A faster, safer and smarter mode to access Austin and destinations north and south.

Texas’ capital features an array of moving parts that make it uniquely Austin. Legislators, students, residents and visitors all converge downtown, vying for access to the capitol, central business district, University of Texas, and world-famous entertainment venues. Much of the activity in this fast-growing city spills onto Interstate Highway 35 just south of downtown, creating traffic jams on a vital economic corridor. 

Truckers experience delays going south toward San Antonio and Mexico and north through the heart of Texas and the Midwest toward Canada. Adding to the high traffic volumes, I-35 serves as Austin’s only non-toll road of the three major north-south corridors. Eighty crashes were reported on the 3.2-mile stretch between Stassney Lane and William Cannon Drive from 2010 to 2015 — this segment has a 30% higher crash rate than the state average for urban interstates. 

The I-35 Stassney Lane to William Cannon Drive project was designed to mend interstate travel. HDR provided construction engineering inspection services to the Texas Department of Transportation, Austin District, with a focus on safety. 

We inspected contractor activities with an emphasis on keeping I-35 open to motorists. Improvements include: 

• Adding new U-turn bridges at Stassney Lane and William Cannon Drive in both directions — reducing vehicle queue lengths at intersections. The U-turn bridges improve access to driveways and cross streets and reduce left-turn volumes at signalized intersections by 20%.
• Widening the I-35 main lanes — incorporating shoulders for vehicle use during emergencies.
• Extending entrance/exit lane ramps — allowing for better merging by mitigating speed discrepancy between ramp and main lane traffic.
• Adding an extra lane to frontage roads — improving access to businesses and ramps and reducing overall congestion.
• Reconstructing the bridge structures at Stassney Lane and William Cannon Drive, as well as the frontage road bridge over Williamson Creek — improving vertical clearance and flood safety.
• Adding a shared-use path for bicycles and pedestrian — improving access for these modes.  
• Installing lighting and drainage features — improving safety and reducing the amount of discharge into streams. 

TxDOT hired us in 2016 with a detailed scope that comprised: inspecting structures, including foundations, substructures and superstructures; concrete and hot-mix asphalt paving, including the subgrade up to the pavement; stormwater pollution prevention plan elements; and additional transportation components, including items listed in TxDOT specifications. 

We observed bridge columns, bent caps and decks; retaining walls; and soil nail walls. We also provided strategic communications services. 

One of the team’s most successful outreach campaigns took place in advance of a night closure for bridge beam installation. Three main lanes closed for five hours, detouring traffic to the frontage road. Because of early communication, 2,954 fewer vehicles (38% less) traveled through the project site during critical construction activities. 

With Austin’s vibrant downtown and continually growing population, I-35 needs persistent improvement to reduce bottlenecks and accidents.