Transcript Please choose one of the following slides as your title

Insert the title
of your
Monitoring
national
casualty
presentation
here
trends
in Great
Britain
Presented
by Name Here
Jeremy
Broughton
JobNovember
Title - Date
16
2009
Contents
1
Background
2
Casualty forecasts for 2010
3
Monitoring casualty trends
4
GB Casualties in 2008
5
Car Secondary Safety
Page  2
Background
 In the late-1990s the British Government began to prepare for
the next road accident casualty reduction target, the target year
would be 2010
 The context for the target was provided by forecasts of the
number of casualties in 2010
- The forecasts needed to take account of the effects of national policy
where it could be established reliably
- They should also take account of the changing volume of road travel
 The presentation will describe how the forecasts were prepared
 Progress towards the target has been monitored annually, which
has allowed the reliability of the forecasts to be checked
 The implications of the 2008 data for the forecasting procedure
will be examined.
Page  3
Approach to casualty forecasting
 The approach is based on
analyses of past casualty
rates per billion veh-km of
traffic
ln(KSI per billion veh-km)
6.0
5.5
 Previous research (in GB
and other countries) had
found that national casualty
rates declined exponentially
5.0
4.5
4.0
1978
Page  4
1983
1988
1993
1998
 This model had provided
useful forecasts, but
needed to be improved to
take account of road safety
policy
Casualty forecasts
 Most road safety measures affect different groups
differently so the forecasts are disaggregate, with five road
user groups:
- car occupants
- motorcyclists
- pedestrians
- pedal cyclists
- others (mainly people travelling by bus, coach, van or lorry)
 The casualty rates are adjusted to take account of the
DESS measures:
- Reducing Drink/Driving
- Road safety Engineering
- Improved Secondary Safety (crashworthiness) of cars
 The adjusted rates estimate what would have happened
without the DESS measures.
Page  5
Idealised illustration of the forecasting model
Adjusted rate, 1983-98, showing
what might have happened
without the DESS measures
)
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s
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a
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a
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What might happen in 1999-2010
with the Core program but no
further DESS measures
AActual rate
Baseline forecast
Assumed
effect of
new
policies
B
Final forecast
Fi
1980
Page  6
1985
1990
1995
2000
2005
2010
2015
An actual forecast
 This example is for car
occupants KSI (Killed or
Seriously Injured)
- The red line is fitted to the
adjusted rates from 1983 to
1998
log(KSI rate)
4.8
- This is extrapolated to 2010
to forecast the rate
4.5
- The forecast rate is
multiplied by the volume of
car traffic forecast for 2010
to estimate the number of
casualties
4.2
3.9
1983
Page  7
1988
1993
1998
2003
2008
- The traffic volume comes
from a ‘transport scenario’
The outcome
 The actual rates have been
added to the previous slide
for car occupants KSI
- The outcome matched the
forecast for the first four
years
log(KSI rate)
4.8
- From 2003 the rate has
fallen below the forecast,
indicating that new policies
have taken effect
4.5
4.2
3.9
1983
1988
1993
1998
2003
- These falls are independent
of the benefits of improved
secondary safety of modern
cars (considered later)
 Different patterns are found
with the other road user
groups
Page  8
Transport scenarios
 There is uncertainty about traffic growth, so a range of
‘transport scenarios’ was defined, based on official (DfT)
forecasts for 2010
 Each scenario consisted of a growth prediction for each of
the 5 road user groups
 Implausible combinations were excluded (e.g. car use and
walking would both grow strongly)
 This left 36 scenarios, and a set of forecasts (KSI, slight
casualties) was prepared for each
Page  9
New measures
 These include innovatory measures that might be taken,
also substantial expansion of existing measures
 The ‘Safety Targets and Accident Reduction’ Group was
set up to consider the new measures that might be
included in the future road safety strategy
 The outcome was a list of 9 possible new measures, and
the potential effectiveness of each was assessed using
available evidence
 The casualty forecasts depend upon which of these
measures are assumed to be implemented
 A review in 2007 concluded that by 2010 about 75% of
the predicted benefit would have been achieved
Page  10
Final forecasts for 2010
 KSI and slight casualty
forecasts were prepared
for each of the 36
transport scenarios
 Each pair of forecasts is
plotted as a point on
this figure (100%=no
change from 1994-98
baseline)
 Attention focussed on
the more plausible
scenarios
Page  11
Fatality forecasting
 Trends for Killed and KSI
had been very similar
until 1998, so no
specific target was
adopted for Killed
100=1994-98 average
140
120
 The trends have since
diverged, so attention
has focused on
forecasting fatalities
100
80
Killed
KSI
 The same approach had
proved successful
60
1990
Page  12
1995
2000
2005
Fatality forecasting: 2007 and 2008 data
100=1994-98 average
140
 The number Killed fell
by 7% in 2007 and by
14% in 2008
120
 These sudden changes
call into question the
approach to casualty
forecasting
100
80
Killed
KSI
1995
2000
 Some preliminary
results will be presented
60
1990
Page  13
2005
The casualty trends for pedestrians did not change
Pedestrians
4.2
1.7
3.7
1.2
3.2
0.7
2.7
Killed
Serious
0.2
1983 1987 1991 1995 1999 2003 2007
Page  14
2.2
Log(serious rate)
Log(fatality rate)
2.2
 There is no sign of a trend
change for pedestrians in
2007 or 2008, so the
pedestrian casualty
forecasts are not affected.
 The same is true of pedal
cyclists and of motorcyclists.
…but the fatality trend for car occupants did
5.0
Car occupants
3.0
4.5
2.5
4.0
2.0
3.5
Killed
Serious
1.5
1983
Page  15
3.0
1987
1991
1995
1999
2003
2007
Log(serious rate)
Log(fatality rate)
3.5
 The trend for serious car
occupant casualties was
unchanged in 2008, so the
forecast is not affected
 The trend for fatal car occupant
casualties fell sharply in 2008,
following the precedent of the
previous recession in 1990
 The same is true of "Others”,
the great majority of whom
travel by bus, coach, van or
lorry.
 Why are the responses of the
fatal and serious trends
different?
Improved Secondary Safety of cars
 Secondary safety (crashworthiness) refers to the protection
offered by a vehicle involved in an accident, whereas primary
safety refers to systems such as steering and brakes which
should help to avoid accidents.
 Changes in secondary safety can be assessed by studying the
proportion of injured car drivers who are Killed or Seriously
Injured
 Cars are grouped by their ‘year of first registration’. In any
one year of accidents, drivers of newer cars tend to be less
seriously injured
 A statistical model is used to identify the effect
Page  16
Some results
Killed, NBU
0.2
0.0
pre-1976 1980-81 1986-87 1992-93 1998-99 2004-05
log(relative severity proportion)
-0.2
-0.4
-0.6
model_2
-0.8
-1.0
-1.2
-1.4
Page  17
model_1
 Separate analyses are made for
Killed and seriously Injured on
Built-Up (urban) and Non BuiltUp (rural) roads
 In each case, results show that
secondary safety began to
improve about the 1990 model
year, and progress since then
has been steady
 Future benefits can be
estimated, conditional upon an
assumption about how much
longer this progress will
continue
Summary results
Reduction in the proportion of
casualties who were killed or
seriously injured
Seriously
Killed
injured
Urban
roads
67%
42%
Rural
roads
59%
43%
 These detailed results can
be summarised by
comparing cars first
registered in 2006-07 with
those first registered in
1990-91
 About 2/3 fewer injured
drivers of the more
modern cars were killed ,
and about 2/5 fewer were
seriously injured
 A problem for the future:
how to assess the benefits
of advanced primary safety
features such as Electronic
Stability Control?
Page  18
Thank you
Presented by Jeremy Broughton
16 November 2009
Tel: 01344 770879
Email: [email protected]
Page  19