Can you provide any historical info on the bridge?
The weight limit is 15 tons for a vehicle with axles less than 25 feet apart and is 27 tons for vehicles larger than that. Also if your wheels are eight feet apart, you can use the supports allowing you to drive up to 21 tons of vehicle across the bridge. Assuming you can get past the lock. I have a key if anyone wants to get onto the island. Just email me and ill come by and unlock it for you.
You can see a different, shorter pier adjacent to the piers for the Bailey truss in the streetview.
Perhaps those were for the bridge the archaeologist crossed?
the archeologist crossed "a" bridge to this island in 1938 but I might have assumed incorrectly assumed that it was the same bridge. It probably replaced that bridge but I wish I knew when. I saw the patent date of the design after I had already submitted the entry.
I doubt this was around in 1938, as the Bailey truss was in development in the UK at the time.
My husband, Kevin Collins, grew up in Potomac Farms in the 1960's. His family even had a garden on the island for many years. I remember him saying that it was a sod farm for quite some time, and I believe it was owned by a Bill Brockett.
The original piers were from a bridge that was in existence in the early 1960's. He remembered that a truck, possibly overloaded and driving too quickly, attempted to cross the bridge, got too close on one side and caused the pier and bridge to topple. His memories were that a crane was necessary to get the truck out of the river.
Hope this answers some questions.