In about three months drivers could see the north and southbound Mopac toll lane open up. The MoPac Improvement Project puts a variable toll lane in each direction from Parmer Lane to Cesar Chavez. It's been a long time in the making with at least a year of delays.

The contractors have faced several problems along the way like unexpected utility lines along the route and harder than expected rock when digging underpasses. Those underpasses are nearly complete.

"We waited for this particular aspect a year or longer than we thought," said Central Texas Regional Mobility Authority Executive Director Mike Heiligenstein.

The irony? The original plan was to build overpasses.

Once open, the MoPac underpasses will connect Loop 1 with downtown north and southbound.

"This is essentially the last improvement that you're going to be able to make on MoPac, unless for some reason the Union Pacific decides to reroute their trains," Heiligenstein said.

Now that the project is closer to completion, a lot of the work happens at night. It keeps MoPac traffic clearer and the contractor cooler.

"We expect the contractor to be able to deliver the entire project for opening by mid-September,' Heiligenstein said of contractor CH2M Hill.

After that September opening, the contractor will still need to complete some painting, bridgework and sidewalks.