CDL General Knowledge Test Emergencies, Skids, Crashes, and Fires Summary

When a tire fails: hold the steering wheel firmly with both hands and stay off the brake unless you are about to hit something. Once the vehicle slows, brake very gently, pull off the road, and check all the tires.

Wrong choices

• Brake hard right away to stop quickly: Braking after a blowout can make you lose control.
• Steer onto the shoulder at full speed: Quick moves at full speed can cause a rollover or skid.

Stopping is not always the safest choice. You can almost always turn to miss an obstacle more quickly than you can stop. But top-heavy vehicles and multiple trailers may flip over.

Wrong choices

• Stop before reaching the obstacle: A large vehicle needs a long distance to stop.
• Both take the same amount of time: Turning is usually quicker than stopping.

At any crash, protect the area (move your vehicle off the road if you can, use flashers, set out triangles), notify authorities, and care for the injured.

Wrong choices

• Move the injured, clean up the road, and leave: Do not move badly injured people unless there is fire or traffic danger.
• Take photos, call your employer, and wait in the cab: Protecting the area to prevent another crash comes first.

Stay as far away as you can, stand upwind, and aim at the source or base of the fire, not up into the flames. Keep going until whatever was burning has cooled.

Wrong choices

• At the top of the flames: Spraying up into the flames does not put out the fire.
• At the smoke: Smoke is not what is burning.

ABS keeps your wheels from locking up during hard braking, which helps you keep steering control. It does not necessarily shorten your stopping distance, and it does not increase or decrease your normal braking power.

Wrong choices

• It always makes the vehicle stop in a shorter distance: ABS does not necessarily shorten stopping distance.
• It lets you follow other vehicles more closely: ABS does not allow you to drive less carefully.

If an oncoming driver drifts into your lane, a move to your right is best. When that driver notices, the natural reaction is to return to their own lane.

Wrong choices

• To the left, into the other driver's lane: The other driver may return to their own lane and hit you head-on.
• Straight, while braking as hard as you can: Hard braking may lock the wheels and you may not stop in time.

Stab braking:

1. Apply the brakes all the way.
2. Release the brakes when the wheels lock up.
3. As soon as the wheels start rolling, apply them fully again. (It can take up to one second for the wheels to start rolling.)

Wrong choices

• Pump the pedal lightly many times without ever locking the wheels: That is not the stab braking method.
• Push the pedal as hard as you can and hold it down: Holding locked brakes causes a skid.

For a cargo fire in a van or box trailer, keep the doors shut, especially if the cargo includes hazardous materials. Opening the doors feeds the fire oxygen and can make it burn very fast. Pull off in an open area and call for help.

Wrong choices

• Open the doors to see what is burning: Opening the doors gives the fire oxygen and makes it burn faster.
• Open the doors and spray water inside: This also feeds the fire with oxygen, and water may be the wrong agent.

ABS helps you keep control and steer during hard braking, and if it fails you still have normal brakes. But ABS will not necessarily shorten your stopping distance, so the statement that it always does is not true.

Wrong choices

• ABS helps you keep steering control during hard braking: This is true. It is the main benefit of ABS.
• If ABS fails, you still have your normal brakes: This is true. ABS is an add-on to normal brakes.

Most front-wheel skids come from driving too fast for conditions. The front end goes straight no matter how you steer. The only way to stop the skid is to let the vehicle slow down: stop turning and/or braking so hard, and slow down as quickly as you can without skidding.

Wrong choices

• Turn the steering wheel even harder: Sharper steering will not help. The front tires have no grip.
• Speed up to regain traction: More speed makes a front-wheel skid worse.