Illinois CDL Permit Test - Double

Hydroplaning is similar to water skiing: your vehicle's tires glide along the road on a film of water without having traction with the surface of the road.

If a trailer begins to jackknife, you should release the brakes and allow the trailer wheels to regain traction with the road. Do not apply the trailer hand brake in an attempt to straighten out the rig because it will only prolong the skid. The application of brakes is what caused the wheels to lock in the first place.

When driving a combination vehicle, it is important to brake well in advance and look far ahead of your vehicle to avoid the need for sudden stops. Making habits of these actions will help you prevent your trailer from jackknifing.

While driving, you should continually scan the road to spot potential hazards in advance. Make emergency plans for how to deal with the hazards if they become dangerous.

Passing an accident scene can be hazardous because the people involved in the accident may not be watching traffic, and the scene itself may distract other passing drivers. Ice cream trucks can create hazardous conditions because they attract children who may not pay attention to nearby vehicles. Shoppers near the roadway are often paying attention to stores, not passing traffic.

An empty trailer will require a longer stopping distance than a loaded trailer. Additionally, a trailer is most likely to swing out and strike other vehicles when it is lightly loaded or empty.

On a downgrade, the braking effect of the engine should be your primary method of controlling speed. Shift down to a lower gear before starting down the hill and save the brakes for additional slowing or stopping that may be required by road or traffic conditions.