Antonio Area Freeway System
151/Alamo Ranch Parkway at Loop 1604
page last updated May 25,
the history of various projects in the Loop 1604 - SH 151 - Alamo Ranch
Westwood Loop area, discusses future plans, and answers frequently
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; TxDOT is responsible to the east of
that point. There are signs on Alamo Ranch
Parkway that mark where Bexar County's jurisdiction begins. 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 Ranch
from Loop 1604
southbound to SH 151 eastbound removed all that traffic from the
southbound access road and the previous
signalized intersection to cross Loop 1604. The new
overpass connecting SH
151 to ARP improved the connectivity between those
this was done to reduce congestion on both Loop
1604 access roads south of Culebra as SH 151 traffic destined for ARP
and southbound Loop 1604 no longer has to use those access roads and
the turnaround at Culebra. In
addition, traffic from
Culebra headed to SH 151 now uses routes other than the southbound
Original TxDOT project (completed in 2017)
The original TxDOT project constructed a flyover
southbound Loop 1604 to SH 151 and an
overpass connecting SH 151 to Alamo Ranch Parkway (ARP) 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 signalized at-grade
intersection on Loop
1604 at SH 151 to be removed, which was necessary to extend the Loop
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. However, the Casa Blanca theater was announced
after the county had already substantially completed their plans for
the signal, so it required the signal to be redesigned to accommodate
the new development, thus delaying the
project. The signals
finally went into operation on February 27, 2017.
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 ARP,
flexible pylons were installed separating the SH 151 and Loop
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.
for a "split-phase" signal were considered but dismissed after modeling
showed that the increased cycle time required for it would
substantially increase congestion on all approaches.
Pylons being installed on westbound ARP at Westwood Loop to prevent
lane changes; these have since been replaced by a concrete island
(Photo courtesy of Josh Donat,
ARP/Westwood Loop additional
westbound through lane project (completed
in May 2019)
to increasing traffic congestion on westbound SH 151
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 become a
left turn/straight option lane instead. This should reduce the backups
from ARP onto
Westbound SH 151
flyover to northbound Loop 1604 (planned)
infamous hairpin entrance to northbound Loop 1604 from SH 151 will be
replaced in the near future by a new direct connector as part of an expansion
project on SH 151.
Westbound ARP overpass
at Westwood Loop (planned)
county has obtained funding to build an overpass for
westbound ARP traffic over Westwood Loop. The expected timeline for
that project is 3-5 years. This project should further reduce
congestion on westbound SH 151 approaching this area as well as allow
for the removal of the turn restrictions that are there today.
Additionally, the signals there won't have to service as much
westbound traffic; this means they should be able to dedicate more
green time to the other approaches, which should ease congestion
overall. Although this is technically a county project, TxDOT will take the lead in the design.
This project epitomizes the concept of "Don't let the perfect be the
enemy of the good."
- Why did they make a highway end
at a traffic signal?
may seem like that's the case since the 151 mainlanes
straight onto ARP, but traffic coming from 151 had to go somewhere onto
ARP, and ARP is a surface street with intersections, so that's just how
it worked out. This situation is not uncommon and is found in
many other cities.
The goal of the original TxDOT project was to provide a
direct connection from 151 to ARP so that traffic would no longer have
to follow the access road to Culebra, turnaround, and go back on the
opposite access road to reach ARP, which
substantial congestion on those access roads (see
traffic patterns maps above.) Also,
the project was needed so that traffic
going from ARP to 151 would not have to cross Loop 1604 at a the
signalized intersection, which had to be removed in order to upgrade
Loop 1604 to a freeway.
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 suddenly ends at an intersection, but
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
overpass is really just a long, straight exit from
151 to ARP-- it just
happens to be at the end of the
is a case where drivers need to pay attention and adjust their
expectations. It's a location that required an
anomalous design (a situation complicated by an
endangered species finding; more on that below.) Perhaps drivers would
have more intuitively
understood that they're exiting the freeway
if the 151 access road had been extended over Loop 1604
of the mainlanes and ARP-bound traffic had to
"exit" and use
there still would have been the same issues where that access road
connected to ARP.
- This configuration causes
traffic from 151 to ARP back up at Westwood Loop.
traffic queues at that signal just as it does anywhere traffic
leaves a freeway and encounters a controlled intersection such as it
exit ramps and access roads elsewhere in the city and where freeways
end and become surface
roads (e.g. Loop 1604 at US 90.) As mentioned above, this is
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. Furthermore,
traffic backed up there prior to the overpass being built and
never been claimed that the overpass would solve that. Instead,
the direct overpass is an improvement over the previous circuitous
from 151 to ARP via the Loop 1604 access roads and Culebra
- Couldn't they have extended the
overpass over Westwood Loop?
but the state's right-of-way doesn't extend that far, plus it would
have substantially increased the cost of the project. They
the best they could with the funding they had. Road
in fast growing areas with limited funding will always be an exercise
in incremental improvements.
the county has since obtained funding to construct an overpass for
westbound ARP over Westwood Loop. It is anticipated that
work could begin in 3-5 years.
- Are there any future plans to
improve the intersection of ARP and Westwood Loop?
Yes, the county has obtained
funding to construct an overpass for westbound ARP over Westwood Loop.
It is anticipated that
work could begin in 3-5 years.
- What other improvements were
considered for ARP and Westwood Loop?
convert the intersection to a
"super-street" configuration have been tabled for now as has a
previous proposal to change the westbound signals
to a "split-phase" where the SH 151 and Loop 1604 approaches would
have had their own green phase, thus allowing left and 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
congestion, and that doing so was unnecessary as there are
convenient routes to reach those destinations.
- Couldn't they have built an
underpass under Loop 1604 instead of the overpass?
actually was the original plan, but the discovery of a
federally-protected endangered spider during construction of that
forced TxDOT to redesign the project to go over the protected habitat
of that spider. The good news is that the direct connector
southbound Loop 1604 to 151 was not included in that original project,
so the discovery of the spider resulted in that improvement
- Why didn't they plan for the
increase in traffic caused by the overpass?
Obviously, planners knew that traffic would increase with
opening of the overpass. The challenge is
something known as "latent demand" and "induced demand". These are the
significant number of people who were
alternate routes to avoid the congestion and/or inconvenience of the
previous 151 to ARP route. 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
that demand is until the new road opens and that traffic materializes,
especially in an area like Alamo Ranch that's growing so rapidly. That
said, the overpass and ARP itself have ample capacity for now.
- Why is there
a signalized intersection for the ramp to southbound Loop 1604
instead of a flyover?
was not enough funding for a flyover for that connection, and, given
the road network in this part of the city, planners estimated that
there should not be a
considerable amount of traffic making that turn, so this was
compromise. 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 did they only build the
connector from southbound 1604 to 151?
The simple answer is funding. They only had enough
to construct one connector, and that's the one with the most traffic
and most "bang for the buck". A new direct connector from westbound 151 to
northbound 1604 will be built as part of an upcoming
expansion of SH 151.
- Why didn't they make the
connector 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
from the connector plus the lanes coming from ARP plus the entrance
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 envisioned.
- 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 was on the access road and could either enter SH
151 just before Wiseman or stay on the access road to Wiseman. The new
connector from 1604 enters the 151 mainlanes
directly, not the access road.
said, the reason why they
didn't add an eastbound exit to
Wiseman from the Loop 1604 connector is because there wasn'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 congestion. At
1,500 foot mark, the exit to Wiseman would be quite steep and would put
the end of the off-ramp much too close to the Wiseman intersection
(less than 500 feet), which means drivers wanting to turn right onto
Wiseman would have to make a sharp cut across the access road, which
might be difficult if more than a few vehicles were stopped at the
signal. It would
also mean that traffic would likely back up onto the exit ramp during
- Will the hairpin connector from
151 to northbound 1604 be replaced?
not have enough funding in the 1604/151/ARP project to improve that
ramp. However, a new direct connector for that turn will be included
in a future project to widen SH 151.
- Will there be a flyover or ramp
eastbound ARP to northbound Loop 1604?
there are no plans at this time for such a connector. Planners are
keeping it in mind as they make other improvements in the area so as to
not prevent one from eventually being built.
- Why is there no entrance
ramp to SH 151 from Culebra?
The decision to not include an entrance
from Culebra to SH 151
was based on several factors:
- The volume of traffic now and especially
in the future
needing to exit from southbound 1604 probably 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 ramp in that area.
are reasonable alternatives to get to SH 151 from Culebra whereas
there are very limited possibilities to get from southbound 1604
entrance from Culebra onto the SH 151 connector would have resulted in
significant congestion on the
peak periods caused
stream of slower-moving traffic entering from Culebra trying to merge
with the stream of faster-moving traffic coming from Loop 1604, all
moving uphill to the connector. This congestion would have
onto Loop 1604 as well as onto the access road and possibly into the
intersection at Culebra.
- They should fire the idiot who
If after reading the information
above you still feel that way, see this page.