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San Antonio Area Freeway System
PROJECT INFO: SH 151 from Loop 410 to Loop 1604

This page last updated May 21, 2019

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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 page will be updated when final schematics for the project are available.

Project location Location
SH 151 from Loop 410 to Loop 1604

Status
Advanced planning (see timeline below.)

Description
This $80 million project will widen SH 151 from four to six lanes (i.e. three lanes each way) with a concrete center barrier. It will also build a new connector from westbound SH 151 to northbound Loop 1604 to replace the existing hairpin curve there and adjust the northbound Loop 1604 exit to Culebra. New turnarounds will be added at Military Dr., Westover Hills Blvd., and Wiseman Blvd., a new eastbound exit ramp to Military Dr. inside Loop 410 will be built, and several existing right turn lanes at various intersections will be extended and some new right turn lanes built.

The new lanes on SH 151 will be added in the existing grassy median between the eastbound and westbound lanes. In fact, the median was originally planned for this eventuality.

EXISTING CROSS SECTION



FUTURE CROSS SECTION



NOTE
The number of mainlanes shown is the number of through lanes and does not include auxiliary or transitional lanes.
The 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
The added lanes are needed to provide capacity for current and future traffic volumes in this corridor. Traffic volumes have increased substantially since the opening of the flyover connectors at Loop 410. 

The connector from westbound SH 151 to northbound Loop 1604 will 
alleviate the congestion caused by the current hairpin ramp there.

The turnarounds will help reduce congestion in those intersections, especially at Military Dr. The new ramp to Military Dr. inside Loop 410 will allow that traffic to bypass the signalized Loop 410 intersections.

Preliminary modeling of the improvements vs. doing nothing shows a decrease in 2045 travel times of 34% to 60% depending on direction and time of day.

Timeline
Construction is expected to start in mid 2021 and take about three years to complete.

FAQ

  • The problem isn't that there aren't enough lanes on SH 151, it's the bottleneck at Loop 1604.
    That's partially true. First of all, there is indeed a capacity problem on SH 151. For example, traffic backs-up on eastbound SH 151 in the morning. Since this is headed away from the Loop 1604 interchange, that's obviously not the cause. Adding the extra lane will help alleviate that congestion.

    On the westbound side, yes, the bottleneck at the exit to Loop 1604 northbound is a major factor in the recurring congestion there during the afternoon rush hour. The new connector from westbound SH 151 to northbound Loop 1604 that's planned as part of this project should resolve that. Even so, traffic volumes headed westbound now and in the future warrant another lane being added to the corridor. In fact, since the flyovers at Loop 410 opened, traffic counts in this corridor have increased substantially.

    Finally, the backup at Westwood Loop and Alamo Ranch Parkway that spills back onto SH 151 has been alleviated with the recent completion of a project to add an additional westbound through lane at that intersection and will be further resolved in a few years with the planned construction of a westbound overpass there. (That is a county project and is not part of this project.)

  • Why didn't they build the westbound SH 151 connector to northbound Loop 1604 when they built the other flyover there?
    There wasn't funding for that connector at that time. In fact, the flyover that's there now was not even originally part of the project that built it; it was added later when additional funding for it became available.

  • Why was that hairpin ramp built that way?
    That ramp was built 20 years ago when the Loop 1604 overpass at Culebra was built and
    traffic volumes were substantially less than they are today. The proximity of the Culebra exit ramp required the entrance from 151 to be pulled back as far as possible to provide adequate merging space-- this resulted in the tight ramp that there's now. Given the low traffic volumes at that time and limited funding, this was considered to be adequate for the time being. A "braided" entrance ramp going from the access road over the Culebra exit was briefly considered a few years back. However, it was determined that it was not the best long-term solution and that waiting a little longer to be able to build the direct connector was the best option.

  • Will the endangered spider delay this project?
    Not likely. The spider that caused the original project to build an underpass for SH 151 under Loop 1604 to be cancelled and re-designed is actually not on the endangered list anymore. That said, the area is known to be habitat for other endangered spiders, so TxDOT will have to consult with the US Fish & Wildlife Department to ensure that approved mitigation plans are in-place. Since this is a known issue this time around, it is not expected to significantly delay the project.


Schematic
Click on the image below to open the detailed schematic for this project from TxDOT with my own annotations added to help clarify and explain the various elements. The schematic will open in a new window that you can scroll and zoom.

 (Note: The schematic is somewhat large and may take a few seconds to open.)




Other sites of interest
TxDOT - SH 151 from Loop 1604 to I-410
https://www.txdot.gov/inside-txdot/get-involved/about/hearings-meetings/san-antonio/052119.html




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

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