SL 360 is a major transportation corridor for the Austin area, acting as a thoroughfare and commuter route for residents in west Austin as well as those passing through. The 14-mile corridor runs from US 183 on the north end to US 290/SH 71 on the south end. Loop 360 suffers severe traffic congestion, causing both mobility and safety concerns. TxDOT expects traffic congestion to increase as their population grows. More than two million people live in the Austin area when this project began in 2018, and that number is expected to double by 2040.
The Loop 360 program upgrades nine intersections along SL360 to be grade-separated. These improvements will provide substantial benefits for congestion relief. Aguirre & Fields is responsible for designing all roadway and structural elements from south of Greet Hills Trail to south of Champion Grandview Way, including the intersections and improvements at Spicewood Springs and Lakewood Drive.
The Spicewood Springs intersection crosses into Jollyville Plateau Salamander habitat. In order to minimize impacts and avoid the lengthy process of obtaining an Incidental Take Permit from US Fish & Wildlife, Aguirre & Fields proposed mountable curb and gutter along the mainlanes and ramps within the habitat, captured all runoff in a closed storm drain system, and discharged the runoff downstream of the habitat.
The Lakewood Drive intersection includes a 5′ diameter historic oak tree that fell within the proposed southbound frontage road pavement along the existing as-built centerline. In response to several comments received during public involvement meetings indicating a desire to save the tree, Aguirre & Fields proposed realigning the existing as-built centerline and reconfiguring the proposed typical section to achieve the required clearance to save the tree.