Age appears to have caught up suddenly with the 55-year-old Wilson Tunnel — and that means the thousands of commuters who drive Likelike Highway into town each day will have to endure about two months of repairs and lane closures.

State transportation officials said Friday it could take as long as eight weeks to fix the tunnel’s town-bound wing and that drivers would likely face full closures in that direction from 9 p.m. to 4 a.m. starting in several weeks, once all the necessary parts and materials arrive on the island.

The Wilson town-bound has already been trimmed to one lane since Sept. 25, when, according to state officials, inspectors first discovered eight broken stainless-steel rods that are supposed to help hold up the tunnel’s ceiling at the center. Since then subsequent inspections of the 750 or so rods that help support the ceiling in both directions revealed 22 additional broken ones — all in the town-bound direction, according to state Department of Transportation officials.

Inspectors also found cracks in the concrete near vents in the tunnel, DOT officials said.

Ed Sniffen, the DOT’s deputy director for highways, said Friday that the Wilson Tunnel remains safe for commuters despite the damage they’ve found. Some 9,500 commuters use the passage to cross the Koolau Mountains during the morning rush hour, he said.

Nonetheless, the rods are “definitely important” to help hold up the ceiling even if they don’t support the entire tunnel structure, which continues above the ceiling, Sniffen said. In one stretch of tunnel, workers found six steel rods in a row snapped, and “that was an area of absolute concern,” he said.

“We wanted to make sure that we found the broken rods and we fix those broken rods right now,” Sniffen said during a media briefing Friday. “We wanted to make sure that none of the portions of the ceiling fell on any of the motoring public. That’s why we shut everything down, so that we could assess that.”

Workers installed wooden support beams from the floor to ceiling and lane barriers last weekend. While the work continues, the speed limit through the town-bound lanes is 25 mph.

The DOT is still trying to determine what caused the rods to break — they were found to be undamaged during the tunnel’s last full, biennial inspection in 2013, Sniffen said. However, officials believe that strong vibrations from the air that moves through a shaft above the tunnel ceiling might have stressed the rods. “Once one of them failed, it put stress on the next and the next,” Sniffen said. DOT officials still haven’t determined why the rods broke only town-bound and remained intact in the Kaneohe-bound direction.

The report for the 2013 inspection, released Friday along with several others, does recommend that the state “seal cracks in air shaft deck.” It’s not clear whether that sealing occurred or whether it directly applies to the problems that have prompted the latest repairs.

Sniffen said Friday that DOT will now start inspecting the Wilson Tunnel every year instead of every other year. The broken rods are all originals from when the tunnel first opened in 1960, according to DOT.

DOT doesn’t expect to find the same problems right now at the other two tunnels that cut through the Koolaus, at Pali Highway or H-3’s Tetsuo Harano Tunnel, because they’re designed differently and the Harano Tunnel is younger, Sniffen said.

At the Pali there’s no air shaft above the ceiling, so “we can see exactly what’s happening in that tunnel because there’s nothing blocking it,” Sniffen said. Inspectors will continue to examine those tunnels every other year, he added.

Meanwhile, at the Wilson Tunnel, DOT is considering contra-flowing lanes to allow more town-bound commuters to travel through the tunnel during the morning rush, but it hasn’t made a final decision, according to department officials.

The work in the coming months will be an emergency repair, and once it’s done DOT will start another project to refurbish the supports for the tunnel, Sniffen said. He said he didn’t want to give an estimated cost for the emergency work since the price is still being negotiated with contractors.