Failure to Control Speed
Driving too fast is a major cause of fatal crashes. To effectively control speed, the truck driver must continually determine the Total Stopping Distance and adjust speed accordingly. Total Stopping Distance is the sum of Perception Distance, Reaction Distance, and Braking Distance.
Total Stopping Distance = Perception Distance + Reaction Distance + Braking Distance
- Perception Distance means the distance the vehicle travels, in ideal conditions, from the time the driver’s eyes see a hazard until the driver’s brain recognizes it. The average perception time for an alert driver is 1.75 seconds. At 55 mph, this accounts for 142 feet traveled.
- Reaction Distance means the distance the vehicle travels, in ideal conditions, before the driver physically hits the breaks. The average driver has a reaction time of .75 to 1 second. At 55 mph this accounts for 61 feet traveled.
- Braking Distance means the distance the vehicle will travel, in ideal conditions, while braking. At 55 mph on dry pavement with good brakes, it can take about 216 feet to come to a stop.
Total Stopping Distance Calculation
The total stopping time for a vehicle traveling 55 mph is a minimum of 419 feet. The foregoing Total Stopping Distance increases depending on: vehicle speed, vehicle weight, traction, curves, visibility, traffic, and hills. That is, the presence of these factors should cause the truck driver to lengthen his or her calculated Total Stopping Distance and reduce speed.
- Vehicle Speed: Speed exponentially impacts total stopping distance. When a truck driver doubles his or her speed from 20 to 40 mph, the impact on Total Stopping Time is four times greater.
- Vehicle Weight: The heavier the vehicle, the more work the brakes must do to stop it; however, the common truck’s mechanics are designed to work best when the vehicle is fully loaded. As such, empty trucks require greater stopping distances because an empty vehicle has less traction.
- Traction: Slippery surfaces require lower speeds. Wet roads can double stopping distance. As such, truck drivers must reduce speed by about one-third on wet roads. On packed snow, truck drives must reduce speed by half or more. If the surface is icy, a truck driver must reduce speed to a crawl and stop driving as soon as can safely be done. Other signs of slippery roads included: shaded areas in icy conditions, bridges, melting ice, black ice, vehicle icing, just after the rain begins, and hydroplaning.
- Curves: Curves increase the risk of lost traction or roll-over.
- Visibility: A truck driver must always be able to stop his or her vehicle within the distance that he or she can see. Fog, rain, and like conditions require reduced speeds. At night, a truck driver cannot see as far with low beams as with high beams; consequently, the truck driver must slow down when switching from high beams to low beams.
- Traffic: When driving in heavy traffic, the safest speed is the speed of other vehicles.
- Hills: Total Braking Distance on a downgrade increases.
You should consult with an attorney regarding failure to control speed or your specific situation. We have successfully prosecuted numerous lawsuits against negligent trucking companies.
Written by:
Mark Fassold
Watts Guerra LLP
4 Dominion Drive, Bldg 3, Suite 100
San Antonio, Texas 78257
Phone (210) 447-0500
© Watts Guerra LLP 2015
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