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From: hippo on 21 Jul 2010 17:37
Athol wrote:
>
> Mr.T <MrT(a)home> wrote:
>
> > Since the number of fatal accidents has increased in most states in recent
> > years despite big improvements in speed detection and vehicle safety, you
> > could certainly argue that their approach is not working.
>
> Given that the overall average safety of the vehicle fleet is improving
> every year, even breaking even on fatalities indicates that the approach
> to enforcement is not working. Going backwards indicates that the
> current enforcement approach is more than compensating for improvements
> in vehicle safety...
>

I heard a spokesman yesterday in justifying the rollout of the covert
camera vehicles, state that the NSW road toll had increased by 'a
horrendous amount' last year, with around 100 more people killed. 'The
fact that this year's road toll is back around par proves that the
Government's approach is already working.' Hmmm....

--
Posted at www.usenet.com.au
From: hippo on 21 Jul 2010 17:50
Sylvia Else wrote:
>
> On 18/07/2010 12:05 AM, hippo wrote:
> > Sylvia Else wrote:
> >>
> >>
> >
<http://www.rta.nsw.gov.au/roadsafety/speedandspeedcameras/speedingresearch.html>
> >>
> >> This page illustrates the sleight of hand frequently engaged in the the
> >> RTA and the Government.
> >>
> >> "Research has shown that the risk of a crash causing death or injury
> >> increases rapidly, even with small increases above an appropriately set
> >> speed limit."
> >>
> >> Yes, apparently, the research does show that. But note the expression
> >> "appropriately set".
> >>
> >> Skip down the page a bit, and we see
> >>
> >> "Based on this research it can be concluded that
> >> In a 60 km/h speed limit area, the risk of involvement in a
> >> casualty crash doubles with each 5 km/h increase in travelling speed
> >> above 60 km/h."
> >>
> >> Whoa there! How did we lose "appropriately set"? The cited research,
> >> which can be found at<http://casr.adelaide.edu.au/speed/>, makes it
> >> clear that the figures relate to a road where the mean free speed is
> >> about 60km/h. The road happens also to have a speed limit of 60km/h, but
> >> the result clearly depends on the mean free speed, not the speed limit.
> >> The paragraph above should say
> >>
> >> "Based on this research it can be concluded that
> >> On a road with a mean free speed of 60 km/h, the risk of
> >> involvement in a casualty crash doubles with each 5 km/h increase in
> >> travelling speed above 60 km/h."
> >>
> >> We all know of roads where pretty much everyone exceeds the limit
> >> because it's absurdly low. The mean free speed on such roads
> >> significantly exceeds the speed limit.
> >>
> >> Sylvia
> >>
> >>
> >
> > ..and nobody ever sems to continue to the bits in various research papers
> > which pont out that individual drivers travelling significantly *below*
> > the prevailing speed for that area may also face increased risk of
> > involvement in accidents.
> >
>
> The cited research questions whether that effect is real - vehicles amy
> be travelling slowly for reasons that put them at higher risk of being
> in an accident.
>
> But I'm concerned about the analysis that purports to show a reduction
> in fatalities and/or injuries given a reduction in speed. The approach
> appears to be to assume that the vehicles involved in a particular
> accident would have been in the same relative positions at the start of
> the accident sequence, with the lower speeds then resulting in either
> reduced impact speeds, or no impact at all. No allowance is made for
> drivers making the same basic mistakes, but with the vehicles being
> closer when the accident sequence starts. The latter seems entirely
> likely with accidents where a vehicle turns across the path of another.
>
> But the RTA isn't really interested in what the research shows. When I
> pointed out a fundamental flaw in the analysis that purported to show
> that speed cameras reduced fatal accidents[*], the RTA's response was
> that similar research overseas had produced similar results (probably by
> the same flawed reasoning).
>
> [*] Essentially, they took places where there had been fatal accidents,
> typically only one or two, and put speed cameras there. Then they said
> "Look, no accidents in the following years". Yet you'd get the same
> result if you just identified such places, and did nothing other than
> look at the next couple of years - the point being that a small number
> of fatalities at a place is just a random event, and the fact that an
> accident occurs tells you nothing about what's likely to happen in future.
>
> You could then conclude that doing nothing reduced fatal accidents.
>
> Sylvia.
>
>

You'd not be too far short of the mark in a way!

I *wish* I could remember the source, or that I'd kept a copy at the time
(we're probably talking late in Greiner's tenure as Premier, or shortly
afterwards).

There was a reasonably comprehensive study looking at the efects of
traffic lights, roundabouts and other traffic management measures at
intersections with long term accident histories.

Two reasonable predictable findings were:
1/ introducing traffic lights generally lowers the number of collisions
and injuries almost immediately;
2/ introducing roundabouts, especially mini ones, often *increases* the
number of collisions, but the speeds tend to be much lower injuries and
fatalities are reduced.

BUT - at nearly every intersection surveyed, the accident rate started to
climb after about a year or two, until it was usually back around its
original level after seven years.

One of their conclusions was that doing virtually *anything* will probably
deliver a benefit, because the change in conditions makes drivers
concentrate more, but that the benefit will nearly always be temporary.

--
Posted at www.usenet.com.au
From: Sylvia Else on 21 Jul 2010 21:49
On 22/07/2010 7:37 AM, hippo wrote:
> Athol wrote:
>>
>> Mr.T<MrT(a)home> wrote:
>>
>>> Since the number of fatal accidents has increased in most states in recent
>>> years despite big improvements in speed detection and vehicle safety, you
>>> could certainly argue that their approach is not working.
>>
>> Given that the overall average safety of the vehicle fleet is improving
>> every year, even breaking even on fatalities indicates that the approach
>> to enforcement is not working. Going backwards indicates that the
>> current enforcement approach is more than compensating for improvements
>> in vehicle safety...
>>
>
> I heard a spokesman yesterday in justifying the rollout of the covert
> camera vehicles, state that the NSW road toll had increased by 'a
> horrendous amount' last year, with around 100 more people killed. 'The
> fact that this year's road toll is back around par proves that the
> Government's approach is already working.' Hmmm....
>

It never seems to occur to the government that the steps they've put in
place may be the cause of the increased road toll. The atttitude is
always that if the road toll rises, then we need more of the same.

Sylvia.
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