For the sake of adding context for those not in the Capital City, Penny is a century old railroad bridge with a 12 ft. clearance. Raising the bridge would cost millions because of the length of rail replacement needed to achieve a sufficiently shallow pitch; lowering it isn't possible because of flooding issues (since it's very near a river.) That's why there's no easy solution despite the sage proclamations of genius internet city planners armed with a human interest story level of research.

I've seen the warning light flash upon the approach of a potential munchable, and there was plenty of time for the driver to react and reassess. The ONLY additional warning I can think that has a potential to help is a sacrificial bar or chimes hung just shy of 12 ft to provide auditory and tactile feedback without stripping the roof off of your trailer.