General Knowledge: Inspection, Space, Speed, and Night Driving
Colorado's General Knowledge test is the broadest CDL written exam - 50 questions with 80% correct needed to pass - and it covers the core of the CDL manual: inspection, basic control, seeing and communicating, space and speed management, night and mountain driving, emergencies, and cargo. The endorsement tests assume this material, so questions are practical rather than trivia.
Inspection and control
- The most important reason for a pre-trip inspection is safety, not avoiding breakdowns. Check tires, wheels, brakes, lights, fluids, couplings, and cargo securement before moving.
- Start, steer, and stop smoothly; harsh inputs are how skids and cargo shifts begin.
Seeing and communicating
- Look 12–15 seconds ahead - about one city block in town. Scan mirrors every few seconds and before every lane change.
- Signal early and cancel afterward. Use four-way flashers when moving slowly (roughly below 40 mph) or stopped in an emergency; tap the brakes to warn a tailgater.
- At night, headlights are required from sunset to sunrise and whenever visibility is under 1,000 feet. Dim to low beams within 500 feet of oncoming traffic and within 200 feet when following.
Space and speed
- Following distance: one second for every 10 feet of vehicle length at 40 mph or less, then add one second above 40 mph.
- Choose a speed that lets you stop within the distance you can see, and keep an escape route.
Worked example
A 70-foot combination is traveling 55 mph. At 40 mph or less it would need 7 seconds (70 ÷ 10). Because it is above 40 mph, add 1 second: 8 seconds. At 55 mph, 8 seconds is roughly 640 feet - more than two football fields. If the road is wet or the load is heavy, add more.
Mountain and winter notes
- Downshift before a downgrade; do not ride the brakes. If brakes fade, use an escape ramp.
- Colorado's chain law is posted in levels; when Level 2 is called, commercial vehicles must chain up.
Traps
- Using the 40-and-under rule at highway speed and forgetting the extra second.
- Thinking flashers let you drive normally; they are for slow or emergency operation.
- Looking only 2 seconds ahead, or checking mirrors only before turns.
- Treating the pre-trip as a formality - exam questions ask why each check matters.