The following are some articles on traffic accidents published in our previous Newsletters.
Road Deaths in London Rise, Published November 2007
The London Road Safety Unit (part of TfL) has recently published the road accident figures for 2006 (see www.tfl.gov.uk/corporate/2840.aspx for the full report). Fatal accidents rose by 8% over the previous year to 231, and serious injuries also rose by 8% to 3,715. These figures were unexpected of course and TfL suggest there is some error in “data processing” but have been unable to identify exactly what. Although slight injuries fell by 8%, those figures are more suspect due to possible variations in reporting. The KSI data is particularly disappointing bearing in mind that resources tend to concentrated on reducing the killed and seriously injured numbers. The result is that the target for a reduction of fatalities of 50% by 2010 looks unlikely to be met as you can see from the chart taken from the TfL report following:
The truly amazing thing that this graph shows is that in essence fatalities in London have barely changed since 1994 despite the enormous growth in expenditure on road safety – particularly on speed humps, speed cameras, 20 mph zones, speed limit reductions, and lots of other similar “gestures”. Meanwhile traffic volumes in London have not changed much in those years. KSI figures show a more positive trend over the same period, but even there the latest data shows a major rise since the low point seen in early 2005.
Taking the overall casualty figures, pedal cyclists were the only group though that showed an increase, probably simply because cycling is more common. Accidents involving powered two-wheelers, which have been a growing problem in recent years, seem at least to have stabilised.
(Editor: it appears to me that these figures demonstrate that road safety policies need to be substantially rethought. The same problems are of course reflected on a national basis where fatalities are also not falling significantly. Clearly the current policies are not working but all we get from Government ministers and road safety advocates tends to be “more of the same will solve the problem”. There is currently an enormous amount of your taxpayers’ money being wasted on ineffective solutions to reducing road deaths.)
Road Deaths Rise But Casualties Fall, Published August 2004
Figures have recently been published for road traffic accidents for the UK in 2003. Numbers killed were 3,508 which is actually 77 higher than the previous year. Government targets for accident reduction are measured with reference to the average over the years 1994-1998. In those years, there were 3,578 deaths on average, which shows that no progress has been made at all.
Transport Policies and Speed Cameras
The above was immediately jumped on by commentators such as the Association of British Drivers (ABD - see http://www.abd.org.uk) who claimed it was clear evidence that existing road safety policies such as more speed cameras and road humps were deeply misconceived. For example, Transport Minister Alistair Darling claimed in the week before the above data was published that speed cameras erected in the last three years had saved 100 lives. “So why isn’t this reflected in the figures?” asked the ABD. The ABD also pointed out that Britain now has one of the worst records for reducing road deaths in the EU. For example, when comparing road deaths in 2002 with the average of 1994-1998, deaths have been reduced by 12.6% in France, 22.9% in Germany, and 35.5% in Portugal.
Alistair Darling’s claims were based on a detailed analysis of road camera sites, based on before/after accident data. However this approach has lots of potential flaws. Often changes in traffic flows are not measured, reversion to mean effects ignored and other road safety engineering measures implemented at the same time not taken into account.
Injuries Fall However
But the good news is that overall casualties were down 3 per cent. Seriously injured fell by 6% to 33,707, and slightly injured fell by 4% to 253,393. There was a particularly good reduction in child injuries which fell by 8%. The breakdown by type of road user is as follows:
Incidentally any of our readers who are still awake will notice that the total does not appear to add up, but that is how the data was published by the Department for Transport. See the full report at: http://www.dft.gov.uk/stellent/groups/dft_transstats/documents/page/dft_transstats_029323.hcsp
(Editor’s Comments: It is disconcerting that injury accidents continue to fall, but deaths do not. In reality, it may simply be that the injury data is unreliable as there is known to be gross under-reporting of such figures, whereas fatalities are rarely missed. It could be that much of the apparent saving is due to fewer minor accidents being reported as it is very suspicious that road deaths seem to not be statistically linked to overall accidents. Of course one of the possible distortions in the figures is that the police are responsible for collecting and reporting the accident data, when they also share responsibility for road safety - a structure that almost guarantees some bias in the data, particularly bearing in mind their current workload and lack of resources.
But irrespective of the above comment, it is plain that fatalities to motorcycle riders continue to rise, which is another disconcerting trend. These were up 14% on the previous year, and up 48% from the baseline. Pedestrian accidents and child accidents appear to be continuing to fall, but is this because we are walking less and children are now often taken to school by car? In summary, interpreting this data to draw conclusions about the effectiveness of road safety programmes is exceedingly difficult. But it is also true that if you argue that fining several million motorists every year for breaking a technical speed limit is having a positive impact on overall road deaths, then clearly you would be wrong.).
London & Bromley Data
The London Road Safety Unit also recently published data for London which shows similar overall trends. For example, fatalities fell by 7 to 272 in 2003, but are actually still up by 9% on the 1994-98 baseline. Serious injuries in London fell by 9% last year which is a good result and may be because of a stronger concentration of effort on prevention of such accidents. Overall casualties were down by 7% on 2002.
The data for Bromley is shown below, which is generally very positive. Bromley was second in the list of all London boroughs in the overall reduction in accidents, even though Bromley adopted a “no more speed humps” policy in 2002! Surely a demonstration that Bromley’s policies are wiser than other London boroughs? Or is this the result of bias in data collection by the police as many people in Bromley are coming to realise that reporting minor incidents to the police is a waste of time as often they simply do not respond?
Fatalities in Bromley rose to 13 (but the small numbers are affected by statistical randomness and therefore difficult to interpret). It’s worth pointing out before everyone is too self congratulatory about the above numbers that the weather was significantly drier than normal in 2003. This would have had a positive impact on accident numbers.
Congestion Charge Impact
There was no significant difference in overall injuries in the central London boroughs as against outer London boroughs (minus 6.3% versus minus 7%), although the City of London at minus 23% did particularly well. It is difficult to draw any firm conclusions on the impact of reduced traffic in the Congestion Charging zone.
Why Accidents Don’t Fall, Published February 2004
It is puzzling to many people, that despite the massive expenditure on speed humps, speed cameras and other traffic calming measures in the last few years, accident numbers do not fall as expected.
As shown in a previous Newsletter, road traffic fatalities in London actually rose by 20% between 1995 and 2002, and slight injuries only show a slight fall. This is despite the fact that many millions of pounds have been spent on road safety schemes in London in that period (expenditure is running at over £20 million per year in London at present).
It’s also worth bearing in mind also that every single scheme has also been judged to show a very substantial return on investment, using calculations promoted by ROSPA and other bodies. These are based on reported historic before and after accident rates from the Molasses database maintained by local authorities. Robert Gifford of PACTS recently claimed that Local Authorities can save one life by spending £100,000 on such measures, but clearly they do not in reality.
Why do the expected accident reductions disappear when wide area accident figures are examined?
An interesting light was thrown on this in a study published in 1999 by the US Federal Highway Administration called “Research, Development and Implementation of Pedestrian Safety Facilities in the UK”. This said:
“Pedestrian accidents have declined sharply over the past 5 years. However, establishing causes and effects is not easy. As noted earlier, the amount of pedestrian activity had also declined sharply.
In addition, the evaluation of the accident reduction effects from specific countermeasures has rarely been rigorous, partly because of practical difficulties. The typical method consists of a comparison of reported accidents (or casualties) for 3 years before and after the scheme. It rarely includes the known confounding factors such as changes in traffic flow, changes in traffic composition (particularly pedestrian flows), background trends in accident numbers, regression to mean effects, adaptive behaviour by vulnerable road users or more controversial aspects such as accident migration.
Elvik (1997), reviewing United Kingdom and other accident studies, found that very few allowed for these factors.
He also found that when they were taken into account, little or no accident reduction benefit could be directly attributed to the countermeasure.
To compound the problem of evaluation, no work appears to have been done to show how the (claimed) accident savings from particular schemes or programs relate to the overall changes in accident numbers.”
The last two paragraphs have been highlighted because they are the key points. They show that the accident benefits are often a mirage.
As a simple example of this, the ROSPA figures for the expected benefit of a road hump scheme is a reduction in accidents of 68%. However this does not take into account the actual traffic diversion which we know from other studies can be very high. In addition it ignores the other effects mentioned above, and the data is based on subjective reports by the same council staff who devised the schemes in the first place. This is not science, it’s not even magic, it’s just slight of hand.
Pedestrian Accident Trends - The Truth
Pedestrian accidents particularly demonstrate the fallacy of many road accident claims as this is one of the few areas where accidents are going down. The number of pedestrian fatalities in the UK was at a peak of 3,153 in 1966, and declined thereafter. Each year since 1990 has seen a new record low for pedestrian fatalities - in 2002 it was 775. Total pedestrian casualties have also declined substantially.
But when pedestrian activity rates are examined, there has in fact been a similar decline (see chart above for trends in travel modes). From 1985/86 (the earliest data known) to 2002 the distance walked fell by 21%. There has been a particularly marked decline in walking by children, one of the pedestrian groups with the highest casualty rate (even more so after dark due to security concerns). In fact, according to a DETR report in 1997, they suggested that real accident rates for that group might actually be increasing!
These pedestrians have often switched to using car transport, which as we reported in Issue 22, is safer per mile travelled, if not as healthy otherwise.
So when you next hear a politician or local authority staff member claiming success for reducing child accidents by traffic calming measures, take it with a pinch of salt.
Accidental Deaths in London. Published February 2004
Some interesting statistics were disclosed by the London Ambulance Service in their recent review of traffic calming. Apparently there are 7,500 accidental deaths a year in London, of which about 2,000 are from external causes and 5,500 from medical incidents (eg. heart attacks). However within the first 2,000 are about 300 deaths from road accidents but there are of course numerous other reasons such as falls, fires, poisonings and drowning that make up the other 1,700 (Editor: Yes it’s a dangerous world).
To put it bluntly, you are much more likely to die from other accidental causes than from a road traffic accident. This data hardly supports the contention that road deaths are extraordinarily excessive as some people have alleged, or that they can necessarily be easily reduced, as they are clearly as rare as other accidents. Obviously the weight of expenditure and effort put into reducing road accidents has to be balanced against the effort put into reducing other causes of premature death.
London Accident Trends & Targets, Published December 2003
In March 2000, the government published it’s targets for road casualty accident reduction for the next ten years. By 2010 the targets were to reduce the killed and seriously injured (KSI) by 40% and a 10% reduction in slight injuries. In addition the KSI figure for children was aimed to be reduced by 50%. These targets were to be compared against a base line of the average figures for 1994-1998.
Transport for London (TfL) have recently produced a report on how London is performing against these targets. For London overall the data is as follows:
The trend for killed and seriously injured (KSI) is best illustrated by the following chart from the report:
The above seems to show that London is likely to meet the target set for 2010. However if you look at the fatal accidents, the trend is nowhere near as positive:
Particular attention was paid in the Mayor of London’s Road Safety Strategy to reducing the injuries to pedestrians, pedal cyclists, powered two wheelers (motorcyclists) and children. The numbers for those categories in respect of KSIs are as follows:
The glaring anomaly here is clearly the figure for motorcyclists where the accident rate has gone up considerably. Although usage of such vehicles has increased over the last 10 years, particularly in central London, the increase in accidents is much higher than could be accounted for by that cause.
How does Bromley compare to other London boroughs? Well the following chart shows the KSI trend for Bromley:
Although it’s difficult to draw any firm conclusions from the above, partly because of the random fluctuations in the data, it would clearly be wrong to assume that Bromley is on it’s way to meeting the target. Note also that in fact Bromley Council have raised the target even further by entering into a “Public Service Agreement” to achieve a 50% reduction.
Bromley has the same problem as the rest of London in that motorcycle accidents are rising rapidly (KSIs up by 26%). However pedal cyclists KSIs have halved, possibly because of a fall in usage.
Reasons for Higher Motorcyclist Deaths
It is interesting to speculate on the reasons for the rise in motorcycle accidents because extensive effort has been put into this area in the last few years in terms of better training of riders and tougher regulations. For example, Bromley plans to tackle this problem by further education of teenagers on the dangers of scooter riding.
Increase in “Street Furniture” a Problem?
One possible cause has been the increase in “street furniture” such as pedestrian refuges, bollards and signposts. Minor accidents often end up as fatal when a motorcyclist hits one of these items, as in the recent death in Perry Street reported in issue 23. At the recent inquest into this matter, the mother of Benjamin Hopkins who died, called on the council to redesign central refuges to make them less dangerous. She said “Ben didn’t stand a change as the island was huge and made of concrete and steel”.
(Editor’s Comments: I think this is certainly worth studying some more as it appears that the saving in pedestrian injuries is currently being offset to a large extent by the increase in motorcyclists injuries, which are often fatal).
The data above is based on figures to the end of the year 2002. The data for the first half of 2003 has just been released and shows an overall decrease in London of 6% in accidents in comparison with the previous year, but a rise in fatalities. Bromley casualties were down 18%.
Cutting Excessive Speed and Warning of Road Hazards, Published June2003
Much emphasis has recently been placed on reducing vehicle speeds on British roads. So for example, over 3 million speeding tickets are likely to be issued this year, and speed humps have been sprouting everywhere. And yet these expensive programmes have had negligible effect on road accident statistics. All that has happened is that an army of people (police, court staff, and the manufacturers and installers of speed cameras and road humps) have been deployed to achieve very little.
At present we have a regime where minor infringements of speed limits result in severe punishment, as if we were all naughty children who needed severe disciplining. In the case of speed humps, we are actually chastised with corporal punishment, when it has long been abandoned in our courts and schools.
However, it is still recognised that reducing vehicle speeds at known danger spots (such as on Leesons Hill in Orpington) would clearly be advantageous. How to achieve changes in driver habits, or warn drivers of temporary oversights, at an economical cost and without unnecessarily criminalising large swathes of the population is the issue. Perhaps education is a better approach?
Well recently the Transport Research Laboratory (TRL) have reported on the use of electronic warning signs. These can warn drivers of excessive speed, or alternatively be used to indicate that dangerous bends or junctions are coming up. You may have seen some already in Bromley and more extensive use is anticipated. Examples are shown below.
The picture above shows a sign that lights up to display a vehicles speed when it is above a certain level (yes the van was actually doing 38 mph on Leesons Hill, before braking).
The picture above (on Main Road, Biggin Hill) shows a sign warning of an impending dangerous bend (it lights up if the driver is approaching too fast).
Now the really interesting thing about this report is that it conclusively shows that these devices are not just effective at slowing down drivers, but that they are also much better than speed cameras at reducing accidents. At the sites studied, where these devices have been installed over a number of years, average speeds were reduced by 4 mph, and by 7 mph for junction and bend warnings. Accidents were reduced by one third!
Another major advantage was that the effects did not seem to wear off over time, and the initial installation cost and running costs are a fraction of those for speed cameras. These devices can also be used as a good alternative to speed humps on minor roads. The full report can be seen on the internet at http://www.trl.co.uk/static/dtlr/pdfs/TRL548.pdf
(Editors Comments: Clearly a major improvement over the use of speed cameras and road humps with much greater acceptability to the general public. Bromley council staff are to be congratulated on pioneering these devices in the London area.)
What Does a Road Accident Cost? Published February 2003
When new road safety schemes are being considered, the projected savings are usually calculated. Most such schemes show a very quick “payback” period, at least when being designed! But how are the costs of the accidents that are saved actually worked out? Well the government publishes a regular report called the “Highways Economics Note No.1” which attempts to answer that question (available from the Department of Transport if you want to see the full details).
A Recent Accident in Sundridge Ave, Chislehurst
Research in the early 1990s was used to determine both the direct costs (medical treatment costs, lost output due to absence from work, associated police and insurers costs and damage to property) and indirect costs. The latter, the “human” cost is somewhat of a subjective item as it is worked out on a “willingness to pay” basis. It represents the “pain, grief and suffering to the casualty, relatives and friends in the case of injuries” for example.
The values calculated in the year 2000 were as follows as an “average per accident”:
Note that a serious injury is defined in the UK by an overnight hospital stay, a slight injury is simply any accident involving an injury however trivial (such accidents should legally be reported to the police whereas non injury accidents don’t need to be). For all injuries therefore, the average total cost per accident is £52,070 of which 71% is the “human” cost and the rest are more direct costs.
There are different figures for urban, rural or motorway road accidents (the latter tend to cost more), so for Bromley roads the likely cost is £63,000 per accident, after including a cost estimate for non-injury accidents which are not in the figures shown above. However one has to be exceedingly careful when using the average figures. For example, take the recently proposed road safety scheme for Elmstead Lane in Chislehurst. This road had an average of about 6 slight injury accidents per year in the last few years (there were no serious or fatal accidents). The proposals might save one accident per year at a cost of about £50,000 (for the speed bumps or alternative treatments as proposed). If you took the average cost of all injury accidents as £63,000 then it looks a “no-brainer” as the payback is less than one year. However, if the only accidents saved are “slight” ones, as is quite likely in this case, then the benefit is £15,000 for an expenditure of £50,000 which doesn’t look nearly as good.
If you actually study the accidents that took place in Elmstead Lane, it also seems very difficult to justify an average cost of £15,000 each - many of them were very trivial. One explanation for the discrepancy is that most of the benefit is supposedly the intangible “human” cost, and the direct benefit is actually only £3000 for an expenditure of £50,000! In reality the extra “willingness to pay” cost of £12,000 for a slight accident probably grossly overestimates what people would actually do if given the choice between spending the money on that or other things - their “willingness to pay” may be a pollsters mirage.
Of course that is not to argue that such expenditure is unreasonable, but the difficulty is that it may be more sensible to spend that amount on other road safety measures, or other social services such as improving the NHS, where a better “payback” may be achieved.
One point that clearly comes out from the above figures is that the cost of a fatal accident is many times more than that of a serious accident which is itself much more costly than a slight accident. Therefore road safety remedial measures that concentrate on fatal or serious accidents are clearly the most cost effective.
However where there are clusters of slight accidents then this can be symptomatic that more serious accidents will occur (such as in Dunkery Road, Mottingham). On the other hand a wide spread of minor accidents as on the rest of the Mottingham Estate, does not necessarily indicate that more serious accidents will occur (and they haven’t in this case) so it was difficult to justify the wide area road hump scheme on that estate on a cost/benefit basis.
The use of “willingness to pay” to evaluate accident costs does provide a good way of comparing the relative costs of slight or serious injuries, but it distorts the cost justification versus other expenditure. For example it is rarely taken into account when evaluating the cost of major road improvement schemes or other social expenditure such as NHS facilities. In these cases, even when the justification is clear and there is a clear “willingness to pay” by the electorate, the government typically says they can’t afford the cost, or that there are other priorities. You can possibly see why UK roads are some of the safest in the world, but we spend more time in traffic jams than almost anyone else, and have one of the worst health systems in the developed world.
Bromley Accident Statistics, published April 2002
Provisional data for the 2001 year show that road accident casualties decreased by 10% to 1145, including a fall in the number killed or seriously injured by 55% to 86. The decrease in overall casualties is probably statistically significant, although you have to bear in mind that accident figures tend to relate to weather conditions and we have had a run of relatively mild winters.. However there was a 5% increase in accidents involving motorcyclists, probably due to their increased numbers. Targets for accident reduction agreed with the government have been further reduced.
Note that based on the final data for the year 2000, Bromley has a generally low number of casualties compared with other London boroughs based on the accident rate per head of population.. As you might expect though, it is worse than average for accidents to motorcyclists and car users (cars are the predominant means of transport in Bromley which is different in central London boroughs).
Hawthorne Experiments, published November 2001
Recent copies of this Newsletter have given you some accident statistics that demonstrate that the major emphasis on traffic calming schemes and speed reduction measures (e.g. hundreds of extra speed cameras, lots more speed bumps), seem to have negligible impact on overall accident statistics, which stubbornly refuse to come down. This despite the fact that there are studies that clearly appear to demonstrate the effectiveness of these measures based on before/after studies of accident statistics in particular locations. There are three major reasons why these statistics are misleading:
Firstly because they often ignore the effect of diverting traffic. To be accurate you need to take account of the changed volume and mix of traffic which is rarely done.
Secondly they often fall into the common traps of using selective statistics (ie. the bad comparables are ignored and the good ones published), or they don’t allow for extraneous factors such as weather conditions, or they ignore random statistical variation. Rarely are “confidence levels” attached to the numbers as they then make poor political headlines (in fact the statistics are usually based on such poor experimental design that it would be folly to do so anyway).
Thirdly though they totally ignore the major problem when experimenting on human beings, that predictions tend to be self fulfilling. This was clearly demonstrated back in about 1930 in a series of research projects in industrial psychology undertaken by Elton Mayo and known as the Hawthorne Experiments (there are several references on the Internet to this work if you want more details as it is a classical study in this field). One of the things he did was to test the effect of increasing or decreasing lighting conditions in the workplace. With an increase, he expected an improvement in output, and got it. With a decrease, he was expecting a reduction, but got an increase. In other words, any change improved performance. Why was this? Because the subjects expected the change to improve performance because they knew that was what the experiments were about, and hence it did. Behaviour changed to match peoples expectations.
So let’s take up the analogy with the introduction of speed cameras. People expect the installation of speed cameras will reduce the number of accidents (after all we are told they are only sited at accident black spots), so in fact they might well react accordingly, ie. they will act to match their expectations. How long will this effect last: well quite a long time according to Mayo, but clearly it could not last for ever because otherwise you could simply keep changing the environment and endlessly improve performance.
One of the clear conclusions is that when experimenting on people you have to be very careful when interpreting the results. This is why medical experiments typically use a double-blind technique where neither the subject not the collector of the statistics knows who is getting the real medicine or who is getting the dummy.
To really produce proper before/after studies to measure the effectiveness of accident prevention measures, you therefore have to be exceedingly careful. Certainly it must be extended over a long period of time so the Hawthorne effect wears off. Secondly, you should also try removing the change to see what effect that has, or introduce other similar but different measures to see whether any change in the environment stimulates the same change. For example, compare the effect of a real speed camera, with a sign warning of hazards ahead. Also you need to separate the collectors of the statistics from the interpreters (in practice they are the same police at present). Unfortunately it is so difficult to do this kind of study in an unbiased and effective manner that in practice it is unlikely ever to be done properly.
Final Comment: Take any claims for breakthroughs in traffic accident reduction with a pinch of salt.
The Dangers of Drink, published November 2001
An interesting recent article in the Daily Telegraph covered the dangers of drinking and walking. Last year, 793 adult pedestrians were killed on the roads. However, the latest available statistics show that almost half had been drinking and a third were over the legal limit for driving. In fact, from other statistics, it is clear that the vast majority of road accidents to pedestrians happen not from vehicles running off the road, but from pedestrians recklessly stepping into the road.
Clearly measures to separate pedestrians from road traffic are very important, and simple measures such as barriers to control where pedestrians can cross, could be effective. But take care over Xmas!.
London Accident Statistics, published August 2001
For comparison, the following graphs are taken from the Mayors Transport Strategy document discussed more fully in a later article.
Graph 1 - London Casualties Killed
The lines in the above chart, from the top, represent numbers of pedestrians, motor vehicle users, motorcyclists and cyclists.
Graph 2 London Casualties Seriously Injured
The lines in the above chart, from the top, represent numbers of motor vehicle users, pedestrians, motorcyclists and cyclists. Note the large number of pedestrians killed in comparison with other road users. Also note the relatively static situation over the last few years in London as a whole, which again tends to suggest that either Bromley is doing something different or is suffering from a statistical aberration or fluke.
UK Accident Statistics, published August 2001
For comparison, here are some details of the accident statistics for the whole of the UK for the year 2000.
There were 320,283 road casualties in Great Britain, with 3,409 killed (this is only 14 fewer than 1999 and only 12 fewer than in 1998). Road accidents involving injury were down only 1% overall. Child casualties fell by 6%, which reflects the situation in Bromley, but motor bike casualties rose by 8% even though the volume of such traffic fell.
As usual, the UK accident statistics seem to be remarkably insensitive to political action measures such as heavy central government funding of traffic calming schemes, speed reduction campaigns, increased criminalisation of the general public for traffic offences and the like. It would appear to your editor that some changes to the strategy should be considered.
For example, the Department of Transport (DTLR) has just committed a further £30 million in support of traffic calming schemes by local councils, despite the recent evidence of increased traffic pollution from road humps.
Of course, one of the interesting questions is why did Bromley accident statistics improve so much more than the UK as a whole? Is Bromley's traffic engineering approach better than other local councils, or has traffic become so much more congested in Bromley that slower traffic has resulted in fewer accidents and injuries?
If any of our readers have an explanation for this perhaps they could let us know. There was a change of policy a couple of years ago in Bromley, to concentrate on accident black spots rather than area traffic calming schemes, possibly prompted by pressure from BBRAG, but it would seem rather early for that to have had much effect.
Bromley Accident Statistics, published August 2001
Here are some more details of the accident statistics for Bromley in the calendar year 2000 that were mentioned in our last newsletter. Note that these are collected by police and will only include those accidents reported to them, which is primarily those involving personal injury.
Deaths fell from 14 to 8, with no children being involved. However, you should bear in mind that deaths are a very small proportion of all accident injuries and tend to be "extreme" events that are not statistically significant because of the low numbers.
In the case of adults, serious injuries fell from 115 to 75 and slight injuries from 1161 to 1138. For children, serious injuries fell from 21 to 9, and slight injuries from 146 to 81. Breaking down the figures by the type of road user gives the following data for casualties:
The above graph shows that in essence there was a steady downward trend until 1991 (a lot of which can be attributed to the M25 taking through traffic of Bromley roads). In fact the injury numbers actually rose in the last two years even though traffic volumes fell. In the period from 1991-1997, when “traffic calming” schemes of the typical multiple speed bump type were widely introduced in Bromley, the accident statistics show that there was no overall benefit in traffic accident reduction.
Why is this? Probably because most of these schemes simply cause traffic to divert (and in some cases to less safe alternative roads). Our conclusion is this: that the money wasted on such schemes would have been much better spent on actually tackling the worse locations, and the causes of such accidents.
More evidence to support this view can be obtained by looking at the locations of personal injury accidents in the borough. The council report contains a list of the worse 115 locations from the years 1995 to 1997. Neither Blackbrook Lane in Bickley, nor Watts Lane/Manor Park Road in Chislehurst appear in those statistics.