The Texas Department of Transportation is about a year away from beginning construction on a $300 million project to add two high-occupancy vehicle, or HOV, lanes in each direction along I-35 in South Austin from SH 71 to SH 45 SE.
The added nontolled lanes on this roughly 8-mile stretch of road would be used by public transportation, emergency vehicles, carpools and vanpools. In addition, TxDOT plans to add approximately 13 miles of shared-use bicycle and pedestrian paths along the route and reconstruct bridges in an effort to make the highway safer and help traffic move through the corridor more easily.
This is a long-planned project that held an in-person open house in 2019 and a virtual public meeting in December 2020. TxDOT has once again opened its official public comment period at another virtual public hearing open now through May 26. Residents can submit comments here, email CapExSouth@txdot.gov, leave a comment by voicemail at 512-501-5451 or write to I-35 Capital Express South Project, Attn: Matthew Cho, P.E., 1608 W. Sixth St., Austin, TX, 78703.
According to the most recent designs TxDOT has included in its presentation, the HOV lanes would be elevated above the rest of the vehicles through a roughly 2.5-mile stretch between SH 71 and Slaughter Lane
A report TxDOT commissioned by the University of Texas at Austin Center for Transportation Research found that elevating the managed lanes in this stretch would lead to a 55% decrease in conflict points—areas where drivers are more likely to get in a crash such as highway entrances, exits and weaving points. Researchers also predicted a 29% decrease in severe crashes per year from the historical average of 80 in this stretch of highway.
TxDOT expects a final environmental decision this summer, a necessary step under federal law before the final design is reached and construction can begin—both of those steps are expected next year.
The project is one of three in Austin that would add HOV lanes—the others would take place in central and north Austin, and the projects have a combined value of $5.6 billion. While the south project would elevate the managed lanes, initial designs from TxDOT show the $4.9 billion Central Austin project would take down the upper decks.
Diann Hodges, a spokesperson for TxDOT, said via email both proposals are about safety and making sure drivers do not have to cross managed lanes in order to get from frontage roads to the managed lanes. In the Central Austin project, removing the decks would allow drivers to exit the HOV lanes through a tunnel system or at ramps in strategic locations. In the South Austin project, the elevated lanes would allow TxDOT to add shoulders and reduce conflict points.
"In terms of safety cost benefits, the elevated section would save approximately $21 million per year," Hodges wrote.