Antonio Area Freeway System
INFO: US 281 at Basse
page last updated December 8, 2018
As this project is currently in planning, all information is
preliminary and subject to change.
Location: US 281 at Basse Road
planning (see timeline below)
This approximately $7 million project will make improvements
to the US 281/Basse Road interchange. The existing cloverleaf ramps
from westbound Basse to southbound US 281 and from northbound US 281 to
westbound Basse will be removed. They will be replaced with an exit
ramp from southbound US 281 and an entrance ramp to northbound US 281.
The exisiting entrance ramp to southbound US 281 from eastbound Basse
will be re-aligned to provide access from both directions of Basse via
a new signalized intersection. Another new signalized intersection at
the remaining existing northbound exit ramp will facilitate left turns
onto westbound Basse from US 281.
wanting to enter northbound US 281 from eastbound Basse will utilize
a displaced left-turn (DLT) lane. This means that traffic
making that turn will cross over to the other side of Basse Road well
in advance of the location of the entrance ramp (in this case, the
crossover will be at the location of the southbound entrance ramp.) The
crossover will be signalized. They will then travel in a
median-separated contraflow lane to the left of westbound Basse
traffic, pass through the intersection with the new southbound exit
ramp, continue under US 281, and directly enter the new northbound
entrance ramp. (Yes, this probably sounds confusing, so see the diagram
and schematic below to better understand it.)
DLT configuration will also slightly change how traffic from the new
southbound exit ramp turns right onto westbound Basse. Instead of
turning directly onto the Basse mainlanes at the intersection, they
will instead travel a short distance in a barrier-separated lane
alongside the contraflow lane described above, then merge into Basse
Road. This allows that traffic to avoid all conflicts in the
interchange. (Again, see the diagram below for clarification.)
A companion project to improve traffic flow is planned at Jones-Maltsberger.
FLOW FOR EASTBOUND BASSE TO NORTHBOUND US 281
AND SOUTHBOUND US 281 to WESTBOUND BASSE
to NB US 281 is shown in red
SB US 281 to WB Basse is shown in yellow
Black arrows are regular mainlane traffic flow on Basse
project will help
Adding the new exit and entrance ramps will allow traffic
that currently has to use the Jones-Maltsberger interchange to instead
use this interchange. This should help to reduce congestion at the
Jones-Maltsberger interchange as well as on Jones-Maltsberger and Basse
in the vicinity of the Alamo Quarry Market.
the DLT configuration will help this intersection operate more
efficiently for the long-term. Shifting that left-turning traffic out
of the way of opposing traffic reduces the number of signal phases
required, thus allowing the intersection to move more traffic per
signal cycle. Since it is anticipated that the westbound Basse to
southbound US 281 movement will be quite heavy, shifting the
opposing left turn movement out of the way will provide an especially
significant improvement over a conventional intersection at this
location. See the Bandera
and 1604 DLT project page for more information about the
benefits of a DLT.
is not yet scheduled. As of this writing, it is anticipated that work
could begin in 2021 and take about a year to complete.
- This looks confusing.
It will cause lots of crashes.
While it may look complicated on the schematics, it's
actually fairly easy to navigate on the ground. See the
"how-to" video at the bottom of this page. Statistics from DLT
implementations show a significant reduction in crashes and
practical experience from other DLT locations shows drivers quickly
adapt to it.
- How does this improve
new ramps will allow another access point onto northbound 281 and
another exit from southbound 281 in this area. Today, all traffic
wanting to make those maneuvers have to use the Jones-Maltsberger
interchange. This adds congestion to that interchange as well as to
Jones-Maltsberger and Basse Road in between. Making this interchange
accessible from all directions should help to alleviate that congestion.
DLT component of this intersection design will help keep this
intersection operating efficiently because shifting the eastbound
to the left side of the road through the interchange removes the
conflicts between that left turn and opposing traffic that you would
have in a
conventional intersection. As a
result, traffic in two of the four legs of the intersection can move
during a single green phase instead of needing two separate
phases, thus moving more traffic through the intersection in the same
amount of time.
- Will there be
No, this project will not add turnarounds. There is insufficient demand
at this location for turnarounds.
- How is this different than the
intersection under construction at Bandera and Loop 1604?
This is the same concept as the intersection being built at Bandera
However, in this case, this is only a partial DLT;
specifically, only a half DLT. (There is a similar partial DLT in
operation in San Marcos on Aquarena Springs Drive at I-35.) Also, the
Bandera/1604 intersection (as well as the San Marcos
location) facilitates straight-through traffic on the access
roads; that's not
- Who came up with this cockamamie
Most of this
new intersection is a conventional "diamond" interchange in use around
the world. The DLT design has been around for several decades
and is in use in
several dozen locations in the US and internationally and has a proven
track record of improving traffic wherever it has been implemented. It
is one of several types of "innovative" or "alternative" intersection
designs being implemented across the country at intersections
not warrant more expensive conventional upgrades (e.g.
flyovers.) Because of the heavy westbound to southbound turning
movement expected here, the DLT will help this intersection operate
efficiently for the long-term.
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. Below
a "how-to" video on making a
left turn at a DLT .
DETAILED PROJECT SCHEMATIC
video of how to drive through a DLT, see
sites of interest