Traffic congestion, particularly on I-35, has commonly been referred to as the Central Texas region’s Achilles’ heel and the elephant in the room.

But with the Texas Department of Transportation beginning to implement its $4.3 billion Mobility35 plan in Hays, Travis and Williamson counties that could change.

“This is not some far-off, distant plan,” said Jeremy Martin, senior vice president of regional infrastructure for the Greater Austin Chamber of Commerce. “There are projects ready to go today that are funded today.”

Because TxDOT would not be able to fund the entire $4.3 billion plan at once, it divided the plan into segments, I-35/Mobility35 Program Manager Karen Lorenzini said.

One of the first projects in the Mobility35 plan scheduled for construction in 2016 is improvements to the bridges at William Cannon Drive and Stassney Lane. That project and three others are funded through Proposition 1, which voters approved in November and diverts a portion of the state’s oil and gas tax revenues to the State Highway Fund.

“Prop. 1 is really what gave this current planning effort the real jump-start,” Lorenzini said. “… That really turned it from a planning effort into an implementation effort.”

Other projects heading into an environmental review include depressing the main lanes at 15th Street, adding a third lane to the upper decks, and either modifying the existing main lane configuration between Eighth and Cesar Chavez streets or depressing the lanes.

For years TxDOT officials said adding the additional lane on the upper decks was not feasible. However, a final review of the decks and supports revealed with reinforcement of both the support structures and columns a third lane would be possible.

State Sen. Kirk Watson, D-Austin, announced the upper deck and 15th Street improvements during a June 15 chamber event and said they will provide more capacity and relieve the worst of the I-35 bottleneck during peak periods.

“This is a major improvement for the neighbors, the university, the medical school, Central Health and the Capitol Complex, not to mention the commuters on foot, bike and in their cars,” he said.

TxDOT would construct the third lane on the upper decks at the same time as construction of the express lanes—similar to the toll lanes under construction on MoPac—it plans to add in either direction in Travis County, Lorenzini said. Construction on any of the other projects could occur as funding becomes available.

“These projects we are saying we could implement,” she said. “They have immediate improvement for auto, trucks, transit, [bicyclists and] pedestrians without a toll component. If the toll projects are never built these projects offer [stand-alone] benefit.”

To provide aid during construction TxDOT will use electronic signage to alert drivers of travel times before entering a construction zone. This would allow drivers to choose other options such as MoPac, SH 130 or the Bergstrom Expressway, which the Central Texas Regional Mobility Authority anticipates opening in 2020 before the I-35 projects between US 183 and Ben White Boulevard are built. The Bergstrom Expressway will include construction of six toll lanes and six nontolled lanes between Hwy. 290 and Hwy. 71.

Lorenzini said TxDOT is seeking to fund construction of direct connections from northbound US 183 to northbound I-35 and southbound I-35 to southbound US 183. TxDOT’s goal is to time the opening with the Bergstrom Expressway.

“There are lots of people who would like to be able to get to [Austin-Bergstrom International Airport] from north and other destinations to use those,” she said.

TxDOT officials have repeatedly said the organization’s funding for maintaining the state highway system is about $5 billion short annually. Watson said Prop. 1 helps bridge that gap as well as the Texas Legislature ending the diversion of gas tax revenue from transportation, which is estimated to bring in another $600 million annually.

More TxDOT funding could become available if voters approve a constitutional amendment in November. Approval would divert to the SHF $2.5 billion from the state’s sales tax after revenue exceeds $28 billion annually.

“The funding puzzle is not completely solved … ,” Watson said. “One of the things I’ve been pushing hard is [to] get this 10-year plan in place so that we’re ready any time money is available.”