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San Antonio Area Freeway System
I-35 Northeast Expansion (NEX) Project

This page last updated September 9, 2020

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This project is currently in design
The descriptions below are based on preliminary schematics and, as a result, details may change before the project goes to construction. This project will be built using a design-build contract, so final plans will not be available before construction starts. However, they aren't expected to differ substantially from what is described below.

TxDOT has been studying an expansion of I-35 from downtown San Antonio to the Schertz area since the mid '90s. For much of the past decade, those plans necessarily included tolled lanes. But with the deprecation of tolling statewide in the past few years, the toll component of this expansion has been removed and TxDOT is now planning to expand I-35 by adding non-tolled express lanes and HOV lanes from AT&T Center Pkwy. to FM 1103. The new lanes will be elevated (double-decked) south of FM 3009 and be at-grade from there to FM 1103.

Below is complete information about the latest status of this project.



On this page


Current project plans

Background
In 1996, a Major Investment Study of the I-35 northeast corridor recommended barrier-separated express lanes, truck lanes, and/or HOV lanes. However, acute funding shortages in the early 2000s caused this plan to be shelved. In 2009, the Alamo Area Regional Mobility Authority (ARMA) resurrected the plan as a secondary phase for a local tollway system. Under this plan, the new lanes would have been built as tolled managed lanes. That plan proposed two express lanes in each direction with connectors to Loop 1604, Loop 410 North, and Loop 410 South. As the plan was further fleshed-out, it was determined that the new lanes would have to be elevated along most of the route from downtown to the FM 1103 area due to right-of-way constraints. The environmental study for that project was completed and approved in 2015.

Around that time, tolling became deprecated both locally and statewide as the legislature and citizens approved new funding sources for highways. As a result, the various local planned toll projects were successively "de-tolled" as new funding sources were identified for them. Tolls were removed from the I-35 project in June 2018.

With the toll component removed, TxDOT began work redesigning the project without tolls. Additionally, recent local transportation policy changes have promoted the addition of HOV lanes to freeway expansion projects where feasible. Given the length and commuting patterns of this corridor, as well as an already impressive 10% carpooling rate, HOV lanes were determined to be a good fit and so were added to the project.

Project description
This nearly $3 billion project will add non-tolled express lanes and HOV lanes on about 16 miles of I-35 from AT&T Center Pkwy. to FM 1103. The new lanes will be elevated (double-decked) south of FM 3009 and be at-grade from there to FM 1103. There will be two express lanes in each direction from AT&T Center Pkwy. to Rittiman Rd., two express lanes plus an HOV lane in each direction from Rittiman Rd. to the Bexar county line, one express lane and one HOV lane in each direction from Schertz Pkwy to FM 3009, and one new general-purpose mainlane and one HOV lane in each direction from FM 3009 to FM 1103.

The project will also build new interchanges above or near the existing interchanges to connect the upper level lanes to Loop 410 South, Loop 410 North, Loop 1604, and Pat Booker Rd., as well as an intermediate access point to and from the I-35 mainlanes at the Bexar county line, and make some incidental changes along those routes to accommodate the new interchange ramps. The existing interchanges at those locations will remain as they are.


Cross-section from AT&T Center Pkwy. to Rittiman Rd.


Cross-section from Rittiman Rd. to Bexar county line


Cross section from Bexar county line to FM 3009


Cross section from FM 3009 to FM 1103

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

Unlike the double-decked freeways downtown, the upper levels on this project will be express lanes, meaning there will be limited entrances and exits between FM 1103 and downtown San Antonio. The intent for the new lanes is to provide an express facility for longer-distance through traffic in the corridor, but this will also benefit the lower level by removing that long distance traffic from those lanes.

In addition to the north and south ends, motorists will also be able to enter or leave the elevated lanes at the following locations:

  • Bexar county line:
    • Southbound entrance from I-35 mainlanes to express lanes
    • Northbound exit from express lanes to I-35 mainlanes

  • Loop 1604
    • Connectors to/from Loop 1604

  • Pat Booker Rd.:
    • Entrance from Pat Booker to southbound express lanes
    • Exit from northbound express lanes to Pat Booker
    • Ramps located on Pat Booker between I-35 and Loop 1604

  • Loop 410 North:
    • Connectors to/from Loop 410

  • Loop 410 South:
    • Connector from Loop 410 to northbound express lanes
    • Connector from southbound express lanes to Loop 410
    • Southbound exit from express lanes to I-35 access road


Crossovers between the two upper levels will be provided for emergency access at three locations in the corridor: between Eisenhauer and Walzem, near O'Connor, and near Olympia Pkwy.

The project will also include several ramp revisions to accommodate the access and egress locations for the new elevated lanes. It will also add turnarounds at Schertz Pkwy. and make intersection improvements and build new overpasses at Wiederstein Rd. and at FM 2252. 

Timeline
Current funding constraints will require the project to be divided into multiple phases. Initially, funding was only available for the middle section from Loop 410 North to FM 3009, including the new connectors to Loop 410 North and to Loop 1604 to the west of I-35. In August 2019, the Texas Transportation Commission approved additional funding for the southern section from Walters St. to Loop 410 North. The remaining segment-- from FM 3009 to FM 1103, as well as the connectors to Pat Booker Rd. and to Loop 1604 east of I-35-- are currently unfunded. 

This project will be built using a design-build contract, which means that TxDOT will select a contractor who will complete the final design of the project and construct it. This process generally results in time and cost savings.


PHASE 1: Loop 410 North to FM 3009

  • Status: Funded
  • Timeline: Expected to start construction in mid to late 2021 with estimated completion in 2026
  • Cost: About $1.62 billion

This phase will include the following:

  • Two elevated express lanes and one HOV lane in each direction
  • Elevated connectors to Loop 410 North just south of the existing interchange
  • Elevated connectors to Loop 1604 west of I-35
  • Upper levels for this phase will end at the future intermediate access point at the Bexar county line
  • Emergency crossovers for the elevated lanes near O'Connor Rd. and Olympia Pkwy.
  • Additional lanes on Loop 410 to provide access to and from the new elevated lanes
  • Ramp revisions on eastbound Loop 410 from Nacogdoches to Perrin-Beitel to accommodate the new interchange ramp and smooth traffic flow approaching it


PHASE 2: Walters St. to Loop 410 North

  • Status: Funded
  • Timeline: Currently expected to start construction in 2025 with estimated completion in 2029
  • Cost: About $905 million

This phase will include the following:

  • Two elevated express lanes in each direction from AT&T Center Pkwy. to Rittiman Rd.
  • Two elevated express lanes and one HOV lane in each direction from Rittiman Rd. to Loop 410 North, including connectors to Loop 410
  • Elevated connectors to and from Loop 410 South near Rittiman Rd., terminating near FM 78
  • Southbound exit to I-35 access road north of George Beach Ave.
  • Ramp revisions on southbound I-35 between Rittiman Rd. and George Beach Ave.
  • Emergency crossover for the elevated lanes between Eisenhauer Rd. and Walzem Rd.


PHASE 3: Bexar county line to north of FM 1103.; Pat Booker Rd./Loop 1604 East interchange

  • Status: Unfunded
  • Timeline: No timeline pending funding
  • Cost: About $417 million

This phase will include the following:

  • One elevated express lane and one HOV lane in each direction from Bexar county line to FM 3009
  • One additional mainlane and one HOV lane in each direction from FM 3009 to FM 1103
  • Widened overpasses at Wiederstein Rd. and FM 2252
  • Ramp revisions between FM 3009 and FM 1103
  • New turnarounds at Schertz Pkwy.
  • Elevated connectors to Loop 1604 east of I-35
  • Elevated connectors to Pat Booker Rd.
  • Changes to Pat Booker Rd. between Loop 1604 and I-35 to accommodate new ramps

How this project will help

This corridor experiences frequently-recurring congestion due to traffic volumes regularly exceeding the capacity of the road. A study of the corridor in the 1990s determined that a significant percentage of the traffic is passing all the way through the corridor or traveling between the major interchanges, and recommended barrier-separated express and/or truck lanes to segregate that traffic from the local traffic. Those travel patterns continue today, and so the new elevated express lanes should remove most of that through traffic-- including a lot of truck traffic-- from the existing mainlanes below, thus reducing congestion there. It is estimated that when the first phase is complete, travel time on the existing mainlanes between the Bexar county line and Loop 410 North will be cut in half from about 20 minutes to less than 10 minutes. When the entire project is complete, the travel time between FM 1103 and AT&T Center Pkwy. is estimated to be reduced from about 45 minutes to less than 20 minutes.


HOV lanes are now being added to major freeway expansion projects where feasible. The intent is to encourage carpooling and use of mass transit. Each person that opts to do so is one less vehicle on the freeway, which helps to reduce congestion and pollution for everyone. A study of this corridor showed an impressive 10% of commuters were already carpooling, a number that should increase with the provision of an HOV lane. For more information about local HOV lanes, see the HOV lanes page.



Rendering of proposed northbound elevated lanes near George Beach Ave.


Schematics

Click on one of the areas on the map below to open the detailed schematics for that section of the project. The base schematics are from TxDOT with my own annotations added to help clarify and explain the various elements. Each schematic will open in a new window that you can scroll and zoom. These are the schematics presented to the public in August 2019 and are still considered preliminary and subject to change.

On the schematic, any elevated segments colored in blue are Phase 1 (called the "base" sections in the legend.) The sections colored in green south of Loop 410 (schematics C and D) are Phase 2. The sections colored in green north of the Bexar county line and east of I-35 at Loop 1604/Pat Booker Rd. (schematics A and B) are Phase 3. (See phase details above.) Other improvements shown in different colors will typically be done in the corresponding phase of the adjacent elevated section.



FAQ
Also see the HOV FAQ on the HOV lanes page.

  • Will this project be tolled?
    No. Although earlier versions of this project proposed adding managed toll lanes, funding was secured to remove the toll component. Instead, non-tolled express lanes and HOV lanes will be added.

  • Why are they building expensive elevated lanes instead of a more conventional at-grade widening?
    The existing right-of-way along most of the corridor is inadequate for a traditional widening, and because of the extensive development along the frontage roads, the cost to acquire the needed right-of-way would be more expensive-- and disruptive to the businesses and neighborhoods along the corridor-- than building the elevated lanes.

  • Why aren't there more entrances and exits from the elevated lanes?
    A study of the corridor in the 1990s determined that a significant percentage of the traffic is passing all the way through the corridor or traveling between the major interchanges, a pattern that hasn't changed much today. Therefore, the intent of the new elevated lanes is to provide an express corridor for that traffic-- including a lot of truck traffic-- thus removing it from the existing mainlanes below. Since that traffic is traveling longer-distances, they don't need those intermediate entrances and exits, and additional entrance and exits would increase the traffic volumes on those elevated lanes, defeating their purpose. Also, providing those additional entrance and exits would require additional right-of-way, which is limited in this corridor. This same concept is used on the I-35 elevated lanes in Austin, the Katy Freeway express lanes in Houston, and the Dan Ryan express lanes in Chicago, among others.

  • The lack of entrances and exits will hinder emergency response and will trap traffic on the upper level if a crash blocks all the lanes.
    To improve access for emergency vehicles and provide an "escape route" for trapped traffic, emergency crossovers will be constructed at three locations in the corridor: between Eisenhauer Rd. and Walzem Rd., near O'Connor Rd., and near Olympia Pkwy. This same approach has been used on other long dual-span roads that have limited or no access, most notably
    in Louisiana on I-10 over the Atchafalaya Swamp and on the two bridges over Lake Pontchartrain. 

  • I will not use/can't access the elevated lanes, so how will it benefit me?
    Traffic that uses the elevated lanes will not be on the mainlanes below, so this will reduce congestion there. It is estimated that when the first phase is complete, travel time on the existing mainlanes between the Bexar county line and Loop 410 North will be cut in half from about 20 minutes to less than 10 minutes.


Other sites of interest

TxDOT - I-35 from Loop 410 South to FM 1103
https://www.txdot.gov/inside-txdot/get-involved/about/hearings-meetings/san-antonio/081519.html




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This page and all its contents are Copyright 2019 by Brian Purcell

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The information provided on this website is provided on an "as-is" basis without warranties of any kind either express or implied.  The author and his agents make no warranties or representations of any kind concerning any information contained in this website.  This website is provided only as general information.  The author expressly disclaims all liability with respect to actions taken or not taken based upon the information contained herein or with respect to any errors or omissions in such information.  All opinions expressed are strictly those of the author.  This site is not affiliated in any way with any official agency.