Space Management and Hazard Perception - Complete Guide

Safe commercial driving requires maintaining space around your vehicle and recognizing hazards before they become emergencies. Sections 2.7-2.9 of the CDL manual cover the space cushion formula, off-tracking during turns, hazard perception, and distracted driving laws—all frequently tested on the CDL exam.

Space Ahead: Following Distance Formula

The space ahead is the most important space around your vehicle.

The 1-Second-Per-10-Feet Rule

At speeds below 40 mph:

1 second of following distance for every 10 feet of vehicle length

At speeds above 40 mph:

Add 1 extra second for safety

Vehicle Length	Below 40 mph	Above 40 mph
40 feet	4 seconds	5 seconds
50 feet	5 seconds	6 seconds
60 feet	6 seconds	7 seconds

How to Measure Following Distance

Watch vehicle ahead pass a fixed point (shadow, sign, pavement marking)
Count: "one thousand-and-one, one thousand-and-two..."
Stop counting when you reach the same point
Compare to rule: 1 second per 10 feet of your vehicle

Key Point: The vehicle ahead can probably stop faster than you. Following too closely is the most frequent cause of rear-end crashes involving trucks and buses.

Space Behind: Dealing with Tailgaters

You can't stop others from following too closely, but you can reduce the danger.

When You're Likely to Be Tailgated

Traveling slowly (going uphill with heavy load)
Bad weather (cars follow trucks because they're easier to see)

How to Handle Tailgaters

Do	Don't
Avoid quick changes	Speed up
Signal early	Flash brake lights at them
Slow down very gradually	Make sudden moves
Increase YOUR following distance	Play games or tricks

Why increase following distance? More room ahead means you won't need sudden stops that could cause the tailgater to hit you.

Space to the Sides

Commercial vehicles are wide and take up most of a lane.

Key Rules

Stay centered in lane—you have little room to spare
Avoid traveling alongside others—they may change lanes into you, or you may be trapped
Strong winds—make staying in lane difficult; worse for lighter/empty vehicles

Space Overhead

Hitting overhead objects is a serious danger.

Critical Points

Issue	What to Know
Posted heights	May be inaccurate due to repaving or packed snow
Empty vs. loaded	Empty vans are HIGHER than loaded ones
Tilted roads	May reduce side clearance for signs, trees, bridges

Exam Trap: Getting under a bridge when loaded does NOT mean you can clear it when empty. Empty vehicles ride higher.

Before Backing

Get out and check for overhead hazards:

Tree branches
Electric wires
Signs
Building overhangs

Space Below

Don't forget clearance under your vehicle.

Problem Areas

Dirt roads and unpaved yards (heavily loaded = less clearance)
Drainage channels across roads
Railroad tracks (especially with low trailers)

Warning: Getting hung up on railroad tracks is extremely dangerous.

Space for Turns: Off-Tracking

Large vehicles don't turn like cars. The rear wheels follow a shorter path than the front wheels—this is called off-tracking.

Right Turns

Rule	Reason
Turn slowly	More time to avoid problems
Keep rear close to curb	Prevents others passing on right
Turn wide as you COMPLETE the turn	Not at the start
Don't swing wide left to start	Driver behind may try to pass on right

Left Turns

Reach center of intersection before turning
Turning too soon = left side may hit other vehicles (off-tracking)
If two turn lanes, take the right turn lane—you may need to swing right

Space to Cross or Enter Traffic

Large vehicles accelerate slowly and need more space.

Need larger gap than a car would need
Allow more room if heavily loaded
Make sure you can get all the way across before traffic reaches you

Hazard Perception

A hazard is any road condition or road user that could become dangerous. Seeing hazards early gives you time to plan and avoid emergencies.

Road Hazards

Hazard	Why Dangerous
Work zones	Narrow lanes, distracted workers, sudden stops
Drop-offs	Can tilt vehicle, hard to steer back onto road
Foreign objects	Tire/brake damage; may contain heavy materials
Off-ramps/on-ramps	Posted speeds may be safe for cars but not trucks

Driver Hazards

Type	Clues
Blocked vision	Rental trucks, loaded wagons, frosted windows
Delivery trucks	Doors/packages block vision; may move suddenly
Parked vehicles	Watch for brake lights, movement, exhaust
Confused drivers	Hesitation, sudden stops, looking at maps
Impaired drivers	Weaving, drifting, wrong-time stopping
Drivers in a hurry	May cut in front of you

Pedestrian/Cyclist Hazards

May have back to traffic
May wear headphones (can't hear you)
Children act without checking traffic
People near ice cream trucks

Distracted Driving Laws

Distracted driving causes approximately 5,500 deaths and 448,000 injuries annually.

Cell Phone Rules (Federal Law)

Prohibited while driving CMV:

Holding phone to conduct voice call
Dialing by pressing more than a single button
Reaching from seated position to get phone

Allowed:

Hands-free phone located within close reach
Single-button dialing
Voice-activated dialing

Cell Phone Penalties

Offense	Disqualification
2nd offense in 3 years	60 days
3rd+ offense in 3 years	120 days
Civil penalty per violation	Up to $2,750 (driver)
Employer penalty	Up to $11,000

Texting Rules (Federal Law)

Completely prohibited:

Manually entering text
Reading text from device
Includes: SMS, email, instant messaging, web access

Texting Penalties

Same as cell phone: 60 days (2nd), 120 days (3rd+), up to $2,750 per violation.

The Statistics

Activity	Crash Risk Increase
Dialing phone	6 times greater
Texting	23.2 times greater

Activity	Eyes Off Road	Distance at 55 mph
Dialing	3.8 seconds	306 feet
Texting	4.6 seconds	371 feet (football field)

Key Point: Hands-free devices are NOT safer than hand-held—they still cause mental distraction.

Frequently Asked Questions

Q: What is the following distance rule for commercial vehicles?

A: One second for every 10 feet of vehicle length at speeds below 40 mph. Add 1 second above 40 mph. A 40-foot vehicle needs 4 seconds below 40 mph, 5 seconds above 40 mph.

Q: How do you measure following distance?

A: Watch the vehicle ahead pass a fixed point. Count seconds until you reach the same point. Compare to the 1-second-per-10-feet rule for your vehicle length.

Q: What is off-tracking?

A: When turning, rear wheels follow a shorter path than front wheels. This causes the rear of the vehicle to cut the corner, potentially hitting curbs, signs, or other vehicles.

Q: Why shouldn't you swing wide LEFT when starting a right turn?

A: Drivers behind may think you're turning left and try to pass you on the right. You may then hit them as you complete your right turn.

Q: Are empty trucks higher or lower than loaded trucks?

A: Higher. An empty van rides higher than a loaded one. Clearing a bridge when loaded doesn't mean you can clear it when empty.

Q: What are the cell phone penalties for CMV drivers?

A: 60-day disqualification for 2nd offense within 3 years, 120 days for 3rd offense. Civil penalties up to $2,750 per violation. Employers face up to $11,000 penalties.

Q: How much does texting increase crash risk?

A: 23.2 times greater risk of a safety-critical event. Texting takes eyes off road for 4.6 seconds average—371 feet at 55 mph.

Q: Are hands-free phones safer than hand-held?

A: No. Hands-free devices still cause mental distraction. Research shows phone conversations reduce brain attention to driving by 39%.

Q: What should you do if you're being tailgated?

A: Avoid quick changes, signal early, reduce speed gradually, and increase YOUR following distance. Don't speed up or flash your brake lights.

Q: When is using a hand-held phone allowed?

A: Only in emergencies to contact law enforcement or emergency services.

Next Steps

Memorize the key formulas and numbers:

1 second per 10 feet + 1 second above 40 mph
Texting = 23.2x crash risk
Cell phone violations: 60/120 day disqualifications

Ready to test your knowledge? Start practicing with our Space Management questions.