It's not a warning board. It's a crash beam to protect the bridge, because the consequences of damaging the rail bridge are much worse than those of canopening

It's not a warning board. It's a crash beam to protect the bridge, because the consequences of damaging the rail bridge are much worse than those of canopening a truck that ignored numerous obvious warnings, including a flashing one triggered by a vehicle height sensor. The bridge itself has already been raised by 8 inches (though it's still unusually low), which would have also cost a fair bit. They haven't just gone and put an unnecessary "warning board" under it. There are many more incidents, BTW. Scroll down for more videos.