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SH 151/Alamo Ranch Parkway/Loop 1604 area

This page last updated February 11, 2024

This page summarizes the history of various projects in the Loop 1604 - SH 151 - Alamo Ranch Parkway (ARP) - Westwood Loop area, discusses future plans, and answers frequently asked questions about this oft-maligned intersection.

The history of projects around this location illustrate the incremental method that road improvements often take and epitomizes the old addage "Don't let the perfect be the enemy of the good."

Digger sign

Looking for information about the current interchange construction? See the SH 151 Expansion Project page.

Many people just assume that either the City of San Antonio or TxDOT is responsible for all the roads in this area. However, that's not the case. TxDOT is responsible for SH 151 and Loop 1604 and their access roads. Bexar County is responsible for Alamo Ranch Parkway starting about 800 feet west of Loop 1604 (including the intersection at Westwood Loop), while TxDOT is responsible to the east of that point. There are signs on Alamo Ranch Parkway that mark where Bexar County's jurisdiction begins (see below.) The City of San Antonio is not responsible for any of the roads in this immediate vicinity.

Bexar County Maintenance sign

Sign (at right) marking the beginning of Bexar County jurisdiction on Alamo Ranch Parkway
(Photo by Brian Purcell)


Project History

Original TxDOT project (completed in 2017)
The original TxDOT project in 2017 constructed a flyover from southbound Loop 1604 to SH 151 and an overpass connecting SH 151 to Alamo Ranch Parkway at Westwood Loop. This overpass replaced a previous signalized intersection on Loop 1604 for eastbound traffic crossing from ARP to 151, as well as a circuitous route along the Loop 1604 access roads for westbound traffic.

The flyover from Loop 1604 southbound to SH 151 eastbound removed all that traffic from the southbound access road and the previous signalized intersection required to cross Loop 1604 and enter SH 151. The new overpass connecting SH 151 to ARP provided a direct connection between those roadways. Prior to that, westbound traffic from 151 to ARP had to use the northbound 1604 access, take the turnaround at Culebra, then use the southbound 1604 access road to reach ARP. (See map below.)

The flyover and overpass allowed the previous signalized at-grade intersection on Loop 1604 at SH 151 to be removed, which was necessary in order to extend the Loop 1604 freeway to the south.

Work on this project began in April 2015. The flyover from southbound Loop 1604 to SH 151 opened to traffic July 30, 2016. The ARP overpass opened on December 17, 2016.

Traffic patterns map

Generalized 151/1604 area traffic patterns before and after ARP overpass
These maps illustrate a major intent of the original state project to remove traffic from the overcrowded 1604 access roads and 1604/Culebra intersection.

ARP/Westwood Loop traffic signal (completed in 2017)
The intersection at ARP and Westwood Loop was originally a two-way stop (stop signs on Westwood Loop), then a four-way stop. To accommodate the expected increase in traffic, the county planned to have a traffic signal at ARP and Westwood Loop ready in time for the opening of the overpass from SH 151 in December 2016. However, the Casa Blanca theater was announced after the county had already started their planning process for the signal, so it required engineering for the signal to be paused while the county waited for the driveway and turn lane plans from the theater developer, thus delaying the signals until after the overpass opened. The signals finally went into operation on February 27, 2017. Unfortunately, there was a highly-publicized fatal crash at the intersection in that interim period.

ARP/Westwood Loop turn issues
Due to numerous issues with drivers making aggressive lane changes in order to make a right or left turn at Westwood Loop from westbound 151/ARP, flexible pylons were installed separating the SH 151 and Loop 1604 approach lanes. However, many drivers simply ignored these and drove over them or made illegal turns at the intersection. The pylons were replaced a few months later with a concrete island, after which some drivers continued to make illegal turns, often causing crashes.

Suggestions for a "split-phase" signal were considered but dropped after modeling showed that the increased signal cycle time required for it would substantially increase congestion on all approaches.

Pylons on ARP

Installation of plastic pylons on westbound ARP at Westwood Loop to try to prevent problematic lane changes
These were subsequently replaced by a concrete island (visible in the photo at the top of this page.)
(Photo courtesy of Josh Donat, TxDOT)

ARP/Westwood Loop additional westbound through lane project (completed in May 2019)
Due to increasing traffic congestion on westbound SH 151 at the Alamo Ranch Parkway/Westwood Loop intersection, the county built an additional lane on westbound ARP through the Westwood Loop intersection. This additional lane allowed the left lane coming from SH 151 — which used to be a left turn only lane — to become a left turn/straight option lane instead, i.e. it provided two through lanes from 151 through the intersection along with a lane from 1604. The left lane then merged right after the intersection.

Westbound ARP overpass at Westwood Loop (completed in October 2021)
To finally resolve the illegal turning and associated safety issues at Westwood Loop discussed above, funding was obtained to build an overpass for westbound ARP traffic over Westwood Loop. The overpass opened in October 2021.

Westbound SH 151 ramp to northbound Loop 1604 (construction underway)
The obsolete J-hook entrance ramp to northbound Loop 1604 from SH 151 is being replaced by a new direct connector as part of the expansion project on SH 151.