2.6.5 Speed and Traffic Flow

When you're driving in heavy traffic, the saf­est speed is the speed of other vehicles. Vehicles going the same direction at the same speed are not likely to run into one another. In many states, speed limits are lower for trucks and buses than for cars. It can vary as much as 15 mph. Use extra caution when you change lanes or pass on these roadways. Drive at the speed of the traffic, if you can without going at an illegal or unsafe speed. Keep a safe following distance.

The main reason drivers exceed speed limits  your speed for adverse weather or road condi­tions is to save time. But, anyone trying to drive faster than the speed of traffic will not be able to save much time. The risks involved are not worth it. If you go faster than the speed of other traffic, you'll have to keep passing other vehicles. This increases the chance of a crash, and it is more tiring. Fatigue increases the chance of a crash. Going with the flow of traffic is safer and easier.

2.6.6 Speed on Downgrades

Your vehicle's speed will increase on downgrades because of gravity. Your most important objective is to select and maintain a speed that is not too fast for the:

  • Total weight of the vehicle and cargo.
  • Length of the grade.
  • Steepness of the grade.
  • Road conditions.
  • Weather.

If a speed limit is posted, or there is a sign in­dicating "Maximum Safe Speed," never exceed the speed shown. Also, look for and heed warning signs indicating the length and steepness of the grade. You must use the braking effect of the engine as the principal way of controlling your speed on downgrades. The braking effect of the engine is greatest when it is near the governed rpms and the transmission is in the lower gears. Save your brakes so you will be able to slow or stop as required by road and traffic conditions. Shift your transmission to a low gear before starting down the grade and use the proper braking techniques. Please read carefully the section on going down long, steep downgrades safely in "Mountain Driving." 

2.6.7 Roadway Work Zones

Speeding traffic is the number one cause of injury and death in roadway work zones. Observe the posted speed limits at all times when approaching and driving through a work zone. Watch your speedometer, and don't allow your speed to creep up as you drive through long sections of road construction. Decrease your speed even further when a worker is close to the roadway.

Test Your Knowledge - Subsections 2.4, 2.5 and 2.6

  • How far ahead does the manual say you should look?
  • What are two main things to look for ahead?
  • What's your most important way to see the sides and rear of your vehicle?
  • What does "communicating" mean in safe driving?
  • Where should your reflectors be placed when stopped on a divided highway?
  • What three things add up to total stopping distance?
  • If you go twice as fast, will your stopping distance increase by two or four times?
  • Empty trucks have the best braking. True or False?
  • What is hydroplaning?
  • What is "black ice"?

These questions may be on the test. If you can't answer them all, re-read subsections 2.4, 2.5, and 2.6.