Overnight drilling comes to Ketchikan's aging viaducts, part of a plan to repair them now and replace them later

Drilling crews will work overnight in Ketchikan in late August, boring into Tongass Avenue and Water Street to gather ground data for two 1950s viaducts that together carry more than 14,000 vehicles a day. The work supports a state plan to repair the aging structures in the near term and replace them further out.

The two viaducts date to 1955 and 1956, and age is showing. The most recent national bridge inventory rates the Water Street viaduct in poor condition and the Tongass Avenue viaduct in fair condition, ratings drawn from a 2023 inspection — before an emergency repair one of them received around 2024. Both carry heavy daily traffic through the heart of Ketchikan.

The drilling is the groundwork for the near-term fixes. A contractor will bore 13 holes over about four to five days, checking pavement thickness and probing for voids beneath the roadway, and taking samples where an abandoned bridge near the Jim Creek culvert is set to be removed. Because Tongass Avenue and Water Street are so busy, the work will run overnight — roughly 10 p.m. to 6 a.m. under a noise permit from the city — with all lanes and sidewalks staying open during the day.

The state's plan for the corridor runs 15 years across five projects. Three are funded and could begin as early as 2027: spot pavement repairs, spot repairs to the bridges themselves, and replacing the Jim Creek culvert. The department describes the bridge repairs as measures to prevent unexpected closures and keep the structures safe until they can be replaced.

Replacing the two viaducts outright is the larger, longer-term piece, and it does not yet have funding attached; new construction is placed at 2030 or later. According to a borough manager's report late last year, the state considers those replacements the region's top priority for incoming funding — with a shorter, roughly 10-year timeline coming into play only if load restrictions or closures hit the bridges first.