Repairs on two Oahu bridges will begin Monday, the City and County of Hono­lulu announced this week.

Construction on Rainbow Bridge over Anahulu Stream in Haleiwa will last for approximately one year, and work on the Dillingham Boulevard Bridge over Kapalama Canal in Iwilei will last for around four months.

Both bridges are being repaired because of “advanced deterioration” caused by chipped concrete and cracks on elements of the bridges, which is affecting their load-carrying capacity, the city Department of Design and Construction said.

The work on Rainbow Bridge, also known as the Kamehameha Highway Bridge No. 603, will include repairs to concrete delamination and cracks, installation of corrosion control technology and painting, and is intended to “protect the bridge from corrosion and improve its structural integrity, thereby enhancing the longevity of the bridge and public safety,” a news release said. Kaikor Construction Group is the contractor for the project.

Originally built in 1921, Rainbow Bridge had emergency repair work done in early 2022, consisting of the installation of a silt curtain and grout bags.

Work will take place from 8:30 a.m. to 3:30 p.m. Monday through Friday, except on holidays. The bridge will remain open to vehicles during construction, and a temporary lane closure might be implemented if necessary. One sidewalk will remain open to pedestrians at a time during construction. Drivers and pedestrians should account for additional time when going through this area, and observe all signs, traffic controls and Special Duty Officers.

Recreational use of the waterway will continue throughout the construction period along about half of the bridge between either the Kahuku abutment and center pier or the Waialua abutment and center pier.

The work on the Dillingham bridge between Kohou and Kokea streets will repair spalled concrete on the substructure to “enhance the lifespan and structural integrity of the bridge,” the news release said.

Dillingham Boulevard Bridge was originally built in 1930, and hasn’t been repaired since 2004, when it got a seismic retrofit to make it more resistant to events such as earthquakes.

Work will take place between 7 a.m. and 3:30 p.m. Monday through Friday. Workers will close one sidewalk across the bridge at a time during construction. Vehicles will still be able to cross the bridge throughout construction, with traffic coordinators under contractor Sea Engineering present during daytime work. “No parking” signs have been posted along portions of Kokea Street on both sides of Dillingham Boulevard.

Repairs for both bridges are being funded solely by the city and county.

“Every effort will be made to complete this essential work as quickly and with as little inconvenience to the community as possible,” the release said. “We appreciate the public’s cooperation during this project and thank them for their patience and support while the City works to improve our local infrastructure.”

Questions, comments and concerns can be submitted to the Department of Design and Construction by calling 808-768-8400.