The Texas Transportation Commission said it authorized the state Department of Transportation to advance a $500 million set of projects to add both toll and non-toll capacity along 9 miles of US 183 in north Austin.

“This expansion is going to address congestion and improve mobility and safety for drivers,” said Terry McCoy, TxDOT’s Austin district engineer. “As traffic in north Austin increases, this multilane expansion will offer options for commuters.”

It will proceed as two projects, the announcement said, with TxDOT managing a design-build contract for a $120 million investment to build a new general-purpose highway lane plus shared bike and pedestrian paths, new sidewalks and cross-overs for bicycles and pedestrians.

The Austin American-Statesman newspaper noted that the road now narrows in several points to three lanes per side from four, and that the planned project will add the fourth lane to either the northbound or southbound side at various places.

And through a partnership with TxDOT, the Central Texas Regional Mobility Authority will spend $380 million to add two toll or “managed lanes” in each direction and flyover bridges connecting them to new managed lanes on the Loop 1 freeway, formally the Mopac Expressway.

The newspaper said the US 183 toll lanes “would be in the highway’s broad center median, currently walled off by concrete barriers from the existing lanes.”