TxDOT Driveway Spacing

January 22, 2018 by Shaun Theriot-Smith

If you are developing a property on a roadway that is controlled by the Texas Department of Transportation (TxDOT) and want to maximize access, you will have to consider TxDOT standards on driveway spacing. This is one of the criteria that TxDOT will assess your access driveway permit application.

Why does driveway spacing matter?

Photo by Irina Blok on Unsplash

We often are taught to keep a “two second distance” between ourselves and the car in front of us. The intention is that we will have the distance and time to react should they behave unexpectedly. But this is an overgeneralization, since a driver’s reaction time and their appropriate stopping distance varies not just with the speed which you and the rest of traffic are going, but also physical factors such as the effectiveness of your vehicle’s brakes, incline or the road, traction, and other conditions.

Traffic and transportation engineering takes many variables and produces a design that keeps you and I safe on the road. These design principles become design criteria much like TxDOT’s access road and driveway spacing requirements.

What are the driveway spacing requirements?

The distance between driveways are measured from the edges of pavement of the driveway, prior to the return radius.

TxDOT driveway spacing diagram

How far your access roads and driveways will need to be designed varies directly with the type of road your development lies on and the posted speed (this varies from a roadway design speed, which can often be higher than the speed limit). Let’s break it down by road type:

Freeway Mainlanes

  • Access to properties along Freeways are generally not allowed from mainlanes and require an interchange or entrance and exit ramps to frontage roads which then provide access to properties.

Freeway Frontage Roads

  • Frontage roads typically are aligned parallel to freeway main lanes and connect properties from freeway interchanges and arterial roads that tie-in to the frontage.

Frontage Roads TxDOT Driveway Spacing

Other State Highways

  • State system highways that are not freeways or rural highways with Annual Average Daily Traffic (ADT) volumes below 2000 (which require more traffic analysis for permitting).

Other state highways TxDOT minimum driveway spacing table

Exceptions and Variances

These distances assume the highway approach to the driveway is on level grade. If there is a downslope or upslope present, the permitting team my require a greater or lower spacing distance.

TxDOT further divides its jurisdiction into districts, that are given authority to amend these rules as needed for their regions. The department also enters into agreements with some municipalities to create special access standards that are more appropriate to their local communities.

If your development cannot meet these minimum requirements, then a variance may be required. The variance process is initiated during the driveway application process and is approved by the TxDOT permitting team. A variance often comes with special performance or design criteria for the driveway and development in question. Emergency access driveways and field driveways are also permitted on a case by case basis.

There are two automatic exceptions from spacing requirements:

  • If a TxDOT construction or improvement activity causes a property to otherwise become “land-locked”. This exception does not apply to properties that have become land-locked due to a subdivision and will often require properties to share access to existing driveways or shared access drives.
  • Existing driveways that are rendered inaccessible due to highway construction.

If you are developing a property and need assistance securing an approved permit for an access driveway on a TxDOT Right of Way, our traffic and site development permitting experts can prepare and expedite your permitting process. Contact BIG RED DOG Engineering at 1-877-733-3642 or click here to send us a message.

This article originally appeared on Shaun Theriot-Smith’s blog, Building Bayou City.

Written by Shaun Theriot-Smith

Shaun Theriot-Smith

Shaun Theriot-Smith is a Project Engineer in our Houston office. Shaun graduated from The University of Houston with a Bachelor of Science in Civil Engineering. He enjoys spending time with his wife and twin daughters.