Low bridges question

Yes you can usually dump the air from the trailer suspension, it all depends on the trailer tho. Actually it's good practice to dump the air everytime you go to a dock as the shippers usually like it better as the trailer will bounce less when they drive on.
As to how to dump the trailer air, it all depends on the setup of the trailer. Some trailers have had valves on them (usually by the landing gear or the tandems) that you can use to dump the air. Some trailers are automatic however and can only be operated with the dash valve. In which case there wouldn't be much you could do as the trailer spring brakes would come on as well.

Hope that helps.

 

my international when i engage the "air dump" switch, dumps tractor and trailer.

 

The height of a 13' 6" can vary by the height of the tractors 5th wheel. Usually the tallest part of a trailer is actually at the tail. Many trucks have made it under a 13' 6" bridge only to rip off the back doors at the top. Going under with an empty trailer at a high speed can also cause the trailer to bounce up and strike the under side of an overpass.

 

I'm surprised that a bridge that low would allow trucks to travel on it. Never take the sign for the truth. You never know if the sign was replaced when they repaved the road or any other situation that might change the clearance. I'd only go under that low of clearance if it was the very last option I had. And then I creep along and if possible have someone outside watching.

 

Ok, I'll be the one to say it: did you check the route first with your map? If I have questions when I see something like this on a route I have never taken, I have:
Called the county sheriff office and asked about truck routes
Called local T/S and asked the fuel desk
Called dispatch
Called local police station
I have done all these things and they can sometimes keep you from getting into a bind. But one time I called the sheriff and they re-routed me into another low bridge....creative backing (while cussing up a storm) got me fixed. Was late, but called the receiver and they waited. One time I called 9-1-1 to get an escort backing into an intersection, up a hill and around the corner; just to get turned around from a low bridge (my mistake in following directions). And what happened? The cop sent me up a hill (residential) from where I couldn't make a sharp turn (no way). Had to back down around corners; don't want to do that again.
I've learned my lesson: route planning is very, very important.

 

Typically, most bridges are marked lower than they actually are.

There's always the chance they are exactly what they say, or lower LOL.

It's always a good idea to approach any low bridge slowly to verify it. But you can't always do that.

Regardless of what the sign says. Pucker factor should always determine the amount of caution. If it's low enough to cause your cheeks to suck the seat. It's low enough to slow down and check it...even if traffic backs up.

 

I've found the local fire department can help the most.