How to Avoid Jackknifing

Preventing a Jackknife Situation

To avoid jackknifing, brake before a turn rather than during a turn.
To avoid jackknifing, brake before a turn rather than during a turn.
iStockPhoto/Arpad Benedek

Luckily, even in dangerous conditions, jackknifing isn't inevitable. Preventing jackknife situations takes a few safe driving tips.

The first step in preventing a jackknife situation on the highway is to check your mirrors for trailer swing frequently. You should also do this every time you have to brake hard [source: California DMV]. If you notice that you're already starting to jackknife, it might not be too late to prevent your caravan from bending into an angle of no return. In this situation, experts recommend letting go of the brake which lets the wheel resume rolling and regain the traction of static friction [source: California DMV]. With a trailer jackknife (the trailer wheels lose traction), you can increase your speed to allow the trailer to fall back in line. However, if you are experiencing a tractor jackknife (the tractor wheels lose traction), and you think sudden acceleration could have caused it, let up on the gas pedal until the vehicle regains traction. Then, steer out [source: Byrnes].

In many traffic reports of jackknifing, the trailers are empty. This is no coincidence, and the reason points back to our friction discussion on the last page. The heavier a trailer is, the more it bears down on the road, meaning the more friction it has with the road and the better the traction. Compound this with the fact that over-braking is easier on light loads (because the brakes of a tractor-trailer are made for fully-loaded trucks), and it turns out that empty trailers are more prone to jackknifing [source: Pellerin]. So, although it might seem counterintuitive, you should watch mirrors for trailer swing, particularly when driving an empty trailer.

Proper braking is another essential. Instead of braking during turns, decelerate slowly on the long stretch before the bend or curve. Avoid slamming on the brakes, which could cause them to lock and will often result in a jackknife situation. Although, at times, there may be no alternative to hard braking, you can do your best to stay out of these situations. One way is to keep a safe distance from other vehicles on the road. When an emergency situation occurs, do your best to avoid braking and swerving at the same time. This might mean braking, letting go of the brake, swerving and then braking again [source: Wiley and Terrell].

It's important to note that jackknifing isn't a problem just for truckers -- drivers inexperienced with towing often set out on the highway with a trailer or a boat and end up losing control from heavy braking or other factors. For instance, an improperly balanced trailer with a rear-heavy load tends to sway and can cause the trailer to swing out into a jackknife [source: Kazmierski]. To avoid this, make sure to pack your trailer with weight spread out and on the bottom, giving it a low center of gravity.

However, the novice trailer-tower is even more likely to get stuck in a jackknife position when backing up. This kind of jackknifing has less to do with traction and more to do with knowing how to handle a trailer in reverse. One handy trick is to place your hand at the bottom of the steering wheel, or six o'clock position. While turned around to see where you're going, move your hand in the direction you want the trailer to go [source: Popular Mechanics].

Although these tips will help you as a driver, it's hardly comforting if you're concerned the driver of the enormous 18-wheeler beside you doesn't know them. Fortunately, we can take a little comfort in the development of sophisticated anti-jackknife technology, which has helped combat driver error.