​Losing control of any vehicle is scary. When it’s a large truck, it can be deadly. In heavy traffic it can be fatal if the trailer slides out of control and hits other vehicles on the road. Help your drivers understand the various conditions that cause jackknifing and how to avoid it. 

According to the National Highway Traffic Safety Administration (NHTSA), 10 percent of all fatal truck accidents involve jackknifing. Trucks can jackknife if a driver loses control of the angle between the tractor and the trailer. This can happen when the tractor skids sideways or when the trailer swings out of line with the tractor. Over-braking or skidding trailer tandems can cause the trailer to swing out of line. The tractor typically skids sideways due to the drive wheels spinning from too much power, the drive wheels locking from over-braking during deceleration, or the truck going into a turn too fast and the tires being unable to hold the tractor on course.

More than 90 percent of jackknife accidents involve a tractor pulling a single trailer, with the rest generally involving tractors with multiple trailers, according to the NHTSA. Longer trucks are more likely to jackknife but heavier trucks are less likely. Jackknife accidents are much more likely to occur when the speed limit for trucks is 55 mph or more, when roads are slippery and when trucks have to navigate tight curves. Other causes of jackknifes include unbalanced brake systems, unbalanced and light loads, applying only the trailer brakes, drivers misusing engine retarders when the road is slick, and dirt, oil and grease buildup on roads after long periods without rain.

While braking, especially during hard brake applications, drivers should check their mirrors to see if their trailer is swinging. If it is, drivers should ease up on the brakes and try to correct the angle by steering, but should avoid over-steering. If a jackknife goes beyond a 15 degree angle, it can be almost impossible to correct. Also, the faster the trailer is moving, the harder it will be to correct the situation.

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  • Driving Techniques