ME - Platform bridge to lighthouse collapses, 11 injured - Arrowsic, 9 Sept 2023

[ifindedout]

Nearly a dozen injured after platform to lighthouse collapses in Arrowsic

According to officials, 11 people were on the platform when it collapsed, causing them to fall onto the rocks and mud below.

www.newscentermaine.com

ARROWSIC, Maine — Nearly a dozen people were injured Saturday when a platform bridge to the Doubling Point Lighthouse collapsed.

Emergency officials were dispatched to the historic coastal Arrowsic destination shortly before 1 p.m. Five people were brought to a nearby hospital, and six people were treated at the scene, Bath Deputy Fire Chief Chris Cummings told NEWS CENTER Maine.

[...]

The light tower, accessible by land, was open to visitors Saturday as part of the annual Maine Open Lighthouse Day. However, according to its website, visitors are welcome year-round between 9 a.m. to 5 p.m.

"The lighthouse is an active Coast Guard aid to navigation. The lighthouse is owned and managed by the Friends of Doubling Point Lighthouse," the listing on the events page states.


Doubling Point Light and the nearby Doubling Point Range Lights guide ships through the channel of the Kennebec River which provides access to naval shipbuilders Bath Iron Works. Wikipedia's entry has a good head-on view of the bridge involved, along with the light's basic history.

Doubling Point Light - Wikipedia

en.wikipedia.org

This incident will probably be due to one, some, or all of the following:

• deterioration of the wooden bridge;
• load limit of the bridge being exceeded;
• resonance on the bridge created by people stepping abnormally, running, or jumping up and down.

MOO

ETA: image of collapsed bridge

 

[Warwick1991]

One of the photos in the Wikipedia article on the lighthouse linked above shows the bottom chord (beam) of the trussed supports sagging, meaning they are probably undersized. The most questionable structural connection is where the trussed supports connect to a wood walkway around the tower.

If 11 people were on the footbridge, that shouldn’t really be an overload, depending on where they were.

Since this lighthouse has been managed by a nonprofit group, I have to wonder whether a professional engineer has been involved in the maintenance of the footbridge. The link above to the Friends of Doubling Point group leads to a page indicating that the footbridge was rebuilt to an earlier 1885 configuration in 2000. Perhaps returning to an earlier configuration led to a redesign that was not sturdy - perhaps replaced at a later date due to deficiencies. Just speculation at this point…..

 

[LadyL]

One of my 'irrational' fears.

 

[Warwick1991]

On the Friends of Doubling Point website, I see that the footbridge was rebuilt to a version before 1985, not to an 1885 version. I shouldn’t post when I’m half asleep…. The website notes that the US Coast Guard rebuilt the footbridge in 1985 using pressure treated lumber, and that the Friends rebuilt the footbridge to look like its predecessor. Based on its pre-collapse appearance, I have my doubts as to whether an engineer was involved.

I am sure that the USCG would have had an engineer involved in the 1985 work. Until recently, Maine had no building code, and it is possible that the footbridge reconstruction was not built or inspected to any standards. The Friends might have found old drawings or photos of the footbridge, and rebuilt the footbridge bridge without checking structural capacity.

I am speculating at this point. I’m sure more information will be published. I hope those hospitalized recover soon.