Any project that connects a new driveway, street, or intersection to a state highway in Colorado needs an access permit before that connection can be built. This is a separate approval from your local grading, site-plan, or subdivision permit, and it runs under state rules regardless of which city or county the project sits in. Miss this one on your entitlement schedule, and it typically shows up late — during civil plan review, when a reviewer flags that the site's frontage abuts a state route — which can cost real weeks if a traffic study wasn't scoped from the start.
When do I need a CDOT State Highway Access Permit?
You need an access permit whenever a project proposes a new access point, or a change to an existing access point, connecting to a state highway — a road under the jurisdiction of the Colorado Department of Transportation. This covers new driveways, new public street intersections, changes in access use or design (adding lanes, changing a right-in/right-out to full movement), and increases in the traffic generated by a site that materially changes how the existing access functions. If your site's only frontage is on a state highway, or a proposed public street ties into one, assume an access permit applies until you've confirmed otherwise with the issuing authority.
What is the State Highway Access Code?
The State Highway Access Code, codified at 2 CCR 601-1, is the regulation that governs all access to the state highway system. It sets the standards for access spacing, sight distance, turn-lane and taper design, permit categories, and the review criteria used to approve or deny an access request. Every access permit issued in Colorado — whether processed by CDOT directly or by a local government acting under delegated authority — is evaluated against this Code. If you're doing site-civil work anywhere in Colorado, the Access Code is worth having on hand the same way you'd keep a local drainage criteria manual.
Who issues my access permit — CDOT or the local jurisdiction?
This is the detail that trips up teams new to Colorado. CDOT delegates issuing authority for certain state highway access permits to some local governments that have executed an intergovernmental agreement with the department; for those roads and those jurisdictions, you apply to the city or county rather than to CDOT directly, and the local agency reviews and issues the permit under the same State Highway Access Code standards. Where no such delegation exists, or where the highway falls outside the scope of the local agreement, CDOT's regional office is the issuing authority. The practical rule: do not assume — confirm with the local jurisdiction's engineering department, early, whether they hold delegated access authority for the specific highway your project fronts. Getting this wrong means submitting to the wrong desk and losing calendar time.
What access categories does CDOT use?
The State Highway Access Code sorts state highways into access categories that reflect the highway's function and mobility priority — broadly ranging from limited-access, higher-mobility corridors where new access is tightly restricted, down to lower-category segments where more frequent access is permitted. The category assigned to your highway segment governs how much latitude you have to request a new or modified access point, what spacing standards apply relative to existing access points and intersections, and how much design flexibility a reviewer has. A parcel fronting a higher-category segment should expect a more restrictive review and a stronger push toward shared access, a frontage road, or access via a lower-category side street instead of a direct highway connection.
When does an access permit require a traffic study or auxiliary lanes?
Whether a traffic impact study, turn-lane analysis, or auxiliary lane (right-turn deceleration lane, left-turn lane, acceleration lane) is required depends on the trip generation of the proposed use, the access category of the highway, existing traffic volumes and speeds, and sight-distance conditions at the proposed location. Reviewers use these factors — not a flat trip-count threshold alone — to decide whether the access can be approved as a simple driveway or needs geometric improvements to the highway itself. Sites with higher-trip-generating uses (retail, multifamily, industrial with heavy truck movement) on higher-category highways should plan for a traffic study as a near-certainty, scoped early enough that its findings can inform the access design rather than force a redesign after submittal.
CDOT access permit process at a glance
| Step | What happens |
|---|---|
| Confirm issuing authority | Determine whether the local jurisdiction holds delegated authority for this highway, or whether CDOT's regional office reviews directly |
| Scope traffic analysis | Determine whether a traffic study or turn-lane/auxiliary-lane analysis is needed based on trip generation, access category, and site conditions |
| Prepare application | Access permit application plus supporting engineering — site plan, access design, sight-distance analysis, traffic study if required |
| Submit for review | To CDOT regional office or the delegated local agency, per the confirmed issuing authority |
| Address comments | Respond to design or capacity comments — geometry, spacing, auxiliary lane requirements |
| Permit issuance | Access permit issued with conditions; construction of the access improvements typically required before or concurrent with site occupancy |
How does the CDOT access permit fit into my overall project sequencing?
Access permitting sits alongside, not inside, your local site-plan or subdivision review — but the two are rarely independent in practice. Local jurisdictions frequently will not issue a final site-plan or building permit until the state access permit is approved, because the access design affects the site plan's driveway location, internal circulation, and sometimes the building setback if a turn lane or right-of-way dedication is required along the frontage. Treat the access permit as a long-lead item: confirm the issuing authority and scope the traffic analysis during conceptual design, not after your civil drawings are locked. For the ROW and encroachment work that often runs in parallel — utility crossings, drainage outfalls, or other work within highway right-of-way — see the ROW encroachment permit guide. For how access permitting fits into Colorado's broader site-civil permitting picture, start with the Colorado site-civil permitting guide.
What design elements does CDOT review most closely?
Beyond the threshold question of whether access is permitted at all, most of the substantive review effort on a CDOT access application goes into a handful of recurring geometric issues: access spacing relative to adjacent driveways and intersections, corner clearance, sight distance in both directions from the proposed access point, the turning radius and throat width needed for the site's design vehicle, and whether the access design forces or accommodates a specific turn movement (right-in/right-out versus full movement). On sites with existing access already in place — a redevelopment or infill parcel — expect additional scrutiny of whether the existing access configuration can be retained as-is or must be brought up to current Access Code standards as a condition of any modification, even a modest one like adding a second driveway or widening an existing curb cut.
What happens if I change my site plan after the access permit is issued?
An access permit is issued for a specific access location, design, and use. Material changes — a different building use with higher trip generation, a relocated driveway, added access points, or a change in the approved traffic movements — generally require an amendment or a new permit application, evaluated again against the State Highway Access Code. Don't treat an issued access permit as a fixed asset if the underlying site plan is still moving; confirm with the issuing authority whether a proposed change needs a permit modification before you build to a design that no longer matches what was approved.
The CDOT access permit is a small line item on most project schedules until it isn't — and on any parcel with state highway frontage, it deserves the same early attention as your grading and drainage permits. Confirm who issues it, scope the traffic analysis honestly, and sequence the access design alongside your site plan rather than behind it.