Lawrence city commissioners on Tuesday agreed to a plan that will close 15th Street near Kansas University during the summer of 2013.

The closure will be part of a $6 million project to rebuild Iowa Street from Yale Road to the Irving Hill Overpass. Cross-traffic on 15th Street, which is known as Bob Billings Parkway west of Iowa, will complicate the project. City commissioners at their weekly meeting agreed with engineers to close 15th Street from just after KU’s graduation and until July 31 when students begin to move back into the city.

Commissioners unanimously agreed to offer a $5,000-per-day incentive — up to $50,000 — if the contractor completes the job early. Commissioners also approved a $5,000-per-day fee that will be charged to the contractor if the project is completed late.

The city and the state are expected to take bids on the project by the end of 2012.