Process Column falls off of Transporter 2

[StressGuy]

I don't have more detail yet other than the pictures in the article:

350,000 LB Process Column falls off of Transporter

I was really surprised to see this, especially on a straight road as this heavy haul transport is a pretty mature business. The last time I saw anything related to a transporter losing a load, it was trying to make a turn.

There are some comments I've seen from supposed witnesses that the car that got crushed raced around the escort vehicles trying to pass the transporter and ended up colliding with.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[3DDave]

They are all plumbed together, distributing the load. This allows traditional AASHTO calculations to be skipped when supplied with the appropriate analysis. Because they are all joined, at least from front to back, not side to side, when they hit a bump, that one tire group goes up but it also distributes fluid to all the others, causing the shock of the abrupt change to be evened out over the entire trailer.

In our trailers hitting a 4X4 at speed was similar to a conventional trailer hitting a one inch high obstacle. Very advantageous in the warzones it operated as people were around to neaten up bombed out roads and collapsed buildings.

Ours also plumbed the gooseneck to the front set of axles, so the load would also be varied to the tractor, which made trouble for hired tractor drivers as there was also a hydraulic pump to even out the trailer. With the landing gear down and attached to the 5th wheel, the system was capable of lifting the drive wheels off the ground. Failing to get them completely clear of the ground still left the tractor with insufficient traction.

It would not be a problem to handle - simply measure the height of the frame rails before putting the trailer on, then restore that height with the gooseneck to get out from underneath - but drivers for some reason did not do that.

 

[TugboatEng]

If I take a rope and put many hydraulic jacks long it's length and a load in the center, will the ends of the rope transfer any load to the jacks as they hold the rope straight? I don't see enough rigidity in this system to transfer load.

 

[3DDave]

I am rather sure they didn't make the deck out of rope and they didn't make a design that doesn't work.

 

[TugboatEng]

If the design is good why is the column on the ground next to the trailer?

 

[3DDave]

The trailers appear undamaged. What it looks like is there are two groups, fore and aft, and each group has a pivot pin arrangement in the center of the group to allow the groups to turn independently of the load. However the load is so long it might not survive being supported solely on those cradles, at least on the highway, so additional cradles are added farther fore and aft with slide plates to slip back and forth on the deck.

The accident occurred where they were moving from a 4-lane to a 2-lane section of highway, so they would be shifting the groups from the right most lane to the continuation of the left lane.

If the driver of the rear group used only a crabbing motion rather than turning, that could have put the rear slide cradle off the edge of the trailer, pulling the rear side cradle with it, as seen in the photos.

I presume someone thought that making 2 groups would allow more maneuverability getting out of and into the original build site and the final installation site respectively, places where the lack of large loads or harmonic vibrations could allow removal of the slide blocks.

Other places said it took 1.5 lanes and it may be the driver coming the other direction saw the truck come far over the centerline and tried to make it to the open, right, oncoming lane. It's possible the rear driver saw the car and panicked and crabbed to avoid scuffing the tires on the trailer, dumping the tower on the car.

Good job to the police and escorts in closing all access to the road.

 

[XR250]

If I take a rope and put many hydraulic jacks long it's length and a load in the center, will the ends of the rope transfer any load to the jacks as they hold the rope straight? I don't see enough rigidity in this system to transfer load.

I tend to agree. How is there enough stiffness in that slender trailer for that to be effective?

 

[waross]

Possibly the four wheeler clipped the trailer and damaged some hydraulic lines.
That could affect the steering and/or the side to side balance.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[dik]

The hydraulics should be able to accommodate that.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[3DDave]

It's a uniformly loaded beam with a wide support in the middle.

Maybe the thought is they are made as flimsily as OTR trailers usually are?

 

[zeusfaber]

Possibly the four wheeler clipped the trailer and damaged some hydraulic lines.
That could affect the steering and/or the side to side balance.

To be honest, if the overtaking vehicle got itself wrapped up in the transporter's wheels, it would wreak havoc even without damaging the hydraulics. That's pretty much what happened in this other accident.

A.

 

[3DDave]

Chains had been secured to a metal plate which protected brake and electrical hoses.
Mr Hunt described this as "extremely dangerous".
"The reason I say this is that there is nothing to stop the chain moving forward and taking out the hoses".

From the BBC 2008 accident article it seems like the poorly secured vehicle on the trailer was chained to the pneumatic brake lines and damaged the lines when it rolled forward as well as from placing 3 battle tanks onto a trailer that had capacity for 2.

 

[zeusfaber]

Context: These were CVRTs (weighing 7 or 8 Tonne each, on a trailer plated for something like 56T), rather than Main Battle Tanks.

The (allegedly) dodgy lashing - to a plate close to the brake lines, rather than to the brake lines themselves - was actually on vehicles that weren't involved in the accident. A surprising number of people were a bit taken aback to discover that lashing schemes are spec'd to restrain loads during manoeuvring and emergency braking - not to hold everything together throughout a catastrophic series of high speed collisions.

(Allegedly), the taxi driver joined the motorway as the truck was passing, pulled out and began to overtake it, then started searching in his door pocket for a road atlas, discovering too late that he wasn't going where he thought he was. With a taxi caught up in its wheels, the trailer started to go places it wasn't meant to, hit things it shouldn't have and then shed it's load.