The Texas
Highway Man

Home Search Miscellany Updates About me Contact Menu
Other San Antonio Area Roads
PROJECT INFO: Bandera Rd. RCUTs (Helotes)

This page last updated June 19, 2024

Project location map
Project location map Location
  • Bandera Rd. (SH 16) from Legend Trail to Diamond K Trail

Status
  • Under construction (87% complete)
  • Intersection at Legend Trail opened on 5/22/2024

Timeline
  • Construction began in August 2022 and is projected to be complete in mid 2024.


ADVERTISEMENT




On this page:


Summary

Here is a brief "PowerPoint" summary of this project:


Project description

This project is converting the intersections on Bandera Rd. at Hausman Rd./Leslie Rd. and Cedar Trail to "Restricted Crossing U‑turn" (RCUT) intersections, adding signalized turnarounds at multiple intermediate locations, and closing the crossover at Diamond K Trail. It has also constructed a new signalized left turn from northbound Bandera Rd. to Legend Trail, will expand the southbound Bandera left turn to Hausman to two lanes, and will widen Bandera to three lanes in each direction between Hausman/Leslie and Circle A Trail.

The RCUT intersections prevent traffic on Leslie/Hausman and Cedar Trail from going straight or turning left. Instead, all traffic must make a right turn, then use a signalized turnaround about 1,000 feet downstream to make a U‑turn and continue in the intended direction of travel. Left turns from Bandera Rd. to those cross streets will still be allowed. To better visualize this, click on the following diagram.

Left turn schematic

Click above to see a simplified diagram of how drivers will make a left turn at each intersection
(Base image from TxDOT; annotations by Brian Purcell)

This project also built an underground storm drainage system and is adding sidewalks throughout.

The intersection at FM 1560 South was converted to an RCUT configuration in 2018, and the intersection at Loop 1604 was converted to a displaced left turn (DLT) in 2019, so this will close the gap between these two improved intersections and complete the master plan for this section of Bandera Rd. TxDOT plans to eventually continue the RCUT configuration all the way to Triana Pkwy. as traffic warrants.

An RCUT intersection is also known as a "superstreet".

Typical RCUT intersection diagram

Typical RCUT intersection
(Base graphic from Wikipedia modified by Brian Purcell)

Circle A Trail intersection
With the previous project to realign the FM 1560 South intersection, the intersection at Circle A Trail was changed to a signalized right-in/right-out configuration (i.e. no left turns or crossovers.) This was done to streamline traffic operations in the area as that intersection is fairly close to the new FM 1560 intersection and is between it and the southbound-to-northbound turnaround. This has understandably caused some consternation and grousing among residents of Helotes Park Estates who are now required to make a right turn and proceed to a turnaround about ¼ of a mile away in order to go south on Bandera, adding about ½ mile to their trip. (Some conspiracy-minded residents even absurdly assert that this configuration is retaliatory in some way.)

Based on resident feedback as part of the planning for the this project, TxDOT asked their engineering consultant to re-evaluate the Circle A Trail intersection to determine if it would be feasible to allow left turns from Circle A to southbound Bandera. While still physically possible, the analysis showed that doing so would be problematic from an overall operational standpoint. With the RCUT intersections, the signals in each direction of the corridor operate independently and therefore can be better timed for the respective traffic volumes, thus resulting in better overall traffic flow and fewer delays for all directions of travel. Converting the Circle A intersection to allow left turns would require the signals for northbound and southbound Bandera at that location to return to interdependent operation, thus complicating the coordination of the signals in one or both directions of the remainder of the corridor. This would nullify the benefits of the RCUTs and result in this intersection becoming a new bottleneck, the significance of which would increase over time as traffic in the corridor increases.

There were also safety issues with reintroducing left turn cross traffic conflicts at one location in a corridor that otherwise will not have any. The negative impacts to the overall corridor operation and safety were significant enough to outweigh the benefits for the relatively small volume of traffic from Circle A Trail.

It's worth noting that reducing congestion along Bandera benefits the residents of Helotes Park Estates and should reduce their overall travel time in the corridor even with the additional travel time required to execute the right-turn and U‑turn, and that there are many other locations where drivers are required to go a little out of their way for the benefit of overall efficiency and safety, including some long-time existing locations nearby along Bandera Rd.


How this project will help

The Bandera Rd. - Hausman Rd./Leslie Rd. intersection experiences significant to severe recurring congestion during both the morning and evening rush hours and is the main choke point on Bandera outside Loop 1604. Converting the intersection to an RCUT will increase the throughput of the intersection significantly and reduce wait times and delays correspondingly in this section of the corridor.

How an RCUT increases intersection throughput
Forcing traffic on the cross street (Hausman/Leslie and Cedar Trail) to turn right allows that traffic to be overlapped with the corresponding left turn from Bandera and eliminates the need for green time for the left turn and straight-through movements from the cross streets. The green time that would have been needed for those movements can instead be allocated to the remaining movements, which therefore will allow more traffic through the intersection in the same period of time, thus significantly reducing wait times and congestion. See the example signal timings below to get an idea of how an RCUT allows green time to be redistributed.

Ah ha!

If all of that sounds like technical gibberish, here's another way of explaining it:

At a traditional intersection, drivers who arrive as the light turns red have to wait for three or four other directions to get a green light before their light turns green again. At an RCUT intersection, drivers only have to wait for one signal change before they get a green again. Drivers then needing to use the turnaround may have to subsequently wait for one more signal change, but that's still less than before.

Additionally, with an RCUT, each half of the intersection operates independently of the other, so the signals along each direction of Bandera Rd. can be timed separately from the other direction, which means better coordination and synchronization are possible.

Modeling showed that this configuration is expected to provide good long-term congestion relief based on 20-year traffic projections.

Example Bandera Rd. - Hausman Rd./Leslie Rd. signal timings

  • The whole pie below represents the time for a full signal cycle (~150 seconds.)
  • The pieces of the pie show the proportion of green time each movement gets during each cycle.
  • Blue sections represent Bandera Rd. traffic.
  • With an RCUT, all the movements except the through movements on Bandera get combined, and, in this example, are combined into the biggest piece of the pie from the conventional intersection. After doing so, that slice can (and probably will) be increased as needed to better accommodate Hausman/Leslie traffic, and even after doing so, everyone still gets more green time than they had in the conventional intersection.
  • Timing splits are approximate as they change during the day, but are typical.
  • Timings were obtained by yours truly by monitoring the intersection for three half-hour periods during a Wednesday in April 2022.
  • Finally, in an RCUT, the signals on each side of Bandera Rd. can be timed independently of the other, and thus would be two separate pies, so the RCUT chart below combines both directions for simplicity.
Previous (conventional)
Current signal phasing pie chart
RCUT*
RCUT signal phasing pie chart

Blue sections represent Bandera Rd. traffic
The other sections represent the other intersection movements relative to Bandera Rd.

* The orange slice in the RCUT used the largest orange slice from the conventional intersection and can be increased if needed. Read the fourth point in the explanation above for more details.


SH 16 RCUT sign

For a deeper dive on how an RCUT functions and how it improves traffic flow, see the main Restricted Crossing U‑turn intersections page.

Cedar Trail intersection
Although it's currently not as congested, converting the Cedar Trail intersection was necessary to provide continuity of improvement. If the Cedar Trail intersection were not also converted, then it would soon become a bottleneck as its conventional signal cycle would not be congruous with the improved throughput at intersections upstream in both directions.

Legend Trail intersection
The new left turn at Legend Trail provides direct access to the Stanton Run neighborhood from northbound Bandera Rd. Previously, that traffic had to make a U‑turn at Cedar Trail which will be prohibited after the conversion. Since a turnaround for southbound Bandera Rd. was necessary at Legend Trail anyway, the left turn to Legend Trail was a sensible addition. The new signal it introduces for southbound Bandera will be integrated into the overall signal coordination afforded by the upstream RCUTs.

Diamond K Trail intersection
Closing the crossover at Diamond K Trail was necessary as it had become an increasingly dangerous intersection and would be more so in the future, and direct crossovers like this within an RCUT segment negate the safety and congestion improvements the RCUTs provide.


FAQ


Schematic

Click on 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 thumbnail

Click the image above for a full-sized schematic of this project


Video

TxDOT has a good video that describes this project:





Other sites of interest

TxDOT - Virtual Public Meeting - SH 16 Helotes
https://www.txdot.gov/projects/hearings-meetings/san-antonio/archive/063020.html
Pape-Dawson "Superstreets in Texas" presentation
https://drive.google.com/file/d/16b1w_qy_D8A2U_ZWhkG8jtkPZFqcNXlm/view
NC Department of Transportation presentation on superstreets
(Excellent explanation of all aspects of superstreets)
https://www.partnc.org/DocumentCenter/View/331/NCDOT-Superstreet-Presentation-PDF
Wikipedia - Superstreet
https://en.wikipedia.org/wiki/Superstreet
Virginia Department of Transportation - Restricted Crossing U‑turn
https://www.vdot.virginia.gov/about/our-system/highwaysinnovative-intersections/restricted-crossing-u-turn/
Federal Highway Administration - Restricted Crossing U‑turn Intersection Informational Guide
https://safety.fhwa.dot.gov/intersection/rltci/fhwasa14040.pdf/
An Update on Superstreet Implementation and Research
http://www.teachamerica.com/accessmanagement.info/AM08/AM0807Hummer/AM0807Hummer.pdf