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Exploding the Myths around Low Level Speeding. Ian Johnston July 2013. Kinetic Energy is the immediate cause of injury - managing energy exchange is the principal goal (thank God for Newton!). Maximum Impact Speeds. Car/pedestrian 30 km/h Car/motorcyclist 30 km/h
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Exploding the Myths around Low Level Speeding Ian Johnston July 2013
Kinetic Energy is the immediate cause of injury- managing energy exchange is the principal goal(thank God for Newton!)
Maximum Impact Speeds • Car/pedestrian 30 km/h • Car/motorcyclist 30 km/h • Car/tree or pole 40 km/h • Car/car (side-impact) 50 km/h • Car/car (head-on) 70 km/h Source: Tingvall & Howarth (1999); Wramborg (2005)
Speed and Safety A huge research literature has this “rule of thumb” bottom line A 5% decrease in average speed leads to approximately a 10% decrease in all injury crashes and a 20% decrease in fatal crashes (has survived in the toughest school of all – peer review)
Preventive Medicine (1) Does everyone who: • smokes get lung cancer? • is obese get heart disease? • exceeds the speed limit crash? and the reverse • is everyone who gets lung cancer a smoker?
The Health Prevention Paradox • Rose: “.. (the) irony of preventive medicine is that many people must take precautions to prevent illness in only a few.” • Why is .05 our BAC limit? • Why Random Breath Testing?
Preventive Medicine (2) When a small individual risk is widespread we must change behaviour of the population So folk wear belts and helmets and accept RBT but we can’t get them to slow down! Why not?
We fight like hell when there is assumed to be a personal cost • Low level speeding the classic example • Assumed to cost time, to be frustrating, etc – all go against the increasing pace of life • After years and years of enforcement tolerances speed limits have lost the concept of limit
Not Rocket Science! • Research is clear • Higher speed = greater crash risk and more severe crashes • Preventive Medicine principles are clear • Must change population behaviour • Tackle all obstacles (social change) • Intense enforcement but with powerful supporting education