FLYOVERS FROM US 281 TO LOOP 1604 SET TO OPEN The interchange flyovers from southbound US 281 to both directions of Loop 1604 are scheduled to open this upcoming weekend.

Location
Bandera Rd. (SH 16) from Loop 1604 to Diamond K Trail

Description
This project will convert Bandera Rd. to a superstreet from just outside Loop 1604 to just south of FM 1560 South by converting the intersections at Hausman/Leslie and Cedar Trail to restricted-crossing intersections, adding signalized turnarounds at multiple intermediate locations, and closing the crossover at Diamond K Trail. This project will also construct a new signalized left turn from northbound Bandera Rd. to Legend Trail and will expand the southbound Bandera left turn to Hausman to two lanes.

The restricted-crossing intersections will prevent traffic on Leslie/Hausman and Cedar Trail from going straight or turning left. Instead, all traffic will make a right turn, then use a signalized turnaround about 1000 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 "turning movements diagram" below.

This project will also build an underground storm drainage system and will include sidewalks throughout.

The intersection at FM 1560 South was converted to a superstreet 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 superstreet configuration all the way to Triana Pkwy.

A superstreet is also known by the more technical nomenclature of "restricted crosssing U-turn" (RCUT) intersection.

Click above to see a simplified diagram of the turning movements at each intersection

How this project will help
The Hausman/Leslie intersection experiences significant to severe recurring congestion during both the morning and evening rush hours. By eliminating the through-traffic and left-turns on Leslie/Hausman and Cedar Trail, the green time required for those movements can instead be combined with the left turn green time for traffic turning from Bandera onto those streets. That essentially eliminates the green time needed to service the cross streets, meaning more green time can be allocated to the remaining movements, which therefore moves more traffic through the intersection in the same period of time. This configuration is expected to provide good long-term congestion mitigation based on 20-year traffic projections.

For a further explanation on how a superstreet functions and how it improves traffic flow, see the main superstreets page.

Although it's currently not as congested, converting the Cedar Trail intersection is necessary to provide continuity of improvement. If the Cedar Trail intersection were not also converted, then it would soon become a bottleneck due to the improved throughput on either side of it.

The new left turn at Legend Trail will provide better access to the Stanton Run neighborhood from northbound Bandera Rd. That traffic today must make a U-turn at Cedar Trail and a U-turn at that location will not be possible after the conversion. Since a turnaround for southbound Bandera Rd. was necessary at that location anyway, the left turn to Legend Trail was a sensible addition.

Closing the crossover at Diamond K Trail is necessary as it has become a dangerous crossover location and will be more so in the future, and direct crossovers like this within a superstreet segment negate the improvements afforded by the superstreet. 

• This looks confusing. It will cause lots of crashes.
  This is always one of the first knee-jerk assertions made when an unconventional intersection is introduced. With any change-- even more conventional changes such as new signals or lanes-- it naturally takes drivers a little time to adapt. With a superstreet, because all traffic on the intersecting street is forced to turn right, most confusion is quickly overcome instinctively once the driver has turned or as the driver follows other more experienced drivers through the intersection. Additionally, because all traffic is flowing in the same direction and is protected by signals, the likelihood of collisions is substantially reduced, even during the adjustment period. Superstreets also inherently improve safety by reducing conflict points (the point where vehicle paths cross) by half.
  
  Statistics for superstreets show improved safety. A study for the North Carolina DOT showed that superstreets reduced traffic collisions by 46% and decreased crashes with injuries by 63%. A study of superstreet intersections in Missouri showed a 54% reduction in injury and fatal crashes. Many people predicted mayhem at the Bandera/1604 displaced left-turn intersection, but crashes decreased 44% during the first nine months after it was completed.
  


• How does this crazy design improve traffic? How does adding even more traffic signals help?
  This intersection design improves traffic because, by forcing all traffic on the cross street to turn right, the green time for that can be overlapped with the green time for traffic turning left from Bandera onto the cross street. This essentially eliminates the green time that would needed for the through and left turn movements on the cross street, so that time can then be reallocated to the remaining movements, thus moving more traffic through the intersection in the same amount of time. Although there are extra signals, they are all much more efficient and are better coordinated. See the "How a superstreet works" section of the main superstreets page for a deeper explanation of the superstreet "secret sauce".
  
  
• All they have to do is adjust the signal timing and that will solve the problem.
  It's a common belief that congestion can be solved by simply adjusting the signal timing. In some specific cases, that can be true, but at a very busy intersection like this where there has to be sufficient green time for eight different movements on every cycle, the signals can only be optimized so much before the laws of physics win. For example, the green time on Hausman could be extended to help clear out the peak period backups that occur there, but that means the light will stay red longer for Bandera, which then increases the congestion there. If the green time on Bandera is then increased to ease those backups, that means the light will stay red longer for Hausman and you're right back where you started. So as you can see, it's really not as easy as it sounds.
  
  
• This causes people to have to go out of their way, which is inconvenient and will require more time to get across Bandera Rd.
  Some folks understandably are bothered that to turn left or go straight on the cross street requires going out of one's way to accomplish. This is true and will always be perceived as an inconvenience by many drivers, but because wait times will be shorter and overall congestion in the area reduced, travel time through the intersection should typically be shorter than it would be at a conventional intersection even with the added time necessary to use the turnaround. Also keep in mind that there are many other examples where traffic wanting to make a left turn is prohibited from doing so due to a median, freeway, or one-way street and must therefore turn right first, then make a downstream U-turn or series of left turns, so this situation is not unprecedented or unique to superstreets. In fact, this has already been the case along much of this section of Bandera Rd. due to the existing median.
  
  
• If I'm headed south on FM 1560 (Hausman Rd.) and want to go to Wal-Mart, Starbucks, Bill Miller's, or O'Connor High School, or head southbound on Bandera Rd., how do I get there?
  At Bandera Rd., you'll turn right, travel about 1000 feet to a turnaround (just past Little Caesar's Pizza), then head southbound on Bandera where you can turn right at Bill Miller's, Leslie Rd. (for O'Connor HS), Starbucks, or Wal-Mart, or continue straight on southbound Bandera. To return to Hausman Rd. from Bill Miller's, O'Connor, Starbucks, or Wal-Mart, you'll turn right onto Bandera Rd. and use a turnaround just past Wal-Mart to return to Hausman Rd.
  
  
• Why not build overpasses instead?
  Across the country, traffic engineers have discovered that innovative intersections like this can produce good congestion relief and safety at a fraction of the cost and construction time of flyovers and other traditional grade-separated solutions. This allows the limited transportation dollars to be saved and used for other needed projects.
  
  The current and future traffic volumes and safety considerations along Bandera Rd. aren't sufficient to justify the construction of overpasses or conversion to a freeway, but they are in the "sweet spot" to support a superstreet. Furthermore, the right-of-way along Bandera Rd. is not wide enough for overpasses or a freeway, so the cost would be considerably higher as additional right-of-way would have to be obtained, which likely would result in the displacement of many businesses.
  
  
• Why are there signals to leave the turnarounds?
  This is to prevent slower moving vehicles from entering the faster traffic stream and causing conflicts that could result in collisions or congestion. 
  
  
• Will the Circle A Trail intersection be changed to allow left turns again?
  No, that intersection is outside the scope of this project. 
  
  
• Are there any other superstreets in San Antonio?
  Yes, there have been two superstreet segments in San Antonio. One is on US 281 north of Loop 1604 and the other was nearby on Loop 1604 between Braun Rd. and Culebra Rd. Both were built as short-term solutions while funding for freeway expansions was obtained. The Loop 1604 superstreet was replaced by a freeway in 2016, and the US 281 superstreet will be replaced by a freeway in the next year or so. Unlike the 281 and 1604 superstreets, the superstreet in Helotes is considered a long-term solution. A superstreet was also considered for Bandera Rd. inside Loop 1604, but has been tabled while a new corridor study is conducted.
  
  
• Who came up with this cockamamie design? This won't work and is just a waste of money.
  The superstreet design has been used in several US states for the past couple of decades and has a proven track record of improving traffic wherever it has been implemented. Both the US 281 and Loop 1604 superstreets showed appreciable improvments, and computer modeling shows that this superstreet will do the same. A superstreet is one of several types of "innovative" or "alternative" intersection designs being implemented across the country at intersections where improvements from conventional expansions will be short-lived but where conditions do not warrant more expensive traditional upgrades such as flyovers. Many people expressed similar doubts about the nearby Bandera/1604 DLT intersection, but the new design has substantially reduced congestion and crashes there.
  

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. 

DETAILED PROJECT SCHEMATIC

Click above to see the detailed annotated schematic for this project

	TxDOT - Virtual Public Meeting - SH 16 Helotes https://www.txdot.gov/inside-txdot/get-involved/about/hearings-meetings/san-antonio/063020.html
	TxDOT - SH 16 Helotes Proposed Roadway Improvement video https://www.youtube.com/watch?v=sY97-816VAY&feature=youtu.be
	Pape-Dawson "Superstreets in Texas" presentation https://drive.google.com/file/d/16b1w_qy_D8A2U_ZWhkG8jtkPZFqcNXlm/view
	Wikipedia - Superstreet https://en.wikipedia.org/wiki/Superstreet
	Federal Highway Administration - Restricted Crossing U-Turn Intersection Informational Guide https://safety.fhwa.dot.gov/intersection/alter_design/pdf/fhwasa14070_rcut_infoguide.pdf
	An Update on Superstreet Implementation and Research http://www.accessmanagement.info/AM08/AM0807Hummer/AM0807Hummer.pdf
	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