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San Antonio Area Freeway System
PROJECT INFO: I-10 from La Cantera to Ralph Fair

This page last updated April 24, 2021


Project locationLocation
I-10 West from La Cantera Pkwy. to Ralph Fair Rd.
(For information on the various projects north of Ralph Fair Rd., see the I-10 West Projects page.)


This $70 million project added one general-purpose mainlane (for a total of three) and one high-occupancy vehicle (HOV) lane in each direction. These lanes were generally added in the previously-open center median (see cross-section below.) No entrance or exit ramp locations were changed as a result of this project, and no frontage road work was being done-- that was all completed in an earlier project.

The new lanes are all toll-free. An earlier plan for this project proposed adding two tolled managed lanes in each direction, but recent funding changes allowed the toll component to be removed. 

The westbound HOV lane starts just north of La Cantera Pkwy. There is an intermediate entrance/exit point between Camp Bullis Rd. and Dominion Dr. for traffic to exit for Boerne Stage Rd. and Ralph Fair Rd. The HOV lane then continues and ends just north of Boerne Stage Rd. where it merges into the left general-purpose mainlane. That right mainlane then ends just past the Old Fredericksburg Rd. exit. A future project will extend the third general purpose lane and HOV lane all the way to Boerne.

On the eastbound side, a third general-purpose mainlane is added to the right from the entrance ramp located just north of Ralph Fair Rd. The HOV lane  then starts on the left side under Ralph Fair Rd. There is an intermediate entrance/exit point between Stonewall Pkwy. and Camp Bullis Rd. for traffic wanting to exit to Camp Bullis Rd. and La Cantera Pkwy. The HOV lane then continues and ends just south of Camp Bullis Rd. where merges into the left general-purpose mainlane. Planning is underway to eventually extend the HOV lane south from there.



Number of access road lanes varies depending on location.
Diagrams are for illustrative purposes only and are not to scale.

How this project will help
This section of I-10 is growing rapidly and experiences recurrent daily congestion. The additional lanes provide additional capacity. The HOV lanes are the first in an envisioned system of HOV lanes in San Antonio and are intended to help reduce congestion by encouraging carpooling and mass transit usage.

For more information about local HOV lanes, see the HOV lanes page.

This project started in September 2017 and was completed in the first quarter of 2021. The new eastbound lanes opened September 26th, 2020 followed by the new westbound lanes that opened the weekend of October 17th, 2020.

Also see the HOV FAQ on the HOV lanes page.

  • The HOV merges will cause bottlenecks.
    The HOV merges themselves are not expected to create too much of an issue. Westbound, the three general-purpose lanes will also taper down to two lanes at Ralph Fair Rd., but the merging of the third general purpose lane and the HOV lane have been staggered to help ameliorate any issues. That said, the previous congestion in the Dominion area before this project was completed helped to meter traffic coming into the Leon Springs area, so with that kink now removed, the area around Ralph Fair Rd. may see some congestion as it is now the new bottleneck. This would have happened even without the HOV lane.

    On the eastbound side, the previously-existing entrances from Camp Bullis and from La Cantera and all the jostling that takes place along that stretch for folks wanting to get off onto Loop 1604 will be more of an issue than the HOV lane merge. As with the westbound side, the eastbound congestion up by Dominion and Leon Springs prior to this project helped to meter traffic coming into this area, and the addition of the third lane at La Cantera opened up some "just in time" capacity to help ease things on the 1604 approach. With the completion of this project, that upstream kink is now gone, so some additional congestion on that approach to 1604 is now likely. It will seem to be a result of the HOV merge since that's what's new in that vicinity, but it will really be more a result of the existing ramps. Again, this would have happened even without the HOV lane. Fortunately, that will all be cleaned-up with the Loop 1604 interchange project that is set to start construction in early 2022.

  • Why wasn't this expansion done when the access roads were rebuilt a few years ago?
    See the answer for the "Why is there constant construction...?" question near the top of the I-10 West Projects page.

  • Why wasn't this expansion done when the Camp Bullis and Dominion overpasses were built?
    At that time, TxDOT had not completed the required planning and environmental studies for a mainlane expansion and there was no funding for such a project. The Camp Bullis overpass was rebuilt to provide space beneath it for urgently-needed turnarounds and intersection improvements necessitated by nearby development (mainly The Rim.) The overpasses had to be lengthened and raised, which required raising the approaches on I-10. The area between Camp Bullis Blvd. and Dominion Dr. was in a floodplain, so since they were raising the roadway for the Camp Bullis overpass, they needed to address the drainage issues there, which required rebuilding the roadway. However, planners designed that section to easily facilitate the future expansion of the mainlanes.

    The Dominion overpass was built to facilitate convenient circulation and emergency access in conjunction with converting the access roads to one-way, which itself was necessitated by traffic growth in the area. (See next bullet for more details.)

    Waiting to complete those overpass projects until the mainlane expansion project development was completed and funded would have delayed the much-needed improvements they provided by nearly a decade. Like many things in life, highway improvements often are incremental due to real-world constraints.

  • The overpass at Dominion Dr. was only built to give the residents of The Dominion easy access to inbound I-10.
    This doesn't really have anything to do with this project, but this seemed like a good place to answer this persistent but false allegation among some frankly cynical people in this area. An overpass was needed between Camp Bullis Rd. and Boerne Stage Rd. to provide a convenient crossover for residents on both sides of I-10 in order to convert the access roads to one-way. Without an overpass in this area, traffic needing to go the opposite direction on I-10 would have to travel up to four miles out of the way to do so. This location was selected because it's nearly halfway between Camp Bullis Rd. and Boerne Stage Rd., because it was at a location that connected a roadway on the east side of I-10 with an already-planned arterial (Stonewall Parkway) on the west side (this arterial had been on the City of San Antonio's major thoroughfare plan for many years prior), and because it was the best location to facilitate emergency vehicle access to locations on the east side of I-10 from the fire station located on the west side of I-10 just north of there. The fact that it provided improved access to I-10 from The Dominion was certainly a beneficial consequence for them, but it was not the determining factor for the need and location for that overpass.

Below is an annotated detailed project schematic and a rendering of what the finished roadway will look like.


Click on the image below to see a detailed annotated schematic of this project


Rendering of future I-10 looking inbound north of Dominion Dr

Other sites of interest
TxDOT - I-10 from FM 3351 to La Cantera Parkway
I-10 project animation
VIA - HOV lanes

This page and all its contents are Copyright 2023 by Brian Purcell

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