40 mph (65kph)
Imagine that you are riding your snowmobile on the trail at night. Up ahead, a tree has fallen down across the trail. As you ride, the headlights on your snowmobile illuminate 200 feet (61 meters) in front of you. Therefore, you will not see the fallen tree until it is 200 feet (61 meters) in front of your snowmobile.

A normal reaction time is 1.5 seconds. If you are traveling at 40 mph (65 kph), it will take you 1.5 seconds, or traveling 88 feet (27 meters), before you apply the brake to stop.

At 40 mph (65 kph), you need about another 70 feet (21 meters) to stop your snowmobile. With the normal reaction time of 88 feet (27 meters) and 70 feet (21 meters) to stop while going 40 mph (65 kph), that is 158 feet (48 meters) total you will travel before stopping.

With snowmobile headlights that illuminate 200 feet (61 meters) ahead and 158 feet (48 meters) required for stopping time, you should be able to stop 42 feet (13 meters) from the fallen tree, a very safe distance unless the trail is icy, which will require a longer stopping distance.

At 40 mph (65 kph) or below, you are normally not over riding your headlights.

50 mph (80 kph)
In the experience of law enforcement officers, many riders operate their snowmobiles between 30 and 45 mph (50 and 70 kph) at night. Between 45 and 50 mph (70 and 80 kph), snowmobiles can start over riding their headlights.

At 50 mph (80 kph) you would travel about 110 feet (33.5 meters) before you started to apply the brake. You would then be 90 feet (27 meters) from the tree. Since you would need at least 80 feet (24 meters) to stop the machine or make an appropriate move, traveling at 50 mph (80 kph) is dangerous.

65 mph (105 kph)
Speeds of more than 50 mph (80 kph) at night are extremely dangerous. At 65 mph (105 kph), you would have already traveled 143 feet (43.5 meters) by the time you ever start to apply the brake. You would still need about 100 feet (30.5 meters) to stop, but would be only about 57 feet (17 meters) from the tree by then. At this speed, it would be almost impossible to stop in time to avoid the fallen tree.

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