Let’s consider a design problem. You have an earthen fort that is part of a defensive line that goes back to the 17th century. It has fallen into ruins over the years, but it’s historically significant and is in the process of being restored. The owners want to be able to access it from the front so they can incorporate it into their system of parks and greenways, but there’s no way over the moat. The obvious solution is to build a bridge, but it’s going to spoil the history of the site. What do you do?
The site is Fort de Roovere in the Netherlands. When the question was posed to RO&AD Architects, they came up with a solution that impressed the hell out of me, the jaded bridge engineer. It’s been called a ‘trench bridge’ and a lot of sites on the internet have taken to referring to it as the ‘Moses Bridge’. I have to say, this is some impressive outside the box thinking.
The bridge is built out of wood, and waterproofed with foil. A stair case was cut into either side of the moat and a bridge was built below water level. The bridge has railings on either side that keep it, and any pedestrians, dry. The top of the railing is at water level so it isn’t visible. From any significant distance only the heads and upper bodies of pedestrians using the bridge are visible. The foil is meant to waterproof the bridge, and the wood used is specially treated to keep out fungal decay.
I would love to see the design plans for this thing. The wood of the railings would have to be pretty impressive on order to hold back all that hydrostatic pressure, and there’s no visible cross-bracing so each side stands alone. I also have to assume they have some way of controlling the water level. In the pictures there is very little distance between the water level and the top of the bridge rails so it seems like any decent rain could raise the water level enough for it to pour over the top and flood the bridge. I assume the moat has some way of controlling the water level to keep that from happening. Let’s just hope it’s not stagnant enough to develop a hungry population of mosquitoes.
Apparently the design was inspired by a respect for the original builders of the fort. The design team felt it would be disrespectful to put in a high level bridge that would blatantly violate the original intent of the fort. I think they did a great job conceptually, but the attempt to respect the original fort backfired. The innovative nature of the bridge steals all the attention away from the fort itself. If you do an internet search for Fort de Roovere 95% of all the hits you get are about the bridge.
The pictures below are all copyright RO&AD Architects, and I got them from the Daily Mail.