1:13 AM: If you have to cross the Duwamish soon, don’t head for the low bridge. It’s been closed to surface traffic for more than an hour; SDOT says via Twitter that it’s “mechanical trouble.”
1:30 AM: The bridge had trouble Tuesday afternoon, too.
2:09 AM: Still not open.
4:58 AM: Metro is rerouting buses over the 1st Avenue South Bridge.
5:59 AM: The low bridge is still out of service and SDOT has finally confirmed that means ALL modes – closed to bicyclists and pedestrians as well as motor-vehicle drivers. No word yet on how much longer this is expected to last.
6:51 AM: The low bridge has just reopened.
10:40 AM: Here’s how SDOT spokesperson Ethan Bergerson answered our question about what went wrong:
The Spokane St bridge was closed last night from approximately 11:30 p.m. to 6:45 a.m. due to an intermittent mechanical issue which triggered a safeguard preventing the bridge gates from being opened. This is an intentional safety measure which ensures that people cannot travel over the bridge until the underlying mechanical issue is resolved. Our engineers and maintenance staff worked through the night to complete the immediate work to address the problem and verify that it was safe to reopen the bridge. We are still working to understand the underlying root cause, and determine next steps to ensure that this does not happen again.
4:05 PM: An update from SDOT:
There were two separate mechanical issues which occurred on the Spokane St bridge, both of which triggered the safeguard of closing the bridge gates to the public.
On May 11 at roughly 4:10 pm, the tail lock on the east side of the bridge triggered an alarm, which is related to a known issue with the hydraulic arm that extends/ retracts the locking pin. Engineers and maintenance staff were able to address this issue and reopen the bridge at about 7:00pm. We are planning to address this issue by building a new hydraulic arm, and will also refurbish the existing arm as a backup for future use.
On May 11 at 11:05 pm, a small component within the traffic barrier turning mechanism got stuck preventing the gate from opening. As a safeguard, the gate is programmed to shut down if something is interfering with its normal operations in order to prevent further damage. When the gate shut down, it triggered other control system alarms and safeguards, resulting in all gates from closing. Our engineers and maintenance staff worked through the night to complete the immediate work to address the problem and verify that it was safe to reopen the bridge at about 6:15 a.m.