Colorado Traffic Impact Analysis (TIA)

The Colorado Department of Transportation (CDOT) reviews traffic studies whenever a proposed development creates a new access point, modifies an existing one, or changes the use of an access to a state highway. This review is governed by the State Highway Access Code (2 CCR 601-1) and is handled through the State Highway Access Permit process by the relevant CDOT Region office (Regions 1 through 5).

CDOT evaluates the access category of the highway, trip generation, turn-lane and acceleration/deceleration-lane warrants, auxiliary lane needs, sight distance, and the operational impact on the state highway. Depending on the access category and volume, CDOT may require a formal Traffic Impact Study prepared to Access Code standards. Gradient Systematics coordinates directly with CDOT Region access managers from the initial access permit application through issuance.

Colorado has no single statewide municipal threshold — each city and county sets its own within its land development or subdivision code. Most Front Range jurisdictions, however, use a tiered "assessment level" approach that scales the required study to the size of the project.

A common pattern is: a full Traffic Impact Study for developments generating roughly 100 or more added peak-hour trips, an abbreviated study or traffic memo for projects in the 20–100 peak-hour trip range, and a base assessment (or waiver) for very small projects below that range. Cities such as Denver, Colorado Springs, Fort Collins, and Aurora each publish their own thresholds and study-level definitions, so the trigger and required scope should always be confirmed against the specific jurisdiction's code.

Projects that access a state highway are additionally subject to CDOT's State Highway Access Code, which can require a study even when the municipal threshold is not met.

Yes. Traffic impact studies submitted to Colorado municipalities, counties, and CDOT must be prepared under the responsible charge of a Professional Engineer licensed in the State of Colorado. Licensure is administered by the Colorado State Board of Licensure for Architects, Professional Engineers and Professional Land Surveyors, part of the Department of Regulatory Agencies (DORA).

Many reviewing agencies also prefer a Professional Traffic Operations Engineer (PTOE) for studies involving signal warrant analysis, corridor operations, or complex access design. Gradient Systematics' engineers hold Colorado PE licensure and PTOE certification, ensuring every study meets the professional-qualification standard accepted by Colorado agencies and CDOT.

A State Highway Access Permit is required for any new access, modified access, or change in the use of an existing access to a Colorado state highway. CDOT issues these permits under the State Highway Access Code, which classifies each highway into an access category that governs spacing, allowable movements, and design.

A Traffic Impact Study is typically required as part of the permit when the development generates significant volumes, when the proposed access does not meet the spacing or design standards for its access category, or when the access affects an intersection or highway segment already operating near capacity. CDOT may also require a study for high-turnover uses — fuel stations, drive-throughs, and similar — even at modest volumes, because of their operational impact on the state highway.

In most cases, yes. A single Traffic Impact Study can be scoped to satisfy both the local development review and the CDOT State Highway Access Permit review. Gradient Systematics routinely prepares dual-jurisdiction studies that address both sets of requirements in one document.

The key is scoping correctly from the start. Municipal reviews typically emphasize site-adjacent intersections, internal circulation, and multimodal connectivity, while CDOT review focuses on access category compliance, turn-lane warrants, and state highway operations. By incorporating both scopes early, we avoid duplicate analysis and keep the local and CDOT review timelines running in parallel.

Largely, yes. Traffic Impact Analysis (TIA) and Traffic Impact Study (TIS) are used interchangeably across most Colorado development reviews, and CDOT documentation generally uses "Traffic Impact Study." Depending on project size, an agency may instead ask for a traffic assessment, traffic memorandum, or trip generation letter — the lighter tiers in a jurisdiction's assessment-level system.

Regardless of the label, the core deliverable is the same: a PE-sealed study evaluating trip generation, intersection and access operations, and recommended mitigations. Gradient Systematics prepares studies that meet the requirements whatever the local terminology.

Timelines depend on the reviewing agency and study complexity. Front Range municipal reviews generally take 2 to 6 weeks per cycle, with most jurisdictions allowing one to two rounds of comments before requiring a resubmittal.

CDOT access permit reviews can run longer — commonly 4 to 12 weeks depending on Region workload, the access category involved, and whether the study requires turn-lane design, signal warrant analysis, or coordination with programmed CDOT projects. When both municipal and CDOT review apply, they are run concurrently where possible, but the overall schedule is usually governed by whichever review takes longer.

We use industry-standard traffic engineering tools matched to each project's requirements. Synchro and SimTraffic handle intersection capacity, signal timing, and microsimulation for most municipal and CDOT reviews. VISSIM and TransModeler are used for corridor-level or network-wide microsimulation, and HCS (Highway Capacity Software) covers freeway segment, ramp, and interchange analysis consistent with HCM methodology.

Every model is calibrated to Colorado conditions — local signal timing, CDOT traffic counts, seasonal and mountain-corridor adjustment factors where relevant, and heavy-vehicle percentages appropriate to the corridor. This ensures results reflect actual operating conditions rather than generic defaults, which is critical for clearing agency review on the first submittal.

To provide an accurate scope and timeline, we typically need: a site plan or concept plan showing the proposed layout, the land use type and size (square footage, unit count, or pad count), the number and location of proposed access points, and the jurisdiction where the project is located. If the site touches a state highway, note the highway number so we can identify the CDOT Region and access category.

If you have a submittal deadline, case or permit number, or any comments already received from city, county, or CDOT staff, send those as well — they help us identify review requirements early. You can submit this information through the form below, and we'll respond with a scoping outline and fee estimate.