David Armbrust, a Central Texas Regional Mobility Authority board member, had a hypothetical question regarding community engagement Wednesday: If he, as a citizen, called and asked when MoPac construction will be completed, what would the answer be?

The board burst into chuckles.

There’s still not a hard end date for the $200 million project to add a tolled express lane on the north stretch of MoPac Boulevard (Loop 1), but contractors estimate more sections should be open by the end of summer, mobility authority spokesman Steve Pustelnyk told Armbrust this week.

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The project includes a toll lane from West Cesar Chavez Street to Parmer Lane, along with sound barrier walls and pedestrian improvements. It was originally slated to be completed in September 2015. Last October, the northern half of the northbound toll lane opened from Far West Boulevard to Parmer Lane.

Board members on Wednesday approved extending the engineering contract and work authorization on the project until Dec. 31, which Director of Engineering Justin Word called "reasonable based on where we sit on available funding and overall anticipated schedule for the project." The extension doesn’t increase the cost of the work.

Most of the work will be done this summer, Word said.

Mobility authority staff members emphasized progress made on the work and the performance of the operating section of the express lane. The lane logged 20,020 transactions the week of March 27, the most since it opened in October.

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Underpasses between Lake Austin Boulevard and Enfield Road are "close to looking very much done," with the addition of large concrete panels, Pustelnyk said. Paving is imminent, he said.

A northbound exit ramp to RM 2222 is expected to be reopened to traffic in the next week or so. A northbound auxiliary lane from 35th Street to 45th Street will likely reopen by the end of next month. A segmented barrier on that side of the road will also be removed, bringing the road to its full width.

"A lot of things are going to change in the next month," Pustelnyk said.