2005 Model Commercial Driver’s License Manual When putting out the triangles, hold them between  yourself and the oncoming traffic for your own safety. (So other drivers can see you.) mph and the impact and braking distance are 16  times greater than at 20 mph. high speeds greatly  increase the severity of crashes and stopping  distances. By slowing down, you can reduce  braking distance. Use Your Horn When Needed.  your horn can let  others know you’re there. it can help to avoid a crash. Use your horn when needed. However, it can startle others and could be dangerous when used unnecessarily. Driving too fast is a major cause of fatal crashes.  You must adjust your speed depending on driving  conditions. These include traction, curves, visibility,  traffic and hills. perception Distance + reaction Distance + Braking Distance = Total Stopping Distance Perception distance.  The distance your vehicle travels, in ideal conditions; from the time your eyes  see a hazard until your brain recognizes it. Keep in mind certain mental and physical conditions can  affect your perception distance. it can be affected  greatly depending on visibility and the hazard itself.  The average perception time for an alert driver is 1¾ seconds. At 55 mph this accounts for 142 feet  traveled. The effect of Vehicle Weight on Stopping  Distance.  The heavier the vehicle, the more work  the brakes must do to stop it, and the more heat  they absorb. But the brakes, tires, springs, and  shock absorbers on heavy vehicles are designed to  work best when the vehicle is fully loaded. Empty  trucks require greater stopping distances because  an empty vehicle has less traction. 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. The average driver has a reaction time of ¾ second to 1 second. At 55 mph this accounts for 61 feet traveled. Braking distance. The distance your vehicle will  travel, in ideal conditions; while you are braking. At  55 mph on dry pavement with good brakes, it can  take about 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 a minimum of 419 feet. The faster you drive, the greater the impact or striking power of your vehicle. When you double  your speed from 20 to 40 mph the impact is 4 times  greater. The braking distance is also 4 times longer. Triple the speed from 20 to 60 mph and the  impact and braking distance is 9 times greater. At  60 mph, your stopping distance is greater than the  length of a football field. Increase the speed to 80  Slippery Surfaces.  It will take longer to stop, and it will be harder to turn without skidding, when the  road is slippery. Wet roads can double stopping  distance. you must drive slower to be able to stop in the same distance as on a dry road. reduce  speed by about one-third (e.g., slow from 55 to  about 35 mph) on a wet road. On packed snow,  reduce speed by a half, or more. If the surface is icy, reduce speed to a crawl and stop driving as  soon as you can safely do so. Identifying Slippery Surfaces. Sometimes it’s hard to know if the road is slippery. here are some  signs of slippery roads: you can’t steer or brake a vehicle unless you have  traction. Traction is friction between the tires and the road. There are some road conditions that  reduce traction and call for lower speeds. 2.6.2 – Matching Speed to the Road Surface The effect of Speed on Stopping Distance. 2.6 – Controlling Speed 2.6.1 – Stopping Distance Figure 2.11 Page 2-14 Section 2 – Driving Safely 