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INFO: Alamo Ranch Pkwy at Westwood Loop
page last updated March 27, 2022
Alamo Ranch Parkway (ARP) at Westwood Loop
Construction started in January 2021 and is substantially complete
The overpass opened on or around October 16th, 2021.
This nearly $4 million project has constructed an overpass for
westbound ARP over Westwood Loop and the existing merge from
SH 151 to
westbound ARP between Loop 1604 and Westwood Loop has been
Traffic coming from SH 151 instead now continues on a new
roadway where it merges from two lanes to one, passes over Westwood
Loop, and then merges into the existing westbound ARP approximately
1,100 feet west of Westwood Loop where it becomes the left lane on ARP
beyond the merge.
the westbound access road from Loop 1604 approaching Westwood Loop, the previous concrete
island between the #2 and #3 lanes has been remove and the lane assignments adjusted.
Simplified line schematic showing lane configuration for westbound traffic
changes were made to eastbound ARP or Westwood Loop.
a common misconception that ARP in this area is SH 151 and/or
maintained by TxDOT. However, the state's responsibility ends about 400
feet east of Westwood Loop, and this location is not in the City of San Antonio, so this intersection is
responsibility of Bexar County. However, the county and state agreed to
build this overpass as a joint project with TxDOT designing it and
managing the project to completion. Funding is from state safety funds.
this project will help
With the completion of the SH 151-ARP
2017, the westbound ARP lanes had to be segregated to prohibit left
turns onto Westwood Loop for traffic coming from Loop 1604 and
turns onto Westwood Loop for traffic coming from SH 151. This
substantially more problems than planners expected. After many
reports and observations of drivers violating the turn restrictions and
the resultant crashes, and attempts to mitigate the problem with
bollards and a concrete island, engineers evaluated several additional
options including a "split-phase" signal and a "super street" configuration. However, modeling showed
that a split-phase signal would have lengthened signal cycle times
and further exacerbated delays at the intersection, and
existing and future traffic volumes would have rendered most of the
other options evaluated obsolete within a few years. An overpass was
determined to be the best long-term solution.
overpass removes all traffic coming from SH 151 and sends
Westwood Loop before merging onto ARP. This eliminates the need
the segregated lanes and associated turn restrictions on westbound ARP,
thus allowing for all turning movements for traffic coming from Loop
1604. Removing all the SH 151 traffic also reduces the
time needed for the westbound ARP signal (for traffic coming from Loop
1604), which means additional green time is available for the
drawback to this change is that traffic headed westbound on SH 151 no
longer can no longer directly access Westwood Loop. Those drivers can
use the turnarounds at Lone Star Parkway or at Culebra instead.
- What other improvements were
considered for ARP and Westwood Loop?
Previously-considered plans to
convert the intersection to a
"super street" configuration were dropped as was a
previous proposal to change the westbound signals
to a "split-phase" where the approaches from SH 151 and
Loop 1604 would each have had their own green phase, thus allowing
right turns from
each (similar to the McCullough exit from southbound I-35 downtown.) It
was determined that changing to a split-phase would
have extended the cycle length excessively, thereby increasing
- Why didn't they build this when
they built the overpass over Loop 1604?
This intersection is technically beyond the state's right-of-way, so it
was out-of-scope for the original project, plus it would
have appreciably increased the cost of the project. After completion of that project, traffic
volumes increased more than expected, and the issue with the illegal
turning movements was not expected to be as problematic as it became. It's worth keeping in mind that road
in fast growing areas with limited funding will always be an exercise
in incremental improvements and occasional trial-and-error.
- All they had to do is adjust the
signal timing and that will solve the problem.
a common belief that congestion could have been solved by simply
adjusting the signal timing. In some specific cases, that can be true,
but at a very busy intersection like this where there has to be
sufficient green time for a plethora of movements on every cycle, the
signals can only be optimized so much before the laws of physics win.
For example, the green time on Westwood Loop could be extended
to help clear
out the peak period backups that occur there, but that means the light
will stay red longer for ARP, which then increases the congestion
there. If the green time on ARP is then increased to ease those
that means the light will stay red longer for Westwood Loop and you're
back where you started. So as you can see, it's really not as easy as
- Why couldn't they just change the
signals on westbound ARP to operate like the signals on I-35 at
configuration, known as a "split-phase" signal, was evaluated. However,
the extra green time that would have been needed for the extra phase
would have extended the red time on all the other approaches by about 20%, which
would have increased the congestion there. (The traffic volumes at the
I-35/McCullough intersection are low enough that the split-phase does
not cause excessive delays.)
- They had just added a second
through lane to handle the traffic from SH 151 to westbound
the new connector from SH 151 narrows from two lanes to
merging with ARP. How is this an improvement?
That's because this is not an apples-to-apples
comparison. Since SH 151 traffic now flies over Westwood Loop
the signal there, that single lane will
able to move twice as much traffic over a given period than each lane
the signalized intersection. Therefore, that single lane on the
overpass is roughly equivalent to the two previous lanes from SH 151 at
intersection. (The third through lane at the intersection serviced
traffic coming from Loop 1604.)
- They had just added the additional
through lane on westbound ARP through the Westwood Loop intersection,
and now it's been taken out? That seems like it was a waste of money.
The additional through lane (known as an auxiliary lane) was intended
to be a temporary solution and provide relief until the overpass could
be built, and funding for the overpass was obtained a bit faster than
expected. Given the traffic volumes coming from Loop 1604 there,
lane should be needed at that location. If future traffic volumes
necessitate an additional
through lane, the dedicated lane added from the turnaround can be used
and the turnaround switched to a yield. However, that would likely need
be done in conjunction with an expansion of ARP further west.
- Traffic already backed-up at the
signal at Lone Star Pkwy. before this project, so now this just
that's true. But in reality, all the traffic that backs up there
now was going to back up there anyway without the overpass, so
this project really didn't cause that. Instead of that westbound
backing up at two intersections like it did before, now it only
backs up at the one (Lone Star.) As
mentioned earlier, road
in fast growing areas with limited funding will always be an exercise
in incremental improvements, and this overpass was primarily intended
to address the specific safety issue at Westwood Loop of people turning
illegally and causing lots of crashes. So while it may
seem like it's making things worse downstream at Lone Star Pkwy., it's really not, and it is
still having a net overall benefit by helping to improve safety at Westwood Loop.
- Are there any plans for an
eastbound overpass at Westwood Loop?
Not at this time.
- Are there any plans to extend the
expressway west from Westwood Loop?
While ARP was designed with sufficient right-of-way to allow for a
expressway between the existing lanes (similar to Wurzbach Parkway),
are no plans for that at this time. However, a short "stub" was built
at the western end of the new overpass for a future continuation of the
- Are there any plans to extend SH
A plan released in 2009 would have extended SH 151 westward as
tollway, but that was later scrapped. TxDOT currently has no plans to
extend SH 151 past Loop 1604. Alamo Ranch Parkway is currently
a county road.
did not have a
"consumer-friendly" schematic available for this project, so yours
truly created one based on the official construction plans made
available by TxDOT. Note that the schematic shows the approximate
locations and should not be considered to be definitive. Instead, it is
intended to convey the general plan. It will
open in a new window that you can scroll and zoom.
Click above to see the
annotated schematic for