ION - Waterloo Region's Light Rail Transit

[JoeKW]

You say that, but it could happen!  And so, it must be accounted for.  An overheight load would destroy the OCS, as well as pose a huge safety concern.

I think it is far more likely that an oversize road-based load will take out some OCS than that a train from the north will do so. Actually I think an oversize road-based load is more likely than a train from the south, but even more so than a train from the north.

I too am curious what the sensing technology is.  Hanging horizontal bar with a limit switch?  Through-beam photo sensor?  It has to be robust and able to handle the weather.

Exactly the same horizontal bar that goes on some parking garage entrances, hooked up to some sort of motion sensor to detect the horizontal bar being hit by the load. I just like the idea of the same black-and-yellow striped bar getting shoved by the train.

Or build an enormously strong concrete arch exactly the size of the loading gauge. Any train can pass, but any part that doesn’t fit gets broken off or bent to fit the envelope.  

That reminds me of the guards in front of the Victoria Bridge in Montreal (although not concrete):
https://goo.gl/maps/FvBvQQ7Z83w