Hawaii CDL — General Knowledge practice
Hawaii CDL — General Knowledge: Speed & Space Management practice test
Choosing a safe speed, keeping a space cushion, adjusting for weather and traffic, and understanding stopping distance.
Content reviewed against official driver handbooks · August 12, 2026
12 questions · pass with 10 correct. You get instant feedback and an explanation after every answer.
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12 sample Speed & Space Management questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
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1. Why can railroad tracks be a 'space below' problem, according to the manual?
Correct answer: Trailers with low underneath clearance can get hung up partway across
The space under a vehicle can be very small, especially when it is heavily loaded. The manual singles out railroad tracks as a problem for trailers with low clearance underneath and warns against risking getting stuck halfway over.
Source: Hawaii Commercial Driver License Manual — Section 2.7.5, Space Below
2. With low beams you can see about 250 feet ahead, but the manual's minimum total stopping distance at 55 mph is 419 feet. What follows from that at night?
Correct answer: At 55 mph on low beams you could not stop within the distance you can see, so you must slow down
You have to keep your stopping distance inside your sight distance, which means driving slowly enough to stop within reach of your headlights. The manual's instruction for low beams is simply to slow down.
Source: Hawaii Commercial Driver License Manual — Section 2.11.4, Vehicle Factors
3. The one-second-per-10-feet following rule is given for normal conditions. What does the manual add for a slippery road?
Correct answer: The gap has to be much larger, because stopping takes far more room
After explaining how to count your following distance, the manual reminds you that a slippery road takes far more room to stop on, so the usual count is not enough.
Source: Hawaii Commercial Driver License Manual — Section 2.7.1, Space Ahead
4. A bus takes a banked curve too fast. What does the manual say can happen, depending on traction?
Correct answer: It can roll over if the tires grip, or slide off the curve if they do not
A banked curve is built for a particular safe 'design speed,' and a posted speed that suits cars may be too high for many buses. Taken too fast, a bus with good grip may roll over, and one with poor grip may slide off the curve.
Source: Hawaii Commercial Driver License Manual — Section 4.3.4, Speed on Curves
5. According to the manual, how do impact and braking distance at 80 mph compare with those at 20 mph?
Correct answer: They are 16 times greater
Doubling speed from 20 to 40 mph makes impact and braking distance four times greater, and tripling it to 60 mph makes them nine times greater. At 80 mph they are 16 times what they were at 20 mph.
Source: Hawaii Commercial Driver License Manual — Section 2.6.1, Stopping Distance
6. On a long, steep downgrade, how slowly does the manual say you must go?
Correct answer: At a speed low enough that the brakes can restrain the vehicle without overheating
In mountain driving your speed has to be low enough for the brakes to hold the vehicle back without overheating. Brakes that get too hot start to fade, and you have to push harder and harder for the same stopping power.
Source: Hawaii Commercial Driver License Manual — Section 2.16, Mountain Driving
7. On slippery winter roads, what does the manual say about stops you can see coming?
Correct answer: Anticipate them early and slow down gradually
The winter driving advice is to keep a longer following distance, watch far enough ahead to hold a steady speed, and work at spotting stops early so you can slow down gradually.
Source: Hawaii Commercial Driver License Manual — Section 2.13.2, Driving
8. At 55 mph in ideal conditions, about how far does a vehicle travel between the moment the driver's eyes see a hazard and the moment the brakes are applied?
Correct answer: About 203 feet
Perception distance at 55 mph is about 142 feet and reaction distance about 61 feet, so roughly 203 feet go by before braking even starts. Braking then adds about 216 feet, for a total of 419 feet.
Source: Hawaii Commercial Driver License Manual — Section 2.6.1, Stopping Distance
9. Once you are on the expressway during the road test, which three things are you expected to maintain?
Correct answer: Proper lane position, vehicle spacing, and vehicle speed
Before entering you check traffic, signal and merge smoothly. Once on the expressway, the test looks for proper lane positioning, proper spacing from other vehicles and proper speed, along with continued traffic checks in all directions.
Source: Hawaii Commercial Driver License Manual — Section 13.1.5, Expressway or Rural/Limited Access Highway
10. If you are not looking the recommended 12 to 15 seconds ahead, what does the manual say you may be forced to do?
Correct answer: Stop too quickly or make sudden lane changes
A large vehicle needs a lot of room to stop or change lanes. A driver who does not look far enough ahead may end up braking too suddenly or making abrupt lane changes.
Source: Hawaii Commercial Driver License Manual — Section 2.4.1, Seeing Ahead
11. You are driving a 60-foot rig at 50 mph in good conditions. By the manual's rule, how many seconds of following distance do you need?
Correct answer: 7 seconds
The rule is one second for every 10 feet of vehicle length, plus one more second at speeds over 40 mph. Sixty feet calls for 6 seconds, and at 50 mph the extra second makes 7.
Source: Hawaii Commercial Driver License Manual — Section 2.7.1, Space Ahead
12. You usually take a stretch of dry highway at 45 mph. Today the road is wet. Using the manual's rule of thumb, about what speed should you drop to?
Correct answer: About 30 mph
On a wet road the manual says to cut speed by about one-third; its own example is slowing from 55 to about 35 mph. One-third off 45 mph is about 30 mph.
Source: Hawaii Commercial Driver License Manual — Section 2.6.2, Matching Speed to the Road Surface
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