Three well-traveled bridges built more than 50 years ago over the man-made waterways of Hawaii Kai will undergo a $1.6 million rehabilitation, city officials say.

Work began Monday on Hawaii Kai Drive Bridge, the Keahole Street Bridge over Kuapa Pond crossing the Hawaii Kai Marina, and the Wailua Street Bridge, also over Kuapa Pond, the city said.

All three spans were built around 1970, and all suffer the effects of time and the elements, according to Cindy Cromwell, city Department of Design and Construction spokesperson.

“The scope of this project is to repair the heavily deteriorated concrete columns,” Cromwell told the Honolulu Star-Advertiser.

Although portions of the bridges are in need of repairs, she stressed they are all still safe. “There is no immediate danger to the public,” she said.

Honolulu-based Sea Engineering Inc. was hired for the project’s design and construction. The firm will demolish and restore spalled concrete in the bridges’ substructures. The work is meant to extend the life span of the bridges, address potential hazards and ensure the bridges remain safe for the public, the city said.

The project is expected to take about six months to complete, barring unforeseen conditions and weather events.

Work hours will be 7 a.m. to 3:30 p.m. Monday through Friday, excluding holidays. Construction will be performed in phases to minimize inconvenience to the public. The bridges will remain open to vehicular and pedestrian traffic.

However, temporary lane closures may be implemented if necessary.

“Traffic impacts on the roadway will be limited to single lane closures only on days when concrete will be poured,” Cromwell said. “The lane closure hours will be scheduled between the hours of 8:30 a.m. to 3 p.m. to avoid high traffic volume times.”

Access through the Hawaii Kai Marina waterway will also be affected by construction equipment, but all bridge locations will remain navigable, the city said.

“For bridges with multiple navigable spans, only one span will be partially blocked if necessary,” Cromwell said. “For those with a single navigable span, the contractor will stage equipment to allow vessel access at all times.”

She added that “bridge piers will be repaired one at a time, with construction equipment staged immediately adjacent to the pier under repair.”

Motorists, vessel operators and pedestrians should allow extra time while traveling through the area.

Drivers should observe all posted signs, traffic controls and special-duty officers. The contractor will also place “No parking” signs along affected areas near each bridge site one week in advance. Drivers are also asked to observe the dates and times of these notices.

Vehicles parked on posted streets will be towed at the owner’s expense.

Greg Knudsen, a Hawaii Kai Neighborhood Board member, said it was too early to say how the city’s bridgework project might affect the community, particularly vehicle traffic near Hawaii Kai Towne Center on the 300 block of Keahole Street, which features an often busy, crowded Costco Wholesale store, among other businesses.

“Maybe during certain rush hours it won’t be as easy,” he told the Star-­Advertiser, “but we deal with backups along Kalanianaole (Highway) all of the time.”

Still, Knudsen said the bridgework was “obviously necessary.”

“It’s good that they’re working on it instead of waiting for it to be totally shut down,” he added. “So that part, of course, is good.”

BRIDGING THE GAP

A $1.6 million renovation project began Monday on bridges over Keahole and Wailua streets and Hawaii Kai Drive. The project is expected to take about six months to complete.