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INFO: Alamo Ranch Pkwy at Westwood Loop
page last updated March 21, 2021
Alamo Ranch Parkway (ARP) at Westwood Loop
Construction underway (16% complete).
This nearly $4 million project will construct an overpass for
westbound ARP over Westwood Loop. The existing merge from
SH 151 to
westbound ARP between Loop 1604 and Westwood Loop will be
Traffic coming from SH 151 will instead continue on a new
roadway where it will merge from two lanes to one, pass over Westwood
Loop, and then merge into the existing westbound ARP approximately
1,100 feet west of Westwood Loop (i.e. in front of the Landon Ridge
assisted living center) where it will become the left lane on ARP
beyond the merge.
the existing westbound ARP approaching Westwood Loop, the concrete
island between the #2 and #3 lanes will be removed. All four lanes will
remain, but the lane assignments will change to allow only one through
lane from the second lane from the right. The two left lanes will
become left-turn only and the right lane will remain right-turn only.
ARP west of Westwood Loop, the single through lane will be joined by a
lane from the turnaround, which will then merge to the right so that a
single lane continues westbound into the merge from the new overpass
where it will become the right lane on ARP beyond the merge location.
Simplified line schematic showing planned lane configuration for westbound traffic
changes will be made to eastbound ARP or Westwood Loop.
A picture is worth a thousand words, so be sure to see
the schematic at the bottom of this page for further details.
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, 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. However, modeling showed
that a split-phase signal would have extended 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 will remove all traffic coming from SH 151 and send
Westwood Loop before merging onto ARP. This will eliminate the need for
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 will also reduce the
time needed for westbound ARP, which means additional green time will
be available for the other approaches; this should help to reduce
congestion all around this intersection.
Construction started in January 2021 and is
expected to be completed in Spring 2022.
- 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. They
the best they could with the funding they had at the time. And frankly,
volumes increased more than expected and the issue with the illegal
turning movements was not expected to be as problematic as it has
become. 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 have to do is adjust the
signal timing and that will solve the problem.
a common belief that congestion can be 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, 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 just had to add a second
through lane to handle the traffic from SH 151 to westbound
the new connector from SH 151 will narrow 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 will fly over Westwood Loop
the signal there and therefore be uninterrupted, 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 lanes from SH 151 today at
intersection. (The third through lane at the intersection services
traffic coming from Loop 1604.)
- They just added the additional
through lane on westbound ARP through the Westwood Loop intersection,
and now it will be 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 traffic volumes from Loop 1604 there, only one
lane should needed. 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.
- Traffic already backs-up at the
signal at Lone Star Pkwy. during rush hours, so this will just
Indeed, that is a likely outcome of this. As
mentioned earlier, road
in fast growing areas with limited funding will always be an exercise
in incremental improvements, and this overpass is mainly intended to
improve safety at the Westwood Loop intersection. By removing westbound
traffic from SH 151 from the intersection, it will have the
of reducing overall congestion at the intersection. So while it may
make things worse downstream at Lone Star Pkwy., it should have a net
- 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" will be
left at the western end of the new overpass for a future connection.
- 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
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