During your commute, you may have noticed the construction of sound walls on Mopac.

Central Texas Regional Mobility Authority officials said about 9 to 10 walls are being replaced or reinforced because of cracking.

The problem was discovered in spring of this year by inspectors, and all construction of sound walls halted for the year until last week as a cause was investigated.

New panels are going to be installed or a cap will be added to the foundation the panels sit on.

The cause of the cracking?

"Essentially, there was too much pressure on the bottom panels,” said Steve Pustelnyk, director of community relations with the Central Texas Regional Mobility Authority. “That was putting some stress cracking into those panels.”

The mobility authority said their contractor – CH2M – is paying out of pocket for these repairs and replacement costs.

"The walls have to be built to the specification that was provided,” said Pustelnyk. “So at this point any cost to rework the walls is at the contractor's bottom line and is not an expense public of taxpayer will be subject to."

CTRMA said most of the existing walls do not have cracks – but they are being reinforced as a precaution.

"If they haven't cracked already, then they're going to be retrofitted to make sure they don't crack in the future,” said Pustelnyk.

As crews fix sound walls, they'll also install new ones from Anderson Lane to Lady Bird Lake.

It is estimated it will be finished by next summer.