Dear Editor ,
I would like to ask our engineers a very simple question to do with the ramp that is stationary and permanently anchored, while at some point attached to it by hinges is a drawbridge – anchored to a pontoon.
The pontoon obviously is to allow the ramp to move up or down in tandem with the tide, since the pontoon is sitting in the water and the ramp is permanently held to the pontoon. The ramp is expected to move up or down since it is attached to the pontoon, but this would only be possible if the approaching end of the pontoon is hinged to the drawbridge, and not permanently anchored as it would appear to be at the moment on the Supenaam stelling.
The concrete curb that came apart was either from when the tide ebbed or from the weight of whatever caused the ‘I’ beam to buckle.
The gantry that I know about at NA’s stelling and at Rosignol is operated with the same concept; instead of a pontoon the gantry at the water’s edge lifts the ramp in relation to the tide, while the approaching end of the ramp that facilitates traffic to the ferry is hinged.
Yours faithfully,
Michael Tannassee
