Jacknifed tractor trailers

Living just outside New York City, I hear commuter traffic updates throughout the morning on the radio. Frequently, there’s a report of a jacknifed tractor trailer causing delays.

Does the act of jacknifing cause immobility in a tractor-trailer, requiring special equipment, or is the delay simply because maneuvering a big, honking vehicle like back into its proper state time-consuming and space-occupying?

Any truckers out there? Highway patrol cops? Someone who watched such a scene from his/her office window?

I think they tend to end up in ditches, cause other accidents and/or end up facing the wrong way. Also a friend of mine owns a company that has 10 or 20 tractors (and about twice as many trailors). He recently told me that one of his drivers jackknifed a semi and in the process totaled the trailor. I’d imagine it bends the frame out of shape and messes with the part that hooks into the trailor. I could also see tire damage being a result. I think they had to use a crane to get the tractor out and then he sent a new tractor to go and take the trailor to it’s destination.

The term jackknifing is used in a lot of accidents, not just when the truck alone is responsible for traffic slowdown. A jackknifed truck is usually the least of the problems because a jackknifed truck is one that has gotten out of control and has probably caused other damage.

But in the case of a jackknifed truck alone, the tractor and/or trailer linking mechanism (the fifth wheel) is damaged. Special equipment has to be used. If there is no damage, (not likely but I can provide no cites,) and the tractor can move without damaging anything then it takes a long time to straighten things out.

“Just give me forty acres and I’ll turn this rig around” Country and Western song.

Here’s the same thing said differently:

Under some conditions a truck can easily go into a skid.
If the truck is going straight, it’s possible the tractor
and trailer will stay straight and, possibly, no damage
will occur. This is unlikely. Most likely one set of
axles will begin to skid before the others, that axle will
have less traction than the others, and most likely the
rig will not stay straight.

If the steering axle locks, the tractor may still remain
straight, as the front wheels are sliding and the rest
are holding traction. The driver has little steering control.

If the rear tractor axle locks (the axle in the middle
of the rig) most likely the rear axle will begin to
rotate around the kingpin causing a tractor jackknife.

If the trailer axle locks (the last axle in the rig)
the loss of trailer traction will probably rotate around
the kingpin and cause a trailer jackknife.

All of these result in a loss of control and probable
accident. If the load shifts on the trailer, everything
gets worse. A liquid load is always shifting, so pulling
a tank with liquid can be interesting.

Of course, all the axles can lock, also causing a
jackknife. Most rigs have anti-lock brakes, nowadays.