Perception Distance
- The distance your vehicle travels, in ideal conditions; from the time your eyes see a hazard until your brain recognizes it.
- Average perception time is 1 ¾ seconds
Reaction Distance
- The distance you will continue to travel, in ideal conditions; before you physically hit the brakes, in response to a hazard seen ahead.
- Average reaction time is ¾- 1 second.
Braking Distance
- The distance your vehicle will travel, in ideal conditions; while you are braking.
- At 55 mph on dry pavement, it can take 216 feet.
Total Stopping Distance
- The total minimum distance your vehicle has traveled, in ideal conditions; with everything considered, including perception distance, reaction distance and braking distance, until you can bring your vehicle to a complete stop.
- At 55 mph, your vehicle will travel 419 feet.
- Perception Distance + Reaction Distance + Braking Distance = Total Stopping Distance
- The faster you drive, the greater the impact of your vehicle to stopping.
- The heavier your vehicle, the more work the brakes must do to stop it.
- Account for the road surface and its impact on your speed:
- Slippery surfaces take longer to stop and it will be hard to turn without skidding.
- Wet roads can double stopping distance.
- Reduce speed by about one-third on a wet road.
- On snow, reduce speed by half.
- On ice, reduce speed to a crawl.
- Slippery surfaces:
- Shaded areas may remain icy after other areas have melted.
- Bridges can freeze before the road will freeze.
- Melting ice can make it more slippery as the water lays on top of ice.
- Black ice is a thin layer of ice that is clear enough to see the road beneath it.
- Rain is most slippery just after it begins as it mixes with the oil on the road.
- Hydroplaning occurs when a vehicle hits water or slush and the tires lose their contact with the road and have little to no traction.
- You can regain control by release the accelerator and pushing in the clutch.
- Do not use brakes to slow down.
- Can occur as low as 30 mph
- More likely if tire pressure is low or tread is worn
- Can also happen on standing water
Curves
- Adjust your speed for curves on the road.
- If you take curves too fast:
- You can lose traction and skid off the road.
- You can keep traction and the vehicle can roll over.
- Slow to a safe speed before you enter the curve.
- Try not to brake, instead, start the curve slow and accelerate as you go through a curve.
Distance ahead
- Be able to stop within the distance you can see.
- Be aware of the impact of fog, rain and darkness.
Downgrades
- Speed will increase on downgrades because of gravity.
- Do not exceed “Maximum Safe Speed.”
- Use the braking effect of the engine to control your speed.
- Shift to low gear and save your brakes to slow down or stop.
Work Zones
- Observe the posted speed limits.
- Decrease even further when worker is close to a roadway.
Traffic Flow
- In traffic maintain speed with other vehicles.
- Use caution when changing lanes or passing.
- Pay attention to traffic speed as well as posted road speeds.
- Driving faster to save time will not be safer.