Page 112 - McWane Poles Sales Manual 2024

112
McWane Poles, A Division of McWane Inc.
TECHNICAL NOTES
Vehicle Impact
Vehicle impacts provide a dynamic loading to the pole. This dynamic loading is different than slow
(quasistatic) force application.
All energy is created by the vehicle and energy will be absorbed by vehicle in the form of crushing or the
pole bending or fracturing.
Force = Mass x Acceleration (Newton’s Second Law)
Acceleration = Velocity1 – Velocity2 / Time
Force = Mass x (∆Velocity / Time)
Example: Direct Car Impact on C3 30’ pole – Moment Capacity ~ 44,000 ft-lbs
Car Weight = 4,200 lb. or 1,905 kg
Speed = 40 mph or 17.88 mps
Time to Stop = .2 seconds
Bumper Height = 21 in or 1.75 ft
Force = 1,905 kg x 17.88 mps / .2 sec. = 174,330 N = 38,291 lbs
Moment Capacity Required to Stop Car= 38,291 lbs x 1.5 ft = 67,010 ft-lbs
The force on the pole is affected by the car crumble speed or the amount of time it takes for the car to get
to speed zero.