Why Does Tacoma’s Hylebos Bridge Keep Closing?

If it feels like Tacoma keeps announcing that the Hylebos Bridge is closed — and then announcing that it's open again — you're not imagining things.

The City announced Tuesday that maintenance on the bridge was complete and both roadway and waterway traffic had reopened, one day after closing the bridge so crews could inspect its centerlock. The work had originally been expected to potentially last through Aug. 27, so Tuesday's reopening came earlier than anticipated.

But this week's closure is just the latest in a string of interruptions involving the bridge this year. And the reasons help explain why keeping the Hylebos operating is more complicated than maintaining an ordinary overpass.

The Hylebos is a movable bridge built in 1939 and rehabilitated in 2012. It carries roadway traffic across the Hylebos Waterway but also has to open for ships. In fact, federal law generally requires movable bridges over navigable waterways to open for marine traffic, and the Hylebos operates on request 24 hours a day.

That means there are considerably more moving parts than on a conventional bridge.

One of those caused trouble in April. During routine testing on April 20, the bridge failed to open properly. The City later determined that corrosive marine air had caused electrical shorts within the bridge's operating system. It reopened two days later.

Then came the centerlock. On June 11, Tacoma closed the bridge for five hours specifically to replace it. The centerlock is a critical safety component that locks the two spans together when the bridge is down, keeping the roadway stable for vehicles and preventing the spans from lifting while traffic crosses.

That same component was the focus of this week's maintenance. The City closed the bridge Monday while crews inspected the centerlock and reopened it Tuesday after completing the work. The City's announcement does not say that the June replacement itself “failed,” so it would be premature to characterize this week's inspection that way.

There was another closure July 27, with the bridge reopening the following day. The City's brief announcements don't provide enough information to establish that the July closure was caused by the same centerlock issue, so the recent closures shouldn't all be lumped together as one recurring mechanical failure.

The bridge has faced problems from the water, too. In October 2023, a tugboat struck the protective fender system surrounding the bridge. The NTSB later found that the fender system was already deteriorated, which contributed to the severity of the damage. The bridge itself wasn't damaged in that collision, but its protective fender system had to be replaced. Tacoma's emergency repair of that system later won a state public-works award.

So why does the Hylebos seem particularly troublesome? Part of the answer is simply what it is: an 87-year-old movable bridge operating around the clock in a marine industrial environment. It has electrical and mechanical systems that an ordinary fixed bridge doesn't have, sits amid corrosive salt air, and must accommodate both road vehicles and commercial marine traffic. That's a demanding job for any piece of infrastructure.

That doesn't necessarily mean the bridge is unsafe. Tacoma Public Works inspects and maintains the City's bridges under state and federal requirements, and closures like Monday's allow crews to inspect or repair components rather than continue operating when there's a concern.

What should drivers expect? For now, the bridge is open and the City hasn't announced another closure. But given the bridge's age, movable machinery and recent maintenance history, occasional inspections and closures aren't surprising. For people who regularly travel through the Tideflats, City closure alerts remain worth watching.

The good news this week is simple: the Hylebos is open again. The bigger story is that keeping an 87-year-old movable bridge functioning in Tacoma's working waterfront requires considerably more attention than most drivers probably realize.

👉 If you’re interested in reading a great article on the history of the Hylebos, you can find it here.