Study guide
Most emergencies announce themselves early to drivers who know what to look for, and the ones that do not can still be survived with the right trained response. This chapter covers reading hazards before they mature, the federal rules on phones and distraction, emergency steering and brake failure, skid control and ABS, and the crash, fire, and fitness-to-drive knowledge every general knowledge exam samples.
Seeing Hazards Before They Become Emergencies
A hazard is any road condition or road user that presents a possible danger. The skill the manual teaches is spotting hazards while they are still only possibilities, because recognition time is the cheapest safety margin you will ever get. Learn the standard clues. Work zones mean narrowed lanes, pavement drop-offs, workers near traffic, and drivers watching the work instead of the road. Objects on the roadway — even boxes or bags that look empty — may contain something heavy, and are worth avoiding without a violent swerve. On-ramps and off-ramps mean sudden speed changes and drivers cutting across lanes to make an exit. A disabled vehicle on the shoulder means a person who may step into traffic; a jacked-up wheel or raised hood is the tell. Around parked vehicles, look for brake lights, exhaust, and front wheels turned outward — evidence someone is about to pull out. Children, ice cream trucks, and pedestrians talking or looking at phones all mean movement that ignores traffic. Read other drivers, too: a turn signal left blinking for a mile means the driver does not know it is on, and a signal that contradicts the vehicle's position means trust the vehicle, not the signal. Slow, hesitant drivers and rental trucks suggest confusion; weaving, drifting, and lane-straddling suggest impairment, especially late at night. None of this requires fortune-telling. It requires a running plan the manual sums up as leaving yourself an out: at every moment, know where you would steer and how you would shed speed if the possible hazard became a real one two seconds from now.
Distracted Driving, Phones, and Aggressive Drivers
Distraction is anything that pulls your eyes, hands, or mind away from driving, and at commercial speeds a few seconds of it consumes several hundred feet of road. Plan distractions out of the trip: set the GPS, review the route, and adjust mirrors, seat, and climate controls before the wheels move, and eat before or after driving, not during. The federal rules for commercial drivers are strict and heavily tested. Texting while driving is banned, and texting is defined broadly: manually entering or reading text, including email, instant messages, web browsing, and pressing more than a single button to start or end a phone call. Hand-held phone use is banned as well — you may not hold the phone, dial it, or reach for it anywhere that takes you out of your seated, belted driving position. Hands-free use is permitted when the phone is mounted or close enough that a single button press or voice command does everything. Violations carry federal fines that can run into the thousands of dollars for drivers, with far larger penalties for employers who require or allow violations, and a second and third conviction within three years disqualifies a CDL holder for 60 and 120 days respectively. Many states add penalties of their own. The manual pairs distraction with aggression because both are self-inflicted. Aggressive driving means operating in a selfish, pushy, or impatient way that disregards others; road rage escalates that into using the vehicle or a confrontation as a weapon. Protect yourself from both sides of it: leave early so delay never becomes anger, refuse to challenge or block aggressive drivers, avoid eye contact, give them room to go be someone else's problem, and report genuinely dangerous behavior when you can do so safely.
Emergency Maneuvers: Steering, Brake Failure, and Blowouts
Stopping is not always the safest response to an emergency, because you can almost always turn to miss an obstacle more quickly than you can stop for it. That is why the manual insists on keeping both hands on the wheel — an unexpected swerve with one hand on the wheel usually ends in a ditch. When you must steer to avoid a crash, do not brake while turning sharply, do not turn any more than needed to clear the hazard, and be ready to countersteer — turning back the other way — the instant you are clear, because a vehicle that swerves and never straightens has only traded one crash for another. Leaving the pavement can be safer than a collision: most shoulders will carry a heavy vehicle, so if you must leave the road, avoid braking until your speed is down to about 20 mph, keep one set of wheels on the pavement if you can, and return with a deliberate sharp turn plus countersteer rather than trying to edge back gradually. If your hydraulic brakes fail, work the problem in order: downshift to let the engine slow you, pump the brake pedal to build pressure back, apply the parking brake while holding its release so you can modulate it, and look for an escape route — a side road, an open field, an uphill grade. A tire blowout announces itself with a bang, a thumping sound, or steering that suddenly feels heavy or pulls hard. The trained response feels wrong and saves you: grip the wheel firmly, stay off the brake, ease off the accelerator, and brake only after the vehicle has slowed and stabilized.
Skid Control, Recovery, and ABS
A skid happens whenever the tires lose grip on the road, and drivers cause most skids one of four ways: over-braking, over-steering, over-accelerating, or simply driving too fast for conditions. The most serious for a commercial driver is the drive-wheel braking skid, where the rear wheels lock and slide. On a straight truck or bus the rear can swing around; with a tractor-trailer, the trailer keeps pushing the locked tractor wheels sideways into the fold-up crash called a jackknife. To correct a drive-wheel braking skid, stop braking so the wheels can roll and grip again, then countersteer as the vehicle swings back — quickly, because the correction happens fast. Front-wheel skids usually come from driving too fast, and they feel different: the vehicle plows straight ahead no matter how you steer. The only cure is to let the vehicle slow down; steering harder does nothing. The manual also distinguishes two braking techniques. Controlled braking means applying the brakes as hard as possible without locking the wheels. Stab braking — apply fully, release when the wheels lock, reapply when they roll again — belongs only to vehicles without antilock brakes. ABS, the antilock braking system, is a computer that senses impending lockup and modulates the brakes for you, helping you keep steering control during hard braking. Know exactly what ABS does not do: it does not shorten your stopping distance, does not let you drive faster or follow closer, and does not change how you brake. With ABS, brake exactly as you would without it, and watch for the yellow ABS malfunction lamp on the instrument panel during your inspection.
Crashes, Fires, Alcohol, and Staying Fit to Drive
At a crash scene, the manual gives three duties in order: protect the area, notify authorities, and care for the injured. Protect the area first, because a second vehicle plowing into the scene makes everything worse — move your vehicle aside if it is drivable, turn on the flashers, and set out warning devices. When helping the injured, do not move a severely hurt person unless fire or passing traffic makes staying more dangerous; stop heavy bleeding with direct pressure and keep the person warm until help arrives. Vehicle fires each have a signature response. Engine fire: shut off the engine and do not open the hood — aim foam through the louvers or from underneath, because lifting the hood feeds the fire air. Cargo fire in a van or box trailer: keep the doors shut for the same reason. Electrical and fuel fires: never use water; use a B:C rated extinguisher. A tire fire is the exception — it needs large amounts of water to cool the rubber or it will reignite. Park away from buildings and traffic before fighting any fire, and do not fight one you cannot contain. Finally, fitness to drive. Under federal standards it is illegal to operate a commercial motor vehicle with a blood alcohol concentration of 0.04 percent or more — half the common 0.08 passenger-car limit — and any detectable amount of alcohol puts a driver out of service for 24 hours. Illegal drugs and stay-awake stimulant pills are forbidden, and prescription medicines count if they impair. Fatigue crashes cluster in the early-morning hours, and the only genuine cure for sleepiness is sleep — not coffee, cold air, or loud music.
Key terms
- Hazard
- — Any road condition or road user that presents a possible danger, worth planning for before it becomes an emergency.
- Leaving yourself an out
- — The habit of always knowing where you would steer and how you would slow if a potential hazard turned real.
- Distracted driving
- — Any activity that takes eyes, hands, or attention away from driving, including phone use, eating, and adjusting devices.
- Road rage
- — The escalation of aggressive driving into using a vehicle or confrontation as a weapon against another road user.
- Countersteering
- — Steering back in the opposite direction after an evasive turn or skid correction to bring the vehicle straight.
- Controlled braking
- — Braking as hard as possible without locking the wheels, keeping steering ability during a hard stop.
- Stab braking
- — Fully applying the brakes, releasing when wheels lock, and reapplying when they roll — used only on vehicles without ABS.
- Antilock braking system (ABS)
- — A computer-controlled system that prevents wheel lockup during hard braking; it does not shorten stopping distance.
- Drive-wheel braking skid
- — A skid where locked rear wheels slide, which can swing a straight vehicle around or jackknife a tractor-trailer.
- Jackknife
- — The folding of a tractor and trailer toward each other when drive or trailer wheels lose grip and slide.
- Blood alcohol concentration (BAC)
- — The measure of alcohol in the blood; 0.04 percent or more while operating a commercial vehicle is a disqualifying offense.
- Fatigue
- — Physical or mental tiredness that slows perception and reaction; sleep is the only real remedy.
Exam tips
- A recurring answer pattern: you can almost always turn to avoid a hazard more quickly than you can stop for it, and stopping is not always the safest action.
- ABS questions nearly always test the same trap — ABS does not shorten stopping distance, so with ABS you brake exactly as you normally would.
- For a tire blowout, the tested sequence is hold the wheel firmly, stay off the brake, ease off the accelerator, and stop only after the vehicle slows.
- Know both alcohol numbers: 0.04 percent BAC is the commercial disqualification standard, and any detectable amount puts a driver out of service for 24 hours.
- The federal texting definition includes pressing more than one button to place a call — a single button press or voice command on a mounted phone is the only compliant phone use while driving.