Town-bound drivers who use the Wilson Tunnel will be able to use only one lane for at least the next several weeks, after state transportation officials found structural damage to the tunnel ceiling.

Crews closed the tunnel in the town-bound direction over the weekend and installed wooden support beams from the floor to the ceiling after inspectors Friday discovered that eight steel rods that help the support the ceiling are deteriorated, according to state Department of Transportation spokesman Tim Sakahara.

Inspectors also found cracks in the concrete near vents in the tunnel, which, like the steel rods, will need to be repaired, Sakahara said in a statement.

Nonetheless, he added, the tunnel is safe. It’s not clear yet what caused the deterioration, and workers found the damage during a routine inspection, Sakahara said.

The state DOT will keep the left town-bound lane closed for several weeks while crews handle repairs and inspect the rest of the Likelike Highway tunnel. It’s not yet clear whether the right lane will have to be closed at any point during the work. If it is, Sakahara said, the DOT will try to schedule that full town-bound closure outside of rush hour.

The DOT has reduced the tunnel’s speed limit to 25 mph from 35 mph during the work, according to Sakahara’s statement.

In the meantime, drivers should consider using Pali Highway and H-3 freeway to avoid all the work, he said. There’s no set date on when the damage might be fixed.

Crews do what Sakahara described as a “full” inspection of the 55-year-old Wilson Tunnel every two years, and periodic visual inspections more often. A visual inspection caught the tunnel damage. The H-3’s Tetsuo Harano tunnels, the Pali Highway tunnels and all other tunnels under state jurisdiction get inspected regularly under the same plan, Sakahara said.