The short answer
Inside the City of Austin, a development needs a traffic study once it generates more than 2,000 net new unadjusted daily trips. Between 2,000 and 4,999 daily trips it is a Transportation Assessment; at 5,000 or more it is a full Transportation Impact Analysis. A Transportation Demand Management plan is required at 2,000 and above. Outside city limits, none of that applies — the suburbs and counties use their own thresholds.
Austin's requirements go further than most Texas cities, and they are structured differently in a way that catches out teams working from experience elsewhere in the state. Most Texas jurisdictions size a traffic study requirement around peak-hour trips. Austin uses daily trips. A project that would fall below a peak-hour threshold in Houston or Dallas can land squarely inside Austin's requirement.
On top of that, Austin layers two things most Texas cities do not have: a mandatory Transportation Demand Management plan, and a Street Impact Fee that changed what a study is actually for. This page covers each of them, and the question that causes the most confusion — which agency is going to review the report.
When the City of Austin Requires a Traffic Study
The requirement lives in Section 10 of the Transportation Criteria Manual (TCM), in the version that took effect June 20, 2022. It scales in tiers based on net new unadjusted daily vehicle trips:
| Net new daily trips | What is required |
|---|---|
| Under 2,000 | Trip-generation determination No traffic study is required. A trip-generation determination documents the estimate that puts the project below the threshold. |
| 2,000 – 4,999 | Transportation Assessment (TA) The lighter of the two study tiers. A TDM plan is also required at this level. |
| 5,000 or more | Full Transportation Impact Analysis (TIA) The complete study, including capacity, access, queueing, and multimodal analysis. A TDM plan is required. |
A separate track: Neighborhood Traffic Analysis
Independently of the tiers above, a Neighborhood Traffic Analysis may be required where a project takes access to residential streets and generates 300 or more net new daily trips, and for public primary and secondary schools. Because this threshold sits well below the 2,000-trip study trigger, a project can be exempt from a TIA and still owe a neighborhood analysis.
Because the tiers are set by trip generation rather than by land area or unit count, the trip-generation estimate is the decision that determines everything downstream — which tier applies, how much analysis is needed, and what the study will cost. It is worth settling that number before scoping anything else.
How the Process Starts: the Determination Worksheet
Austin front-loads the tier decision. Applicants submit a TIA Determination Worksheet through the Transportation Development Services Division's TIA Portal before zoning or site plan submittal — not alongside it. The worksheet is what establishes whether a study is required at all and, if so, which tier applies.
Sequencing matters here. Because the determination precedes the zoning or site plan application, a trip-generation assumption that turns out to be wrong does not just change the study scope — it can invalidate the submittal path a project has already started down. This is the single most common avoidable delay in the Austin process.
It is also worth knowing what the City expects the scope to contain, because Austin is not purely a capacity-analysis jurisdiction. Beyond intersection capacity, a scope commonly includes TDM measures, sustainable modes, access management, queueing analysis for schools and drive-throughs, and Street Impact Fee offset calculations.
The Street Impact Fee and What It Replaced
Austin's Street Impact Fee (SIF) was adopted in 2020 and has been assessed on development since 2022. It is a one-time charge based on a project's intensity and land use, and it funds roadway-capacity improvements across the city.
The part that matters for a traffic study is procedural: the "SIF Max" calculation replaced the older rough-proportionality method for determining a development's share of roadway costs. In practice the fee now covers much of the network-capacity mitigation that a study previously assigned to the developer directly, while the study itself still identifies the site-specific improvements needed for safe and efficient access — turn lanes, driveways, signals.
The practical consequence is that the study and the fee need to be scoped against each other. Where they are not, it is possible to be charged twice for the same impact: once through the fee, and again through a mitigation commitment in the study.
TDM Plans and Multimodal Analysis
A Transportation Demand Management (TDM) plan is required for all developments generating 2,000 or more daily trips — the same threshold that triggers the study itself. TDM measures such as transit access, bicycle facilities, and parking management can earn vehicle-trip reductions, which in turn lower the analytical burden of the study.
This reflects the Austin Strategic Mobility Plan (ASMP) and its 50/50 mode-share goal. The City expects a study to consider pedestrian, bicycle, and transit access alongside vehicular capacity — not level of service alone. A report scoped as a conventional vehicular capacity analysis will come back with comments.
Who Reviews Your Study
This is the question that most often goes wrong, because the answer depends on two things at once: where the site sits, and which roadway it takes access from. Five different reviewers are possible in the Austin region, and a site near a jurisdictional or corridor boundary can trigger several of them simultaneously.
| Reviewer | Applies to | Basis |
|---|---|---|
| City of Austin — Transportation Development Services | Inside city limits and Austin's extraterritorial jurisdiction (ETJ) | Transportation Criteria Manual §10 — net new daily trips |
| Travis, Williamson, and Hays Counties | Unincorporated areas of each county | County development standards |
| Suburban municipalities | Round Rock, Cedar Park, Georgetown, Leander, Kyle, Buda, San Marcos, and others | Each city's own ordinance — frequently peak-hour trips, not daily |
| TxDOT Austin District | New or modified access to any state-maintained roadway | State Highway Access Permit review |
| Central Texas Regional Mobility Authority (CTRMA) | Sites fronting CTRMA-operated tollways | Tollway coordination, in addition to the local and TxDOT reviews |
Note the second and third rows: the Street Impact Fee and the TDM requirement are City of Austin instruments. They do not extend into the suburbs automatically. Projects on the metro fringe — particularly the fast-growing corridors in Williamson and Hays Counties — frequently sit under a suburban city's review, a county's review, and TxDOT's review at the same time, under three different rulebooks, none of which is the TCM.
Which Rulebook Applies Outside Austin
Each surrounding jurisdiction maintains its own traffic-study requirements in its own document. Knowing which document governs is the first step; the thresholds inside them vary and frequently key off peak-hour trips rather than Austin's daily-trip model.
| Jurisdiction | Governing document |
|---|---|
| Round Rock | Its own Transportation Criteria Manual, with a separate TIA section |
| Cedar Park | TIA ordinances adopted February 2021 |
| Pflugerville | TIA requirements set out in its Engineering Design Manual |
| Georgetown | TIAs addressed in its Unified Development Code |
| Travis County | County TIA guidelines published May 2020 (unincorporated areas) |
Leander, Kyle, Buda, San Marcos, Taylor, and the unincorporated areas of Williamson and Hays Counties each run their own review as well. Confirm the current threshold directly with the reviewing jurisdiction before assuming a project falls below it.
Corridors That Bring in TxDOT or the CTRMA
Any new or modified access to a state-maintained roadway requires a State Highway Access Permit from the TxDOT Austin District. The corridors that most commonly pull TxDOT into an Austin-area project are I-35, MoPac (Loop 1), US-183 and the Bergstrom Expressway, US-290, SH-71, SH-130, RM 620, and RM 2222.
Several of the region's major routes are tolled and operated by the Central Texas Regional Mobility Authority — 183A, the 290 Toll, the MoPac Express Lanes, and SH 45SW. A site fronting one of those adds a second layer of coordination on top of the local and TxDOT reviews. Access permit scoping, driveway spacing, sight distance, and turn-lane warrants all get evaluated at this level.
How the Metro Breaks Down
"Austin" in a development context usually means one of three counties, and which one you are in changes the governing standard entirely.
Travis County — Austin, Pflugerville, Del Valle
The urban core and its densest development, plus the Tesla Gigafactory near Del Valle. This is where Austin's full framework applies — the Transportation Criteria Manual, mandatory TDM plans, and the Street Impact Fee — with congestion on I-35 and MoPac shaping nearly every study.
Williamson County — Round Rock, Cedar Park, Georgetown, Leander, Taylor
One of the fastest-growing counties in the nation, anchored by Samsung's Taylor semiconductor campus and sustained growth along the 183A tollway and I-35. Each city runs its own review, distinct from Austin's daily-trip model.
Hays County — Kyle, Buda, San Marcos
Rapid southern-metro expansion along the I-35 corridor between Austin and San Antonio. Kyle and Buda are among the fastest-growing suburbs in Texas, while San Marcos adds university and outlet-retail traffic patterns that require careful trip-generation assumptions.
What to Expect from Review Timelines
Timelines depend on the reviewing agency and the study tier, so treat the following as planning guidance rather than commitments. City of Austin Transportation Development Services reviews typically run several weeks per cycle. Because Austin studies carry TDM and multimodal components, the first review often returns more comments than a conventional vehicular-only study would — budgeting for one or two comment rounds is prudent.
County reviews in Travis, Williamson, and Hays are broadly comparable. TxDOT Austin District reviews for State Highway Access Permits generally take longer, particularly where turn-lane design or signal warrant analysis is involved. Where a project needs both local and TxDOT approval, the two reviews can usually be run concurrently, in which case the schedule is governed by whichever review takes longest rather than by their sum.
Where These Rules Come From
Requirements change. Before relying on any threshold on this page, confirm it against the source:
- City of Austin Transportation Criteria Manual — Section 10 sets the study tiers and thresholds
- City of Austin Street Impact Fee — fee schedule, applicability, and the SIF Max calculation
- Austin Strategic Mobility Plan — the mode-share policy behind the multimodal expectations
For suburban cities and unincorporated county sites, the governing document is the individual city ordinance or county development standard, not any of the above. Those thresholds vary and should be confirmed with the reviewing jurisdiction directly.