Low Underpasses

Trucks and trailers are 2-3" or more under 13'6" so that they clear Bridges and overpasses that actually measure 13'6". Many 13'6" overpasses are actually over that height. Put your truck and trailer on level ground and measure from the top of the trailer (which sits higher than your truck) to the ground if you don't believe me. Engineers do sometimes do things right.

I still don't recommend going under anything marked less than 13'6" for the reasons already listed.

Interesting.

My first trip on the Maine Turnpike I almost stained my shorts when Zi saw a sign sing 13’ 6” clearance. I thought, is it 13’ 6” exactly, or does that mean a 13’ 6” trailer will clear?

Then I thought, it’s an interstate highway, surely my trailer will clear. I still slowed down to 45, as if that would have helped if it didn’t clear. LOL

I would have ducked, too. That has always helped me on the ones I think look low. I haven’t topped a trailer yet using that technique.

Downtown St. Louis there is an underpass marked (IIRC, it's been a while) 13'6. It was evening, I got turned around on the directions, I was new, and it looked low. I got up closer to it, it looked even lower, so I stopped and GOAL. First thing I saw was scrape marks all over the bottom of the beams and rivets. NOPE!!! I backed up quite a ways (seemed like a mile) to make a turn onto a side street and get the heck outta there and find a different route.

Definitely a tell tale sign is scrapes and gouges on the overpass and skidmarks on the pavement.

Definitely a tell tale sign is scrapes and gouges on the overpass and skidmarks on the pavement.

The pavement would not be the only place skidmarks showed up, if you get my drift

Then I thought, it’s an interstate highway, surely my trailer will clear. I still slowed down to 45, as if that would have helped if it didn’t clear. LOL

Grumpy slowing down in this Instance was a great idea. However, did you know you can also make it under a low bridge by going FASTER? you may lose part of the trailer but at least you'll get to the other side.....just joking. It's something my instructor at school always asked when we had to inform him of low bridge sign (prepping for exam). "How tall is bridge? How tall are you? If that bridge is 11'5 how fast do you need to go to make it through?"