Following distance — memorize this exactly
Illinois CDL uses a heavy-vehicle formula, not simply the regular-car 3-second rule:
At speeds UNDER 40 mph:
1 second for every 10 feet of vehicle length.
At speeds OVER 40 mph:
Use the same formula PLUS 1 additional second.
Vehicle length Under 40 mph Over 40 mph
30 ft 3 sec 4 sec
40 ft 4 sec 5 sec
50 ft 5 sec 6 sec
60 ft 6 sec 7 sec
You’re driving a 40-foot bus at 35 mph. How much following distance?
➡️ 4 seconds.
40-foot bus at 50 mph?
➡️ 5 seconds.
And if the road is slippery, Illinois says you need more space to stop, so increase your following distance.
🚗 If someone is tailgating YOU
Illinois says:
* Don’t speed up.
* Avoid quick changes.
* If you need to slow/turn, signal early and reduce speed gradually.
* Increase your following distance so you don’t have to make sudden changes.
* Don’t try to “teach” the person behind you a lesson by flashing your brake lights or doing tricks.
🛑 And here’s an important stopping-distance number
For an air-brake vehicle traveling 55 mph on dry pavement, the manual says air-brake lag adds about 32 feet, and total stopping distance for an average driver under good conditions is over 450 feet.
The manual’s example gives 451 feet at 55 mph.
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And YES, this is exactly how I should make the rest of your study sheet: not “drive carefully,” but the actual numbers/rules you’ll need to recognize on the test.
The manual asks: How far ahead should you look?
➡️ 12–15 seconds ahead.
At highway speed, that is roughly one block in the city or about ¼ mile on the highway.
You should look for:
* Traffic
* Pedestrians
* Road conditions
* Traffic signals/signs
* Vehicles entering your path
* Other hazards
🚗 Following distance
For a large vehicle:
Under 40 mph:
➡️ 1 second for every 10 feet of vehicle length.
Over 40 mph:
➡️ Add 1 additional second.
Example:
40-foot bus at 35 mph = 4 seconds
40-foot bus at 50 mph = 5 seconds
This is one you should MEMORIZE.
🛑 Stopping distance
The manual breaks stopping distance into:
Perception distance + reaction distance + brake lag + braking distance = total stopping distance.
At 55 mph, the Illinois manual’s example gives:
* Perception: 142 ft
* Reaction: 61 ft
* Air-brake lag: 32 ft
* Braking: 216 ft
* Total = 451 ft
That’s under good traction/braking conditions for the example.
⚠️ Speed
There isn’t a rule like “always reduce to 20 mph when visibility is X.”
Instead, the manual says you must choose a speed that is safe for:
* Your vehicle
* Road conditions
* Weather
* Traffic
* Visibility
* Curves
* Grade
For downgrades, never exceed a posted speed limit or a posted Maximum Safe Speed. Use the engine’s braking effect as the principal way of controlling speed and select a low gear before starting down the grade.
🌧️ Bad weather / visibility
Reduce speed for adverse weather or road conditions.
In work zones, the manual specifically says to:
* Obey the posted work-zone speed limit.
* Watch your speedometer.
* Reduce speed for bad weather/road conditions.
* Reduce it even further when a worker is close to the roadway.
So don’t memorize a made-up “visibility = X mph” rule—the Illinois CDL manual does not give you one universal number.
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SECTION 3 — TRANSPORTING CARGO
⚖️ Class B
26,001+ GVWR = Class B.
A Class B vehicle can tow a vehicle with a GVWR of 10,000 lbs or less.
Cargo
Remember:
Cargo must be secured so it cannot:
* Shift
* Fall
* Leak
* Affect vehicle control
For your bus, this mostly translates into knowing how passengers/baggage and any other carried items must be kept secure.
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SECTION 4 — PASSENGER
For your bus goal, study this heavily.
🚍 CDL passenger threshold
A vehicle designed to transport 16 or more people, including the driver, requires a CDL.
Passenger endorsement
For Illinois Class B:
Passenger (P) = Section 4.
Illinois lists Passenger as an optional endorsement for Class B and C, with written and skills/drive testing.
Know:
* Passenger loading/unloading
* Emergency exits
* Aisles
* Seating
* Baggage
* Doors
* Evacuation
* Passenger safety
* Railroad crossings
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SECTION 5 — AIR BRAKES
Since you’re going for the bus route, I would learn these numbers.
💨 Air pressure
Before driving a vehicle with a dual air system:
➡️ Build air pressure to at least 100 psi in BOTH systems.
🚨 Low-air warning
The warning light/buzzer must come on before air pressure drops below 60 psi in either system.
If that happens while driving:
➡️ Stop immediately and safely park.
Those are very important numbers.
🛑 Air-brake lag
At 55 mph on dry pavement:
➡️ Air-brake lag adds approximately 32 feet.
Total stopping distance in the manual’s example:
➡️ 451 feet.
⛰️ Long downgrade braking
Once you’re in the proper low gear:
1. Apply brakes enough to feel a definite slowdown.
2. When you’re about 5 mph below your safe speed, release the brakes.
3. That application should last about 3 seconds.
4. When speed rises back to your safe speed, repeat.
🔥 5 mph + 3 seconds = memorize it.
ABS
ABS does NOT mean:
* Drive faster ❌
* Follow closer ❌
* Drive less carefully ❌
It helps maintain control and prevent brake-induced wheel lockup. It does not necessarily shorten stopping distance.
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SECTION 10 — SCHOOL BUS 🚌
Since you’re actually driving school buses, this section matters a lot.
🚨 Danger zone
The school-bus danger zone can extend:
Up to 30 feet in front of the bus.
The first 10 feet in front is the most dangerous.
Also:
10 feet to the left
10 feet to the right
10 feet behind the rear bumper
And the left side is always considered dangerous because of passing traffic.
👀 Mirrors
The Illinois manual’s diagram shows:
200 feet of coverage to each side in the mirror illustration.
It also notes that a blind spot can be approximately:
50–150 feet.
🔥 Those numbers are worth memorizing.
School Bus endorsement
Illinois requires:
P + S
for a CDL driver operating a yellow school bus to transport school students.
The S endorsement requires:
* Passenger written test
* School Bus written test
* Skills/drive testing in the proper school bus
And an Illinois School Bus Permit (SBP) is also required for school transportation covered by the state rules.
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SECTION 11 — CHARTER BUS
Here’s something important because you told me they specifically told you to study 10–14.
Illinois has a Charter Bus (C) endorsement.
But it has a very specific purpose: a bus other than a school bus that is chartered by a school to transport students in grade 12 or below to/from a school-sponsored activity.
So for studying, focus on:
* Passenger safety
* Loading/unloading
* Emergency exits
* Baggage
* Emergency procedures
* Bus inspection
* Passenger management
But don’t confuse Charter Bus C with the regular CDL Class C license.
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SECTION 12 — PRE-TRIP
🔥 THIS IS NOT JUST A WRITTEN-TEST SECTION.
It’s part of your actual CDL skills testing.
Illinois says the CDL drive test has:
1. Pre-trip inspection — Section 12
2. Skill maneuvers — Section 13
3. Driving road test — Section 14
For your bus, learn how to identify/check:
Engine area
* Leaks
* Belts
* Hoses
* Fluid levels
* Steering components
Wheels/tires
* Inflation
* Tread
* Damage
* Lug nuts
* Rims
Suspension
* Springs
* Mounts
* Air suspension components where equipped
Brakes
* Lines/hoses
* Chambers
* Slack adjusters
* Drums/discs
* Damage
Lights
* Headlights
* Brake lights
* Turn signals
* Clearance/marker lights
* Four-way flashers
Emergency equipment
* Fire extinguisher
* Warning devices
* Required equipment
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SECTION 13 — BASIC CONTROL
Your big focus:
Straight-line backing
Keep the vehicle straight while backing.
Offset backing
Move the vehicle backward while controlling the path into the required position.
General rule
Slow = control.
Use:
* Mirrors
* Looking around
* Steering corrections
* Stop-and-check when necessary
Don’t rush the maneuver.
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SECTION 14 — ROAD TEST
This is where they watch how you actually drive.
Know how to perform:
Turns
* Signal
* Check mirrors
* Correct lane
* Proper speed
* Watch rear wheels
Lane changes
➡️ Mirror → signal → check → move
Intersections
* Check traffic
* Pedestrians
* Signals/signs
* Proper stopping position
Railroad crossings
* Follow the applicable passenger/school-bus procedure.
Stopping
* Controlled
* Smooth
* Complete
* Correct location
Speed
* Never exceed the posted limit.
* Adjust speed for conditions.
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⭐ YOUR NUMBERS TO MEMORIZE
Put this somewhere you can look at it every day:
Topic Number
Class B 26,001+ GVWR
Class B towing 10,000 lb or less
Following distance 1 sec / 10 ft under 40 mph
Over 40 mph +1 second
Look ahead 12–15 seconds
Air system before driving 100 psi minimum
Low-air warning Before 60 psi
Air-brake lag @ 55 mph 32 ft
Total stopping example @ 55 mph 451 ft
Downgrade braking cycle 5 mph below safe speed / ~3 sec
School-bus danger zone front up to 30 ft
Front most-dangerous area first 10 ft
School-bus side danger zones 10 ft each side
School-bus rear danger zone 10 ft
Mirror diagram side coverage 200 ft
Possible blind spot 50–150 ft
Passenger CDL threshold 16+ including driver