English breakdown of what a study includes, who reviews it, and how the process works.