Construction on the first underpass in Central Texas, a part of the new MoPac express toll lane, is nearly complete.

Steve Pustelnyk, director of community relations for the Central Texas Regional Mobility Authority, said the underpass is projected to open in September, along with the rest of the MoPac express lane.

The MoPac Improvement Project is adding a northbound and southbound express toll lane between Parmer Lane and Lady Bird Lake.

The southbound underpass will exit from the MoPac express lane onto Cesar Chavez Street and Fifth Street in Austin, and drivers access the northbound underpass onto the MoPac express lane from Cesar Chavez Street only, Pustelnyk said.

This month, other milestones in the MoPac Improvement Project include the widening of the FM 2222 northbound exit ramp to two lanes and the construction of a communication duct along MoPac from 45th Street to Enfield Road.

Pustelnyk said the communication duct is a collection of underground plastic tubes running alongside MoPac. The tubes contain fiber-optic cables that transmit data like toll transaction information, traffic volumes and camera images.

Pustelnyk also said final friction course paving on MoPac southbound from US 183 to FM 2222 is underway.

“Once they’re done with that—and that looks to be done by the end of next week—they’re going to shift that over to the northbound section of work,” he said.

Reporting contributed by Amy Denney/Community Impact Newspaper.

Disclosure: Amy Ellsworth, general manager for Community Impact Newspaper’s Round Rock-Pflugerville-Hutto edition, was appointed in February to the Central Texas Regional Mobility Authority board of directors to serve a two-year term through Jan. 31, 2019.