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Speed & Space Management

5 free sample questions of the 40 in this topic. The full set is in the app.

  1. Question 1

    Total stopping distance equals:

    • A.Perception distance + reaction distance + braking distance
    • B.Reaction distance + braking distance only
    • C.Braking distance × 2
    • D.Vehicle length × speed
    Show answer & explanation
    Answer: A. Perception distance + reaction distance + braking distance

    Three pieces add up: the distance traveled while your brain recognizes the hazard, the distance while you move your foot to the brake, and the distance the brakes take to stop the vehicle.

    Source: California Commercial Driver Handbook (DL 650) — §2.6.1 — Stopping distance

  2. Question 2

    The average perception time for an alert driver is about:

    • A.1/4 second
    • B.3/4 second
    • C.1 3/4 seconds
    • D.3 seconds
    Show answer & explanation
    Answer: C. 1 3/4 seconds

    An alert driver averages 1¾ seconds of perception time — at 55 mph that's 142 feet traveled before you even react.

    Source: California Commercial Driver Handbook (DL 650) — §2.6.1 — Perception distance

  3. Question 3

    At 55 mph on dry pavement with good brakes, braking distance alone is about:

    • A.61 feet
    • B.142 feet
    • C.216 feet
    • D.419 feet
    Show answer & explanation
    Answer: C. 216 feet

    Braking distance at 55 mph runs about 216 feet — on top of 142 feet of perception and 61 feet of reaction distance.

    Source: California Commercial Driver Handbook (DL 650) — §2.6.1 — Braking distance

  4. Question 4

    At 55 mph, your total minimum stopping distance is about:

    • A.219 feet
    • B.319 feet
    • C.419 feet
    • D.519 feet
    Show answer & explanation
    Answer: C. 419 feet

    Perception (142') + reaction (61') + braking (216') ≈ 419 feet at 55 mph — well over the length of a football field once you're at 60.

    Source: California Commercial Driver Handbook (DL 650) — §2.6.1 — Total stopping distance

  5. Question 5

    When you double your speed from 20 to 40 mph, your braking distance becomes:

    • A.Twice as long
    • B.Three times as long
    • C.Four times as long
    • D.Unchanged
    Show answer & explanation
    Answer: C. Four times as long

    Impact force and braking distance grow with the square of speed: double the speed → 4 times the braking distance; triple it (20→60) → 9 times.

    Source: California Commercial Driver Handbook (DL 650) — §2.6.1 — Effect of speed on stopping distance

35 more Speed & Space Management questions are in the app, along with explanations and flashcards for every one.

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OnRoute is an independent study aid based on the federal CDL standards (49 CFR Part 383), the FMCSA Entry-Level Driver Training theory curriculum (49 CFR Part 380 Appendix A), and related Federal Motor Carrier Safety Regulations. It is not affiliated with, endorsed by, or sponsored by the FMCSA, AAMVA, or any state driver licensing agency. CDL knowledge tests are administered by your state, and state-specific requirements may vary — always consult your state's CDL manual.