South 10-mile Comprehensive Project


TxDOT is currently working on multiple stand-alone projects between Riverside Drive and SH 45SE, including:

The South10 project would add an express lane in each direction and address all remaining safety and mobility improvements proposed under the Mobility35 Program that were not already included in the above stand-alone projects. Two alternatives are being considered, one express lane build alternative and a no-build alternative. The build alternative includes accommodation for direct transit access to the express lanes.

Need & Purpose
  • Improve safety and mobility for all users of I-35 while minimizing right-of-way, community and environmental impacts
  • Provide a reliable travel time for cars, buses, vanpools and emergency vehicles using the express lanes
Project Description
  • Add a variable tolled express lane and ramp over the mainlanes to the frontage road allowing direct access to downtown Austin (one lane and ramp in each direction)
  • Replace bridge at Slaughter Lane, and widen bridges at Slaughter Creek and Onion Creek
  • Widen frontage roads for auxiliary lanes, or extended entrance/exit lanes, and add turn lanes at Slaughter Lane
  • Add extended entrance/exit lanes on mainlanes
  • Add through-lane to the frontage roads and traffic signal at Onion Creek Parkway
  • Improve bicycle and pedestrian accommodations along frontage roads at east/west crossings
  • Project development funded by TxDOT
  • Construction not funded
  • Construction cost estimate: approximately $300 million to $350 million
  • Finalized schematic and environmental documentation: anticipated winter 2017/2018
  • Begin plans, specifications and estimates (PS&E): anticipated fall 2017
  • Complete PS&E: anticipated summer 2019
  • Construction letting: anticipated summer 2019*
  • Construction start: anticipated winter 2019/2020*
  • Construction completion: anticipated fall 2021*

*Dates are contingent on funding.


Conceptual schematics developed under prior planning activities:

Project Vicinity Map

South Austin Comprehensive Project


Public Information Officer

TxDOT Austin District
P.O. Box 15426
Austin, TX 78761-5426

(512) 832-7000