Clearance Under Bridge

I have read somewhere (maybe here or another site) that you can't always trust the markings on bridges for how much clearance there is to the street. Reasons being, road may have been repaved, snow, GPS not accurate, etc.

If you can't be sure of clearance, how do you know when it is safe to go under a bridge?

Clearances can be a tricky subject as there are many variables. While you are correct that repaving of the road or other construction may have shortened the clearance, it is also a good thing to remember that along the right-most edge of the roadway (or extreme left in the case of arch support bridges) is the lowest point of bridge clearance. Sometimes, unfortunately not all, clearance signs are indicating this lowest point but I personally don't trust it.

It is imperative that you know the maximum height of your vehicle then add a "fudge" factor for different things such as repaving of the roadway. Personally, I use 8" as my "fudge factor", I've talked to others that use 10" or even 6". My primary rule regarding clearances of this sort...when in doubt - find a way around. Safety factor over-rules all.

At CRST, we have routes into NYC that tell us to go under low marked over passes. I have not driven those, but my co driver did with his trainer. My understanding is, they are marked to allow snow pile up. But...... those are specific routes that our company knows are safe. Once early in our co driving, my co driver took a bad turn and came up on an over pass in PA that was marked 12' 9". And it was after a sharp turn, where we would have had to have called for help to back out. On one side, there was a small sign that said "Actual clearance 13 ' 7" ". e went through, but still had a harrowing drive along the Delaware river with rock walls, leaning power poles and narrow traffic lanes. Bottom line is, we lucked out.

We also delivered once into NJ with a specific route in that was safe. 4 lane road and an over pass at 14'5" clearance. Well we delivered, and had no route out. So we thought the way we came in should be safe. Same road, out bound, same overpass had a clearance of 13 3. But on the extreme right side in the emergency lane, had a small sign that said clearance 13' 6". We took it with me driving, and my co driver out spotting to make sure, got back on the interstate , and said a lot of bad words.

Never be afraid to call the police to help you get backed out safely. They would rather help you back out and block the road for you than do paper and reports saying you hit something. I have had to back out of some areas that could not be turned around on. One time I was going to a winery for a load of wine and the roads were super narrow. Finally I needed up having to call the police and I had to back up 5 miles back down the road I was on and make a sharp right on to an even smaller dirt road to get to the winery.

Thank you all for your response. Guyjax, I would not have thought to call police for help out. Thanks.