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Antonio Area Roads
151/Alamo Ranch Parkway/Loop 1604 area
page last updated January 28,
the history of various projects in the Loop 1604 - SH 151 -
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."
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
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
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
(at right) marking the beginning of Bexar County jurisdiction on Alamo
by Brian Purcell)
from Loop 1604
southbound to SH 151 eastbound removed all that traffic from
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.
Original TxDOT project (completed in 2017)
The original TxDOT project in 2017 constructed a flyover
southbound Loop 1604 to SH 151 and an overpass connecting
SH 151 to
Alamo Ranch Parkway at
Westwood Loop. This overpass
a previous signalized
intersection for eastbound traffic crossing Loop 1604 and a circuitous
route along the Loop 1604 access roads for westbound traffic.
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
1604 freeway to the south.
Generalized 151/1604 area traffic
patterns before and after ARP overpass
Illustrates a major intent of the original state project
to remove traffic from the overcrowded 1604 access roads
and 1604/Culebra intersection
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 signal (completed
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
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 fatal crash at the intersection in that interim period.
Loop turn issues
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
approach lanes. However, many drivers simply ignored these and drove
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.
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.
Installation of pylons on westbound ARP at Westwood Loop to
These were subsequently replaced by a concrete island (visible in the
photo at the top of this page.)
courtesy of Josh Donat,
ARP/Westwood Loop additional
westbound through lane project (completed
in May 2019)
to increasing traffic congestion on westbound
Parkway/Westwood Loop intersection, the county built an
additional lane on westbound ARP through the Westwood Loop
additional lane allowed the left lane
coming from SH 151, which used to be a left turn only lane, to
left turn/straight option lane instead, i.e. it provided two through
lanes from 151 through the intersection.
at Westwood Loop
finally resolve the illegal turning and associated safety issues at
Loop discussed above, funding was obtained to build an
westbound ARP traffic over Westwood Loop. The overpass opened in mid
October 2021. See the Alamo
Ranch Parkway at Westwood Loop project page for
ramp to northbound Loop 1604 (construction starting in 2023)
The obsolete hairpin or hook entrance to northbound Loop 1604 from SH
replaced in the near future by a new direct connector as part of an expansion
project on SH 151.
- Why did they make a highway end
at a traffic signal?
It may seem like that's the case since the 151
continue straight onto Alamo Ranch Parkway (ARP), but the point of the
overpass from 151 was to provide a direct connection from 151 to ARP,
and ARP is a surface street with
signalized intersections, so that's just how
it worked out. This situation is not unheard of and is found in many
Since ARP lies directly ahead of the end of 151, the route must
inherently go straight
from 151 to ARP. Therefore, it gives the impression that the
highway keeps going over 1604 and Westwood Loop and then encounters a
you'll notice that the speed limit decreases to 45 mph as you approach
and there are large yellow "FREEWAY ENDS - SIGNAL AHEAD" signs that
tell you the
freeway is ending and that you are transitioning to a surface
street. Therefore, the
overpasses are really just a long, straight exit from
151 to ARP-- it just
happens to be at the end of the
freeway. Furthermore, with the addition of the overpass at Westwood
Loop, traffic from SH 151 now is winnowed down to a single
merges onto ARP more like a typical exit ramp, which also should signal
to drivers that they've left the freeway.
is a case where drivers need to pay attention and adjust their
"Freeway ends" warning signs on
westbound SH 151 approaching Alamo Ranch Parkway
- This configuration causes
traffic from 151 to back up when it reaches ARP.
traffic queues at the signal at Lone Star Parkway, but this happens
leaves a freeway and encounters a signalized intersection such as on
exit ramps and access roads elsewhere in the city, and where freeways
end and become surface
roads (for example, southbound Loop 1604 at US 90.) As mentioned above,
exit from 151 to ARP-- it just
happens to be a straight exit at the end of 151. As such,
no reason to expect this location wouldn't have backups like any other
highly-trafficked exit from a freeway to a surface road.
traffic backed up there prior to the overpasses being
never claimed nor intended that the overpasses would solve
the overpass from 151 is an improvement over the previous
from 151 to ARP via the Loop 1604 access roads and Culebra
turnaround, and the Westwood Loop overpass has solved the previous
problem of numerous crashes caused by illegal turning there as it was
intended to do.
cause of the congestion is simply that the signals at Lone Star Parkway
cannot provide sufficient throughput for the peak traffic volume on
ARP. The wide median on ARP makes it very difficult to design an
efficient signal cycle. The same problem existed on Wurzbach Parkway at
NW Military Hwy.; a project that was completed there in 2022 realigned
the left turns to allow for more efficient signal phasing. A similar
project here-- or perhaps another alternative intersection design--
could provide relief.
- Why didn't they extend
overpass over Westwood Loop when the overpass from 151 was built?
There were a few reasons. First, the state's
right-of-way doesn't extend that far, so this
intersection was outside the scope of that project aside from some
incidental work. In
addition, it would
have increased the cost of that project, which was already
limited. And, frankly, planners just did not expect the issues that
manifested there. Road
in fast growing areas with limited funding will always be an exercise
in incremental improvements and some trial and error.
- Why didn't they build an
eastbound overpass at Westwood Loop when they built the westbound
westbound overpass over Westwood Loop was built specifically to solve
the issue of drivers making illegal turns to Westwood Loop and
causing crashes, and so it was awarded safety funding on that basis.
The process to obtain funding requires demonstrating
that the proposed project will solve the identified problem; an
eastbound overpass in this case would not have done anything to solve
the illegal/unsafe turning issue, and there wasn't a similar issue on
the eastbound side, so thatís
why an eastbound overpass wasnít included.
- Are there any plans for
an eastbound overpass at the intersection of ARP and Westwood Loop?
Not at this time.
- What other improvements were
considered for ARP and Westwood Loop?
A proposal to convert the intersection to a
"superstreet" configuration was considered as was a 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 time, thus allowing left and
right turns from
each lane (similar to the McCullough exit from southbound I-35
was determined that changing to a split-phase would
have extended the signal cycle length considerably (essentially
from a four-way to a five-way intersection), thereby increasing wait
times by up to 20% in all directions.
- I heard/remember that an
endangered spider caused this mess.
Not really, and in fact, it actually made things better. Prior
the overpass, there was an earlier plan for SH 151 to
Loop 1604 and then intersect the southbound Loop 1604 access road at
The discovery of a
federally-protected endangered spider during
construction forced TxDOT to stop work and redesign the
project to go over the protected karst habitat
of that spider. The redesign actually resulted in a few improvements:
in the original project,
the east-west roadway connecting SH 151 to ARP would have
southbound Loop 1604 access road at a signalized intersection, meaning
traffic on one of those roadways would have a red signal to allow
the other roadway to proceed. You can imagine the backups this would
cause today, not only on 151 and ARP, but also on the southbound access
road. Today, of course, the east-west traffic goes completely
over the access road, and the only signal is for a westbound to
southbound Loop 1604 left turn, which only stops eastbound traffic
and doesn't stop westbound traffic at all.
the flyover from southbound Loop 1604 to 151 was not included in the
original project. With that project, traffic on southbound
Loop 1604 wanting to go to eastbound 151 would have exited onto the
Loop 1604 access road just south of Culebra, and then have made a left
turn to go under Loop 1604 and onto SH 151 at the
aforementioned signalized intersection. However, while the project was
being redesigned, additional funding became available to include the
flyover in the revised project.
So actually, in the end, the spider resulted in a better outcome.
Original plan for SH 151/Loop 1604/Alamo Ranch Pkwy. intersection that was
cancelled due to an endangered spider being found during construction
- Why didn't they plan for the
increase in traffic caused by the overpass?
theory, the new overpass would only be carrying traffic that was
already going from SH 151 to ARP via the convoluted access
so it really shouldn't have increased traffic. But improving that
connection also likely triggered something known as "latent demand" or
"induced demand". This when a
significant number of people were using
alternate routes to avoid the congestion and/or inconvenience of the
previous 151 to ARP route, and after thenew overpass opened, they
started using it since it was
now better than their previous route (or at least perceived to be.)
While planners can do studies to
attempt to estimate what that latent demand might be, it's
virtually impossible for anyone without a crystal ball to know for sure
what that demand is until the new road opens and that traffic
especially in an area like Alamo Ranch that's growing so
Why is there
a signalized intersection for the ramp to southbound Loop 1604
instead of a flyover?
There was not enough funding for a flyover for that connection, and,
the road network in this part of the city, planners estimated that
there should not be a
considerable amount of traffic making that turn (at least, not enough
to justify the cost of a flyover), so this was
the compromise. Furthermore, the peak period for traffic making
that turn is in the evening when eastbound ARP/151 traffic is
typically lighter. Traffic counts on that ramp since it has
opened have validated planners' assumptions.
- Why didn't they make the flyover
from southbound 1604 to 151 two lanes?
Funding for that connector was limited.
Furthermore, there are not enough lanes downstream on 151 to receive
two lanes from the connector plus the lanes coming from ARP plus the
ramp from northbound 1604. Making that connector two lanes would have
resulted in a pretty significant bottleneck where it merges into 151.
That said, a future upgrade to that connector is being discussed.
- Why did they close the Wiseman
exit ramp on eastbound SH 151?
Technically, there wasn't an exit there before. Traffic
coming from Loop 1604 previously was on the access road and could
either enter the SH
151 mainlanes just before Wiseman or stay on the access road to
Wiseman. Since the new
connector from 1604 enters the 151 mainlanes
directly and not the access road, it bypasses that earlier option.
- Okay, then why didn't they add an
eastbound exit to Wiseman?
The reason why they didn't add an eastbound exit to
Wiseman from the Loop 1604 flyover is because there isn't sufficient
space to do so. From the end of the on-ramp coming from
northbound 1604, they would need a minimum of 1,500 feet for a weave
area that would be safe and minimize possible conflicts. At
the 1,500 foot mark, the exit to Wiseman would be quite steep and would
the end of that off-ramp much too close to the Wiseman intersection
(less than 500 feet.) This would require drivers wanting to turn right
Wiseman to make a sharp cut across the access road, which
might be difficult if more than a few vehicles were stopped at the
signal and would mean that traffic would likely
up onto the exit ramp.
- Will the hairpin/hook connector
151 to northbound 1604 be replaced?
TxDOT did not have enough funding in the previous projects to
ramp. However, a new direct connector for that turn will be included
in the upcoming project to widen
- Why didn't they build
a flyover or ramp
from eastbound ARP to northbound Loop 1604?
Two reasons-- there was not enough funding or demand to build such a
connector. They used the funding they did
have on the most urgent need-- the southbound 1604 to eastbound 151
connector. But planners are studying it as part of a larger study for
future improvements to the Loop 1604 corridor.
- Why is there no entrance to SH
151 from Culebra?
The decision to not include an entrance
from Culebra to SH 151 was based on several factors:
mentioned a few
bullet points above, planners are considering long-term plans
that would expand the southbound Loop 1604 flyover to SH 151.
To do so
actually require constructing a new flyover. If they do that, they
envision retaining the existing flyover and repurposing it as a
connector from the southbound Loop 1604 access road to SH 151.
- The volume of traffic now and especially
in the future needing to exit from southbound 1604 to ARP likely
exceeds that of
traffic needing to get from Culebra to SH 151; this made an
exit for ARP a higher priority than an entrance from Culebra.
- There is only room for one surface ramp in that
area and the cost for a "braided" ramp was prohibitive.
are reasonable alternatives to get to SH 151 from Culebra
there are very limited possibilities to get from southbound 1604
to ARP that don't add significantly to existing congestion (i.e.
southbound Loop 1604 at Culebra.).
entrance from Culebra onto the SH 151 connector would have
significant congestion on the
connector during most of the day caused
by the stream of slower-moving traffic entering from Culebra trying to
into a single lane with the stream of faster-moving traffic coming from
Loop 1604, all
while moving uphill to the connector. This congestion would have
backed-up onto Loop 1604 as well as onto the access road and possibly
intersection at Culebra.
- They should fire the idiot who
If after reading the information above you still feel that way, see this