Antonio Area Freeway System
INFO: SH 151 from Loop 410 to Loop 1604
page last updated December 8,
project is currently in design
descriptions below are based on preliminary schematics and, as
result, details may change before the project goes to construction.
This page will be updated when final schematics for the project are
151 from Loop 410 to Loop 1604
planning (see timeline below.)
This $80 million project will widen SH 151 from four to six
three lanes each way) with a concrete center barrier. It will also
build a new connector from
151 to northbound Loop 1604 to replace the existing hairpin curve there
and adjust the northbound Loop 1604 exit to Culebra. New turnarounds
will be added at Military Dr., Westover Hills Blvd., and
Wiseman Blvd., a new eastbound
exit ramp to Military Dr. inside Loop 410 will be built, and several
existing right turn lanes at various intersections will be extended and
some new right turn lanes built.
new lanes on SH
151 will be added in the existing grassy median between the eastbound
and westbound lanes. In fact, the median was originally planned for
number of mainlanes shown is the number of through lanes and does not
include auxiliary or transitional lanes.
access road lanes varies depending on location.
purposes only and are not to
project will help
The added lanes are needed to provide capacity for current
traffic volumes in this corridor. Traffic volumes have increased
substantially since the opening of the flyover connectors at Loop
The connector from westbound SH 151 to
northbound Loop 1604 will alleviate
the congestion caused by the
current hairpin ramp there.
The turnarounds will help reduce congestion
in those intersections, especially at Military Dr.
The new ramp to Military Dr. inside Loop 410 will allow that traffic to
bypass the signalized Loop 410 intersections.
modeling of the improvements vs. doing nothing shows a decrease in 2045
travel times of 34% to 60% depending on direction and time of day.
Construction is estimated to start in late 2024 and take about
three years to complete.
problem isn't that there aren't enough lanes on SH 151, it's the
bottleneck at Loop 1604.
That's partially true. First of all, there is indeed a capacity problem
151. For example, traffic backs-up on eastbound SH 151 in the morning.
Since this is headed away from the Loop 1604
interchange, that's obviously not the
cause. Adding the extra lane will help alleviate that congestion.
On the westbound side, yes, the bottleneck at the exit to Loop 1604
northbound is a major
factor in the recurring congestion there during the afternoon rush
hour. The new connector from
westbound SH 151 to northbound Loop 1604 that's planned as part of this
project should resolve that. Even so, traffic volumes headed
westbound now and in the future warrant another lane being
to the corridor. In
fact, since the flyovers at Loop 410 opened, traffic counts in this
corridor have increased substantially.
the backup at Westwood Loop and Alamo Ranch Parkway that
spills back onto SH 151 has been alleviated with the recent completion
of a project to
add an additional westbound through lane at that intersection and will
be further resolved in a few years with the planned
construction of a westbound overpass there. (That is a county project
and is not part of this project.)
- Why didn't they build the
westbound SH 151 connector to northbound Loop 1604 when they
built the other
for that connector at that time. In fact, the flyover that's there now
was not even originally part of the project that built it; it was added
later when additional funding for it became available.
- Why was that hairpin ramp built
ramp was built 20
years ago when the Loop 1604 overpass at Culebra was built and traffic
volumes were substantially less than they are
proximity of the Culebra exit ramp required the entrance
from 151 to be pulled back as far as possible to provide adequate
merging space-- this resulted in the tight ramp that there's now. Given
the low traffic volumes at that time and limited funding, this was
considered to be adequate for the time being. A
"braided" entrance ramp going from the access road over the Culebra
exit was briefly
considered a few years back. However, it was determined that it was not
the best long-term solution and that waiting a little longer to be
able to build the direct connector was the best option.
- Will the endangered spider delay
likely. The spider that caused
the original project to build an underpass for SH 151 under Loop 1604
to be cancelled and re-designed is actually not on the endangered list
anymore. That said, the area is known to be habitat for other
endangered spiders, so TxDOT will have to consult with the US Fish
& Wildlife Department to ensure that approved mitigation plans
in-place. Since this is a known issue this time around, it is
not expected to
significantly delay the project.
the image below to open the detailed schematic for this
project from TxDOT with my own annotations added to help clarify and
explain the various elements. The schematic will
open in a new window that you can scroll and zoom.
schematic is somewhat large and may take a few seconds to