Koko Crater summit and the railroad tracks that hikers climb to reach it will be closed from June 15 until the end of July, the Honolulu Department of Parks and Recreation announced in a statement today.

The closure will be done to alleviate safety concerns about crumbling World War II-era structures at the summit of Kohelepelepe. The moribund structures were constructed atop Koko Crater in 1942 by the U.S. military and served as a radar station, which was returned to the City and County of Honolulu when it was deactivated in 1966.

Since then, the installation has “degraded severely,” the statement said, and to address this the project intends to: remove debris from tunnels and shafts; seal the shafts, vents, and tunnels; and remove deteriorated steel decking and framing.

Signs will be installed at the summit and tramway trestle to warn visitors of hazards.

This project, to be performed by Kaikor Construction Company, Inc. at a cost of just over $439,000, does not include work on the tramway track, but “the city is in the early planning stages of exploring options for tramway improvements,” the statement said.

Nearby residents and district park users should expect increased air traffic in the area between 7 a.m. to 3:30 p.m., when a helicopter will be carrying materials and equipment to the summit. Operating hours at the Koko Head Shooting Complex may also be affected, and the playing fields at Koko Head District Park may see intermittent closures, DPR said.