Calculating a Safe Speed

Stopping a snowmobile is trickier than stopping a wheeled vehicle on a street or trail. To ensure that you can stop safely in any situation, you must be able to calculate a safe speed based on stopping distances.

• Maintaining a safe speed allows you to control your machine and stop in time to avoid a collision.
• The greater the speed, the greater the stopping distance.
• To determine a safe speed, you must know stopping distances and how to factor in sight distance and reaction time.

Sight Distance

Sight distance is the distance from which you can see and identify a hazard, not necessarily the total distance you can see. You often see an object before you’re able to identify it as a hazard. If the stopping distance to an object is greater than the sight distance, you’re in danger of hitting the object.

Reaction Time

Reacting to a sudden need to stop involves these steps:

• Seeing something
• Recognizing it’s a hazard
• Deciding what to do
• Braking or steering around the object

Reaction Time Distance

Reaction time distance is the distance the snowmobile travels during the time it takes you to react.

• The distance depends on the reaction time (in seconds) and speed (in feet per second) and is calculated as:
  Reaction Time Distance = Reaction Time × Speed.
• Accidents occur in just a few seconds, so think of your speed in feet per second (multiply mph by 1.46667).
  • 15 mph = 22 feet per second
  • 30 mph = 44 feet per second
  • 45 mph = 66 feet per second
  • 60 mph = 88 feet per second
• At 30 mph with a reaction time of three seconds, the reaction time distance is 132 feet (3 sec. x 44 ft./sec.).