Safety First 11: Speed Management

Safety First · Lesson 11 of 30 · Safe Operating Procedures
Free safety education based on the federal Entry-Level Driver Training (ELDT) theory curriculum. This is not certified ELDT training and does not count toward a CDL.

The eleventh unit of the federal Class A theory curriculum is Speed Management. It covers how to choose a safe speed for the road, the weather, and the traffic, and how to keep a safe following distance.

What this unit covers

Under 49 CFR Part 380, Appendix A, this unit teaches driver-trainees to manage speed effectively in response to various road, weather, and traffic conditions. It also covers methods for calibrating safe following distances, taking into account commercial motor vehicle braking distances under different conditions, including traffic, weather, and the vehicle's weight and length.

1. Stopping distance

CDL manuals describe total stopping distance as the sum of three parts:

  • Perception distance: the distance the vehicle travels from the time your eyes see a hazard until your brain recognizes it. CDL manuals give an average perception time of 1¾ seconds for an alert driver, about 142 feet at 55 mph.
  • Reaction distance: the distance the vehicle continues to travel, in ideal conditions, before you physically hit the brakes, in response to a hazard seen ahead. The average reaction time is ¾ second to 1 second, about 61 feet at 55 mph.
  • Braking distance: the distance it takes to stop once the brakes are applied. At 55 mph on dry pavement with good brakes, it can take about 216 feet.

At 55 mph, the total stopping distance is a minimum of 419 feet.

Speed changes everything. CDL manuals explain that when you double your speed, the vehicle hits with four times the impact, and the braking distance is also four times longer. Tripling speed, for example from 20 to 60 mph, makes the impact and braking distance nine times greater.

Weight matters too. A heavier vehicle needs more work from the brakes to stop and makes the brakes absorb more heat. CDL manuals also note that empty trucks need greater stopping distances, because an empty vehicle has less traction.

2. Matching speed to the road surface

  • Wet road: reduce speed by about one-third, for example from 55 mph to about 35 mph.
  • Packed snow: reduce speed by half or more.
  • Ice: reduce speed to a crawl, and stop driving as soon as you can safely do so.
  • Hydroplaning: it can happen at speeds as low as 30 mph if there is a lot of water. To regain control, release the accelerator and push in the clutch. Do not use the brakes.

3. Speed and curves

Slow down to a safe speed before you enter a curve. Braking in a curve makes it easier to lock the wheels and skid. Tests have shown that trucks with a high center of gravity can roll over at the posted speed limit for a curve. Never exceed the posted speed limit for the curve.

4. Speed and distance ahead

You should always be able to stop within the distance you can see ahead. At night, low beams let you see a shorter distance, so slow down when you use them.

5. Following distance

CDL manuals give this rule: you need at least one second for each 10 feet of vehicle length at speeds below 40 mph. Above 40 mph, add one second.

  • A 40-foot vehicle: 4 seconds below 40 mph, 5 seconds above.
  • A 60-foot vehicle: 6 seconds below 40 mph, 7 seconds above.

How to measure it: wait until the vehicle ahead passes a clear landmark, such as a shadow on the road or a pavement marking. Count the seconds until your vehicle reaches the same spot, and compare your count with the rule. When the road is slippery, you need much more space to stop.

Quick check

  1. What are the three parts of total stopping distance? (Answer: perception distance, reaction distance, and braking distance.)
  2. On a wet road, by about how much should you reduce your speed? (Answer: by about one-third.)
  3. Using the CDL manual rule, what following distance does a 60-foot vehicle need above 40 mph? (Answer: at least 7 seconds.)

Find every Safety First lesson under DRIVE.

This lesson is general education, not legal advice. Follow your state CDL manual and your training provider, and confirm current rules with FMCSA. Drivers getting their first Class A or Class B CDL, upgrading from Class B to Class A, or getting a hazardous materials, passenger, or school bus endorsement for the first time must, with limited exceptions, complete entry-level driver training from a provider listed on FMCSA's Training Provider Registry.

Sources

FLY YOUR WHEELS!

Comments

Post a Comment

Popular posts from this blog

Safety First 01: Orientation

Safety First · Lesson 01 of 30 · Basic Operation Free safety education based on the federal Entry-Level Driver Training (ELDT) theory curriculum. This is not certified ELDT training and does not count toward a CDL. The federal Class A theory curriculum lists Orientation as its first unit. It is the first of 30 theory units in the federal Class A curriculum for a commercial driver's license (CDL). This unit covers the rules and responsibilities that come with the job, and the consequences of breaking those rules. Prefer to listen? Hear this lesson on the 18whings Safety podcast. What this unit covers Under federal regulation ( 49 CFR Part 380, Appendix A ), the Orientation unit introduces the training curriculum and the parts of a combination vehicle, and then covers: Basic safety principles and regulations for commercial vehicles, including an overview of the Federal Motor Carrier Safety Regulations (FMCSRs) and the Hazardous Materials Regulations (HMRs). Resp...
Read more

Safety First 03: Pre- and Post-Trip Inspections

Safety First · Lesson 03 of 30 · Basic Operation Free safety education based on the federal Entry-Level Driver Training (ELDT) theory curriculum. This is not certified ELDT training and does not count toward a CDL. The third unit of the federal Class A theory curriculum is Pre- and Post-Trip Inspections . It covers how a driver checks the vehicle before driving, during the trip, and at the end of the day's work. Federal rules place inspection duties on the driver and on the motor carrier. This lesson explains the driver's part. Prefer to listen? Hear this lesson on the 18whings Safety podcast. What this unit covers Under 49 CFR Part 380, Appendix A , this unit teaches driver-trainees to conduct pre-trip and post-trip inspections, including appropriate inspection locations, and en route inspections. The unit refers to two federal rules: 49 CFR 392.7 and 49 CFR 396.11 . 1. Before driving: the driver must be satisfied Under 49 CFR 392.7(a), a driver may not driv...
Read more

Before You Buy Your First Truck: Gross Revenue vs. Real Owner-Operator Income

Stage: OWN  |  Last reviewed: September 17, 2026 "I grossed $5,000 this week!" You'll hear numbers like that around truck stops and on social media. Those numbers are real, but gross revenue is not income. Before you leave a company-driver job to buy your first truck, you need to understand the difference between what a truck brings in and what the owner takes home . Gross revenue vs. take-home pay As a company driver, your paycheck is (mostly) your income. The company pays for the truck, fuel, insurance, repairs, permits, and empty miles. As an owner-operator, you pay for all of that. Your gross revenue has to cover every cost of running a truck before you get paid, and before taxes, health insurance, retirement, and time off. What does it cost to run a truck? ATRI's Operational Costs of Trucking report is one of the most-cited benchmarks. Its 2026 update (covering 2025 data) found the average marginal cost of operating a truck reached a record $2.336 pe...
Read more