Debunking the myths of “low level” speeding

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Angela RaczOnline Training CoordinatorKnowledge Transfer - ARRB Group

P: +61 3 9881 1694E: training@arrb.com.au

Technical support

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Jerome CarslakeNRSPP ManagerARRB Group

Ph: +61 3 9881 1670jerome.carslake@arrb.com.au

Moderator:

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Housekeeping

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Webinar is = 35 mins

Question time = 15 mins

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GoToWebinar functions

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Please type your questions here

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Professor Ian Johnson AMChair of the NRSPP

E: irj111@bigpond.net.au

Today’s presenter

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Debunking the Myths around Low Level Speeding

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The direct cause of physical injury is kinetic energy

so managing energy exchange is the principal goal in injury prevention (thank God for Newton!)

E=½m(v²)

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Everyone accepts that impact speed is directly related to injury severity

Many dispute that speed has any influence on crash risk (kinetic energy remains potential if no crash occurs)

What are the facts?

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Case/Control Method: Adelaide Study

• 2 times risk at 65 in a 60 zone

• 30 times risk at 80 in a 60 zone

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Empirical Method – Speed Limit Changes

• USA interstate highways

• Hume Highway in Victoria

• 50 km/h limits in Melbourne

• Rune Elvik’s “meta-analysis”

A 5% decrease in average speed leads to approximately a 10% decrease in all injury crashes and a 20% decrease in fatal crashes

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Correlational Method

UK study of rural roads of differing engineering standards

• Within each standard, the roads with the highest average travel speeds, had the highest casualty crash frequencies

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If the science is so clear, why is speed moderation so controversial?

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1. Traditional speed limit setting and enforcement tolerances• 85th percentile speed limits

• Posted limits vs implied limits

2. Vehicle design and advertising

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100

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Everyday experience

Exceed speed limit by small amounts nearly every day and nothing bad happens

This is where our dilemma comes into sharp focus

Image source: http://media.bloxi.com/media/uploads/images/4083cb82-16ff-4527-ab5a-2673275ceb72.jpg 16

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Preventive Medicine

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?

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Magnitude of problem = risk x frequency

• “High Range” speeding offences (>15 km/h over limit)• relatively rare

• high or extreme risk

“dramatic” safety problem

• “Low Range” speeding offences (<15 km/h over limit)• very common

• elevated risk

very significant safety problem

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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?

Image source: http://resources2.news.com.au/images/2011/01/01/1225980/109890-booze-bus.jpg

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Preventive Medicine

When a small individual risk is widespread, we must change behaviour of the population

No problem when the cost seems small

• Seat belt wearing

• Motorcycle helmet wearing

• Bicycle helmet wearing (but early teen males?)

Image source: http://riderswestmag.com/images/uploads/biker630.jpg

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We fight 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

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What are our tools? (1)

Roads

• local area traffic mgt.

• intersection design

• roadside management

• speed limits

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The Goal – To Match Speed and Infrastructure

Urban

80 km/h or lower

Rural

100 km/h or higher

high standard / high

volume roads

low standard / low

volume roads

Moderate

speed

enforcement

Some lower

speed limits

Crashworthy

infrastructure

Some lower

speed limits

Intense

speed

enforcement

50 km/h60/ 70/

80 km/h

Lower speed

limits

Crashworthy

infrastructure

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What are our tools? (2)

Vehicles

• reduced speed performance• “intelligent speed adaptation”

systems• more appropriate instrumentation• different marketing

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What are our tools? (3)

Enforcement

• “automated”o fixed camera

o mobile cameras (overt, covert)

• intensity

• tolerances

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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

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Questions?

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