Bridge height apps

Yeah, ditto about LowClearances.com, I went to check and found them gone too. Their data base works pretty well though. It has alerted me in the past when I've gone near a low bridge that wasn't on my direct route. So it does work, but it didn't list every low bridge/underpass.

Not a direct answer to your question.

Garmin includes clearances into its North American maps. You put the dimensions of your rig into the device as well as the route planner and it routes you and also warns you if you are coming up on one. It has saved my behind a couple of times.

There used to be a site called "Low Clearance POI" that allowed you to download into your GPS, but I just checked it and it seems to be defunct.

If you Google something like "low clearances" you will see some possibilities, I can offer no first hand experience other than the above.

The Motor Carrier Atlas would be a good tool for planning, but less helpful when you are underway, unless your navigator has it open. My near misses were due to either missing a turn or "winging it." The Garmin warned me in time on both occasions.

I use a book, The Motor Carrier's Atlas. It highlights the routes that are recommended for truckers. I've been all over this country for the past 8 years and I've never been turned around by a low bridge.