Work is anticipated to begin in late 2010 on the first half of a long-planned and equally long-awaited US 281/Loop 1604 directional interchange.  This project will construct the four southern elevated connectors: US 281 northbound to both directions of Loop 1604 and both directions of Loop 1604 to US 281 southbound.  The remaining ramps will not be built until the future of US 281 north of Loop 1604 is finalized.

In addition to the four connectors, this project will also make several ancillary improvements to both US 281 and Loop 1604 in the vicinity.

This project is being developed and managed by the Alamo Regional Mobility Authority (ARMA).  Funding for the project is coming mostly from the federal "stimulus" program.

Approximately 250,000 vehicles per day pass through the interchange on US 281 and Loop 1604 with about 20% of them making connections between the two.

This will be the first five-level interchange in San Antonio.

On this page:

• Details
• Status
• Project history
• Other sites of interest

Details

The map below shows the overall scope of the project.  As you can see, it extends well beyond the actual 281/1604 crossing.  Click on a letter on the map for a close-up schematic of that section.  Each of the images is over 600KB and will open in a new browser window.  These schematics are preliminary and are subject to change.  On the schematics, roads outlined in red are mainlanes, green are frontage roads, yellow are entrance/exit ramps, and gold are the new elevated connectors.  I plan to annotate the schematics in the near future to help in better deciphering them.

Click on a letter above to see detailed plans for that section.
(Schematics courtesy of ARMA)

This will be a five-level interchange:

• Level 1 (bottom): US 281 mainlanes
• Level 2: US 281 and Loop 1604 frontage roads
• Level 3: Loop 1604 mainlanes
• Level 4: Connectors from US 281 to Loop 1604
• Level 5: Connectors from Loop 1604 to US 281

In addition to the interchange ramps, a number of other ancillary improvements are also proposed for both US 281 and Loop 1604:

• Northbound US 281:
  • The existing exit ramp to Loop 1604/Henderson Pass will be removed to make room for the new exit to Loop 1604.  Motorists wanting to access Henderson Pass and the US 281 frontage road in that area will use the existing Donella Dr. exit instead.
  • An auxiliary lane will be added between the existing entrance ramp from Bitters Rd. and the existing exit ramp to Thousand Oaks Dr.
  • An auxiliary lane will be added between the existing entrance ramp from Brookhollow Dr. and the existing exit ramp to Donella Dr.
• Southbound US 281:
  • The existing entrance ramp from Loop 1604 (just north of Henderson Pass) will be removed to make room for the new connector entrance from Loop 1604.  Motorists on the US 281 frontage road wanting to enter US 281 will continue south and use the existing entrance ramp south of Donella Dr.
  • An auxiliary lane will be added between the existing entrance ramp from Thousand Oaks Dr. and the existing exit ramp to Bitters Rd.
• Eastbound Loop 1604:
  • The existing exit ramp to US 281 will be moved back to just beyond the Stone Oak Pkwy. overpass to make room for the new exit to US 281.
  • A new exit for Redland Rd. is planned just east of Mud Creek.
• Westbound Loop 1604:
  • The existing exit ramp to Gold Canyon Rd. will be removed to reduce mainlane weaving on the approach to the US 281 exit.  Motorists wanting to access Gold Canyon or the 1604 frontage road would use the existing Redland Rd. exit instead.
  • The existing entrance and exit ramps between Stone Oak Pkwy. and Blanco Rd. will be reversed to better facilitate the new auxiliary lane and traffic entering from US 281.
  • An auxiliary lane will be added between the existing Blanco Rd. entrance ramp and the existing Bitters exit ramp.
     
• Auxiliary lanes would also be added to the frontage roads in several locations.
• Turnarounds will be added at the following overpasses on Loop 1604: Bitters Rd., Huebner Rd., Gold Canyon Rd., and Redland Rd.
• Continuous nighttime illumination will be added to Loop 1604 throughout the project area as well as on the new connectors.
• Sidewalks will be added to the frontage roads through much of the project area.
• Two pedestrian overpasses will be constructed over US 281 at Loop 1604 (one on each side running parallel to the Loop 1604 frontage roads.
• The Henderson Pass overpass, which has been closed since the mid '90s, will be mostly torn-down.  A small section for utilities will remain.

Renderings

The following are renderings of the proposed complete interchange that were part of computer simulations for the US 281 and Loop 1604 tollway projects.  Please understand that these renderings are provided for conceptual purposes only and that details shown in them may not represent the latest proposals for the interchange.  Also, keep in mind that only the four southern ramps will be built in this project.
 

View looking northbound over US 281

View looking eastbound over Loop 1604

Additional renderings and animations are available on ARMA's US 281/Loop 1604 Interchange project page.  (See the links section below.)

Status

Construction is projected to begin in late 2010.

Project history

In the late '80s, US 281 from Bitters Rd. to today's Sonterra Blvd. was upgraded from a four-lane divided highway to the current six-lane expressway.  That project added the existing three-level interchange at Loop 1604.  Limited funding at that time precluded a larger interchange and the three-level configuration was determined to be adequate for the existing and projected short-term traffic volumes.

By the mid to late '90s, TxDOT planners were beginning to evaluate various improvements to the interchange, including a variation of a Single-Point Urban Interchange (SPUI) which would have built two X-shaped bridges through the middle of the existing interchange to expedite left turn movements thus allowing for longer green times in all directions.  Because of funding constraints, that project was never built.

At a public meeting in 2000 for proposed improvements to US 281 at and north of Loop 1604, handouts included an artist's rendering of a proposed five-level interchange at Loop 1604.  At that time, it was listed as a long-term project (beyond FY 2004).  Those plans formed the basis for the current plans.

Circa 2005, with funding becoming even more limited, the interchange project was transferred to ARMA and rolled into the mega Loop 1604 tollway project.  The connectors were proposed to be connected to the tolled "managed" lanes in the center median of Loop 1604 and use of the connectors themselves would be tolled.  Renderings of both the Loop 1604 and US 281 tollway projects showed the interchange in this configuration.  (Those renderings are in the "Details" section above.)

In February 2009, Congress approved a national economic "stimulus" plan that would pour additional federal money into road construction projects.  The Metropolitan Planning Organization (MPO) approved allocating San Antonio's share of transportation stimulus funding to be used as matching funds to leverage state funding for the first half of a 281/1604 interchange.  This project would build all four of the ramps connecting to 281 south of 1604, i.e. northbound 281 to both directions of 1604, and both directions of 1604 to southbound 281.  It was determined that ramps connecting to 281 north of 1604 could not be built until lingering issues stemming from the lawsuits and associated environmental studies for 281 north of 1604 are resolved.  Although the entire interchange had been previously proposed as a toll-project, the use of the federal funds will allow the ramps to be toll-free.  The Texas Transportation Commission (TTC) approved the funding request on March 5th, 2009, and construction is expected to begin in late 2010.

On March 13th, 2009, it was reported that opponents to the 281 North toll project were considering a legal challenge to the 281/1604 interchange on the grounds that it should be subject to a new environmental review as part of the entire Loop 1604 and US 281 studies.  However, as of the end of 2009, no lawsuits had been filed.  Environmentalists again hinted in late April 2010 that they might sue to stop the interchange unless sufficient measures were taken to protect endangered species in the vicinity.

Other sites of interest

Alamo Regional Mobility Authority - US 281/Loop 1604 Interchange project page http://www.alamorma.org/US281Loop1604Interchange.html