weight restrictions

Most of the limited weight bridges that I cross when I'm heavy are so short that They'll never have the full weight of the truck and trailer on them anyway but when I was pulling "super trains" in Nevada a few years ago and grossing 129,00 pounds there was a long rickety bridge on a road going into one of my shippers that had a 40 ton weight limit on it and you would regularly see two trains crossing it at the same time...That's 129 tons on a 40 ton weight limit bridge so it's only 89 tons over the posted limit.
I ran that bridge that way for 5 years and it never fell down so....I guess I'm just gonna have to worry about something else!

 

If you are concerned about either damaging or going through the bridge then crawl across the bridge # 15 mph. At that speed there is no suspension bounce thus no weight compounding.

 

Alot of these rural bridges have no advance warning and no turn around. The gov't is at fault for this. What are you expected to back up 2 miles to a turn around? The same goes with some restricted roads. They put the signs on the restricted road itself, so you don't see it until you turn. How about giving me advance warning and put the sign on the road I'm coming off of?

There is a standard formula used to calculate the weight limit. The formula has nothing to do with the strength of the I-beams or concrete strength. So the real true strength of a bridge can be inaccurate. The formula was created in 1964. Alot has changed since then, better stronger materials and better designs. You also have to consider multiple vehicles on a bridge like two opposite direction trucks crossing the bridge at the same time. Two legal trucks crossing has to be considered to not do damage or the formula is useless.

http://en.wikipedia.org/wiki/Federal_Bridge_Gross_Weight_Formula

Like W9 said, alot has to do with weight to length ratio. A loaded dump truck will put alot more stress on a bridge verses a 53' trailer. So most likely there won't be any damage. Over time cracks might develop. The overall lifespan of the bridge is reduced.

So do you back up two miles? Do you stop and cry? Do you gas on it?
The answer is obvious.

I've had PC miler through our fuel desk route me across numerous rural restricted bridges tha have no advance warning. I'll usually communicate back and tell them that routing is bad.

One good example is the shortcut off I-81 in VA going into PA. 7, 340, 15. Many trucks use that route. But when you are on 340 and cross the Potomac River, that bridge is restricted to 65,000. Yet you'll see multiple trucks on it at one time. My first time across was my first restricted bridge crossing. There is no advanced warning, I crossed it and even passes an opposite direction cop. I had the willies ,but nothing happened.

Then one day I had to pick up at a shipper. One way in and one way out. You had to cross a 65,000 lb small bridge going in. There sat a DOT cop right beside the bridge. Legal going in, Illegal coming out. Three of us sat there two extra hours until he left.
They told me that cop done that all the time.

 

If a bridge is going to collapse, it will crack and crack for seconds before it gives. I'm getting off it as quick as posssible. It can collapse behind me.

 

You will put LESS force on the bridge br crawling across it...do I need to draw you a picture?

Come onto a weak bridge # 60 mph and you may go through it. Come onto the same bridge # 15 mph and you have substantially greater chance of crossing it.

 

My understanding of it is that you are right.... as long as you cross at a really reduced speed, and your trailer bridge is not more than 41' you should be OK with the bridge in most cases. However understand that if it is a long wood bridge I would not cross it. a short creek bridge where you would only have either the tractor or trailer wheels on the bridge at any one time..... Neither would exceed the bridge limit. Long concrete bridge use your best judgment based on the appearance of the bridge... IF IN DOUBT DO NOT DO IT.

 

Your idea is good as the truck isn't bouncing. If it's that bad, it's going down regardless. But a concrete bridge would crack and crack and crack before it gave. I wouldn't give it time.

Up and down hills weight shifts around 3000 lbs. which compared to 80,000 lbs isn't much. I wouldn't go on a bridge in that shape.

See you on the other side. I'll help you out of the water

 

don't know for certain about bridges, but I have heard pavement engineers say that the faster you go, the less stress it is on a roadway.