School’s out. Road construction is in.

The day after Kansas University’s commencement ceremonies has been the traditional start of the road construction season in Lawrence, and on Monday motorists won’t be able to miss it.

Crews will close to all traffic Bob Billings Parkway/15th Street at Iowa Street, a closure that is expected to last into August. Construction work also will affect traffic on a separate portion of Bob Billings Parkway and on Wakarusa Drive.

“May 20 has been the day embedded in my mind for the last year,” City Engineer David Cronin said. “We’re going to have a lot going on.”

City officials try to cram as much roadwork as possible into the summer season to take advantage of the time period when many Kansas University students have left the community. Contractors are pressured to get work done before mid-August, when KU classes resume.

“It is stressful for us in a way, but our contractors know our expectations and know these dates are important to us,” Cronin said. “We expect to hit our completion dates with good weather.”

Here’s a look at the projects that begin on Monday:

• Phase II of the Iowa Street reconstruction project will involve prohibiting any traffic from Iowa Street from turning onto Bob Billings Parkway to the west or onto 15th Street to the east. Traffic on Iowa Street will continue to be one lane in each direction. The intersection work is expected to last until Aug. 16.

Motorists wanting to go west on Bob Billings Parkway can snake their way through West Campus, via Constant Avenue and Irving Hill Road, which will allow motorists to emerge onto Bob Billings Parkway via Crestline Drive.

Motorists wanting to go east on 15th Street — onto KU’s main campus — don’t have such an easy detour. The city is recommending motorists access campus either by using Ninth Street and entering through the Mississippi Street gateway or using 19th or 23rd streets to access campus through the Naismith Drive gateway.

The closure of Bob Billings/15th Street is needed to make dramatic changes to the intersection, Cronin said. When it is reopened in August, the intersection no longer will look like it is built on the side of a hill. Crews will raise the western leg of the intersection (Bob Billings) so that it will be on the same grade as the eastern leg of the intersection (15th Street).

The project also will include adding dual left-turn lanes on Iowa Street for both north and southbound motorists. Dedicated right-turn lanes will be added at all approaches of the intersection.

“It is going to improve the capacity of the intersection by quite a bit,” Cronin said. “On game days, when people are trying to get in and out of the university, it will be better.”

The intersection work is just one phase of a larger project to rebuild Iowa Street from the Irving Hill Road overpass to Harvard Road. The project involves adding a center turn lane to much of Iowa Street, along with a new road bed and pavement.

The entire project is scheduled to be completed in November. Despite the rain and snow, the project is on schedule, Cronin said.

“There were a couple of breaks in the weather where we were lucky to be able to get some pavement in,” Cronin said. “And the contractor has been doing what work he can in the rain.”

• Crews will be rebuilding a portion of Bob Billings Parkway from Iowa Street to Kasold Drive. That project also is expected to last until Aug. 16.

The project will remove all traffic off of the two eastbound lanes of Bob Billings Parkway and shift it onto the westbound lanes of Bob Billings. That means traffic on that portion of Bob Billings will be one lane in each direction.

• Construction work will affect traffic on Wakarusa Drive, immediately north and south of Bob Billings Parkway.

Phase I of the project will close the portion of Wakarusa immediately south of the Bob Billings intersection. Motorists will need to use a combination of Research Parkway, Research Park Drive and Bob Billings to get through the construction zone. Work on phase I of the project is expected to last until mid-July.

Crews then will close the section of Wakarusa Drive just north of Bob Billings. Motorists will need to use a combination of Legends Drive, Research Park Drive and Bob Billings to get through the construction zone. Phase II is expected to last until mid-August.

Bob Billings will remain open to east/west traffic throughout the project, but turning movements off of Wakarusa onto Bob Billings, and vice versa, will be limited.