Proposed Elevated Structures

To bypass the intersections and signals at William Cannon Drive and SH 71, both Alternatives A and C propose sections of elevated mainlanes in the US 290 corridor. Out of the eight miles of proposed roadway, US 290 will be elevated for one half-mile for Alternative A, and one mile for Alternative C. The elevated direct connection from US 290 to SH 71 will keep commuter traffic off local roads, easing up access for local business and neighborhoods.

To meet the purpose and need of the project, and due to the large volume of traffic on US 290, no option where the frontage roads and mainlanes were at the same level could meet the mobility and safety demand. Signalized intersections are not a long term mobility solution when traffic volumes are as high as these on US 290 and SH 71.

The elevated structures would be an average height of 25 feet with a maximum height of approximately 37 feet above the existing ground, about the height of a two story house. You can see our artistic renderings of these elevated structures by viewing our new renderings page.

Consider this:

 

  • The highest proposed bridge structure on the project is shorter than the Austin Pizza Garden building on US 290 near Patton Ranch Road.
  • The structures are also shorter than the highest point of the bluff and the power lines along US 290.
  • These would be very similar to the height of the US 290 overpass at Old Fredericksburg Road.

The floodplain is a large expanse through the US 290 Corridor and a major constraint for how feasible alternatives facilitate mobility.

Part of the project area lies within a 100-year flood zone. In order to minimize impacts to the floodplain and to provide a reliable transportation corridor during a major flood event, the mainlanes would need to be built above the floodplain elevation.

Additionally, elevating the US 290 mainlanes over William Cannon Drive avoids impacts to several large oak trees and Edwards Aquifer recharge features in that location.

Is it true that Williamson Creek will be located between two proposed elevated structures?

Yes, if the proposed project is approved, a short length of Williamson Creek will be located between two portions of the project. A proposed shared use path for bicyclists and pedestrians is planned along that stretch of the creek to allow the community better access and enjoyment of the area.

We can address the look and feel of how the elevated structures and park-like enhancements look through the Context Sensitive Solutions process. This public outreach-focused process will result in ideas and concepts for aesthetics, bicycle/pedestrian opportunities, and landscaping enhancements in this location. Learn more about this process by clicking here.

Safety and mobility is another key issue.

The proposed direct connectors at the interchange of US 290 and SH 71 are needed to safely handle the turning movements between the two highways. The mainlanes of US 290 will need to be at a different level from the frontage road turning lanes between SH 71 as well. Alternative A proposes depressing the US 290 mainlanes under the SH 71 frontage road turning lanes, while Alternative C would elevate the US 290 mainlanes over the SH 71 frontage road turning lanes.

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Austin, TX 78761-5426