Adding two toll lanes in both directions on US 183 between RM 620 and MoPac is likely to cost between $500 million and $600 million.

This figure is from preliminary engineering and design estimates. Schematics showing the location of toll lanes and access points were presented at a March 10 open house event at Westwood High School for the 183 North Mobility Project.

Behind the project is the Central Texas Regional Mobility Authority, which is overseeing the MoPac express lane project, and the Texas Department of Transportation. The proposed project on US 183 launched in August 2013.

Drivers would be able to enter or exit toll lanes on the north end of the project at RM 620 or continue on Toll 183A to Cedar Park. The mid-point access is near Duval Road, and the southern terminus is at MoPac, where drivers would have direct access to the MoPac express lanes under construction. Drivers could also exit or enter the US 183 toll lanes at Burnet Road.

The project also includes safety improvements, such as adding auxiliary lanes, which provide drivers with room to merge to or from main lanes and the frontage road.

Since the previous open house event in summer 2014 the Mobility Authority sifted through public feedback and incorporated several suggestions from the community, such as adding $5 million to fill in about 4 miles of gaps in sidewalks along the frontage roads and adding a shared-use path, said Rick L'Amie, director of communications for the Mobility Authority.

"There are just a lot of incomplete sidewalks," L'Amie said. "People are just walking in the grass."

Public input also led the Mobility Authority to propose extending a fourth general-purpose lane throughout the entire corridor to eliminate traffic having to merge into three lanes in part of the corridor.

Staff members studied the possibility of connecting the US 183 express lanes directly to the MoPac express lanes, L'Amie said. This will also make it feasible for Capital Metro to use the toll lanes on both US 183 and MoPac to connect Northwest Austin with downtown.

"We spaced the entrances and exits farther apart to make that work," he said.

Cedar Park resident William Davis said he likely will not use the toll lanes on US 183 or MoPac but understands the importance of having the option to connect to both.

"I think that's great. If you didn't have that, the project is worthless," he said. "I can see the need for [the direct connect]."

The Mobility Authority anticipates receiving environmental clearance in early 2016 and will host another open house in the fall.

For more information about the 183 North Mobility Project, call 512-996-9778 or visit www.183north.com.