Exploding the Myths around Low Level Speeding Ian Johnston July
2013
Slide 2
Kinetic Energy is the immediate cause of injury - managing
energy exchange is the principal goal (thank God for Newton!)
Slide 3
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)
Slide 4
Speed and Safety A huge research literature has this rule of
thumb bottom line (has survived in the toughest school of all peer
review) A 5% decrease in average speed leads to approximately a 10%
decrease in all injury crashes and a 20% decrease in fatal
crashes
Slide 5
1999 & 2000 2003 & 2004 Total 435307 Vulnerable road
users 175106 Vehicle occupants 260201 Deaths in Melbourne
Slide 6
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?
Slide 7
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?
Slide 8
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 cant get them to slow down!
Why not?
Slide 9
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
Slide 10
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
