A new bridge over the Thames in East London would only benefit ‘former Tory MPs’, a Newham councillor has claimed.
Councillor Airdrie Dalden is objecting to plans from Transport for London which include a bridge between the borough and the Royal Borough of Greenwich on the south of the river.
Quoting the example of journalist Matthew Parris, councillor Dalden said: “The vast majority of people currently crossing the Thames here are former Tory MPs in swimming trunks. Women of any ethnic group who wish to wear modest clothing, and I count myself in that category, are not going to put on a swimming costume and cross the Thames. Swimming is a discriminatory form of transport.”
Parris was criticised by the Port of London Authority in 2010 after writing about his experience of being swept a mile upriver when swimming across the busy commercial waterway at night.
Mayor Boris Johnson claims that the new Thames Gateway Bridge across the river would link the transport poor Thamesmead estate and Woolwich development area in Greenwich with residential and redevelopment areas around Beckton and the Royal Docks in Newham, creating opportunities for one of Britain’s most deprived boroughs.
But Councillor Dalden told AWWTM that the money Johnson proposes spending on the bridge would not “benefit every aspect of Newham, which is an ethnically diverse borough.”
“You look around and of the people who are crossing the Thames here, they do not belong to wider ethnic groups. The majority of swimmers are former Tory MPs like Matthew Parris and Boris Johnson. Fact.”
Transport for London are now considering a compromise solution which will involve building half a bridge.
So TfL have produced a short advert once again asking everybody to calm down, play nice, and share the road. I figured it might make a good excuse to post again this thing that I scribbled a couple of years ago.
On the Guardian Bike Blog, Tom Richards points out that “while we’d all love better cycling infrastructure, there is neither the money nor the political will…” Therefore we should focus on easier and more populist things — like conquering human nature and legislating to re-educate 30 million people.
Now, leaving aside the fact that the effects of changing driver education (if there are ever any effects at all, and it’s not a very robustly researched field) have long lag times — as long as street lifecycles. And leaving aside the fact that there is no evidence that this sort of intervention would ever actually have any significant effect on the sort of issues we’re concerned about, such as occurrence and severity of motor vehicle/cycle crashes (but if Richards were to propose a randomised controlled trial…). And leaving aside the fact that it could have, at best, only a small effect on the arguably more important issue of barriers to cycling, which are more about subjective assessment of the comfort of the environment than about raw injury statistics, and so can make no significant contribution to solving the wider issues which cycling is tied to. Basically, leaving aside the fact that this is, at best, a mediocre proposal. The interesting question is, why do people keep clinging to these kinds of ideas?
The idea that somehow physical engineering is difficult and expensive and unpopular, while changing human behaviour is quick, easy, cheap and effective, is one that the British are remarkably strongly attached to. It is manifested in a wide variety of rarely very effective campaigns and initiatives, from marketing the unmarketable to the bizarrely widespread belief that obscure details of insurance law are a significant influence on behaviour. One of my favourite examples of the attitude was caught by Freewheeler a couple of years ago, from “3 feet please” campaigner and now ex LCC trustee David Love:
This provoked a response from David Love in the Comments, who among things writes:
Sure, segregation would be great but in London at least there’s no room and no money so it’s not going to happen.
Campaigning for behaviour change is more realistic right now
And there you have the ‘realism’ of a man who is LCC Trustee and Vice Chair.
But the British tradition of soft measures goes far wider, deeper and further back than this. Motorists may moan about having been the victim of a “war” that restricts their freedom, polices their movements, or sends campaigns of severe punishment for accidental and unavoidable infringement of petty rules, but the reality is that right from the start, when the red flag acts were repealed, this country’s response (and that of much of the English-speaking world) to the problems that motorists create on the road has largely been light touch and libertarian, in which the children are simply asked again and again to play nice, even as they become ever greater bullies, and only if they’re really bad might they have their pocket money docked. We encourage and raise awareness, appeal to the legendary British sense of fair play, and still believe that the ideal road is within reach if only we can persuade everybody to get along through courtesy, good manners, and communicating our intentions clearly to one another.
Joe Moran has an entertaining history of this English approach to road safety in the chapter “please don’t be rude on the road” in On Roads. Amongst others he tells the story of Mervyn O’Gorman, who argued against introducing a driving test because all that a motorist should require is a natural “road sense”, and who acted on his belief that the cause of road accidents is poor communication by inventing the Highway Code, a list of mostly legally baseless customs and courtesies, explaining that “is is just as ungentlemanly to be discourteous or to play the fool on the king’s highway as it would be for a man to push his wife off her chair at the Sunday tea table and grab two pieces of cake.” Perhaps most entertaining is his coverage of the period in the 1930s when “courtesy cops” went around with megaphones politely asking errant drivers to behave themselves. He concludes:
Underneath this appeal lay an uncomfortable truth: many members of the respectable middle classes were incompetent drivers who were to blame for fatal road accidents. Rather than turning them into criminals through putative legislation, British traffic law relied on appeals to their sense of fair play. It was always better, went the mantra of the time, to cultivate good habits than propose bad bills. [Sound familiar?] So the courtesy cops did not prosecute motorists; they offered friendly advice to the careless. The Times blamed accidents on what it called ‘motorious carbarians’ — the few bad apples hidden among the vast majority of gentlemanly drivers, who could be relied upon to break the law sensibly. Motoring correspondents railed against excessive regulation in the 1930s in a way that eerily echoes today’s campaigns against speed cameras and road humps. ‘Regulation after regulation pours from the Ministry of Transport in a never-ending flood,’ complained the Daily Mirror in 1934 … but ‘courtesy and good manners may be cultivated easily enough by everyone.’
They say that the definition of madness is doing the same thing over and over and expecting a different result. For eighty years or more the answer to motorists playing nice has been just a little bit more education and awareness raising, and look where it has got us. It’s time to call off the search for the British sense of fair play and abandon the naive idea that meaningful and worthwhile change on the road can be achieved with a few gentle nudges.
7 years, 4 months and 18 days ago, a train crashed in Cumbria. So it seemed like an appropriate moment to post this extract from another project that I’ve been working on. It’s all a draft so your comments and corrections on matters of style and fact are very much welcome.
Just before 8am on the 5th of October 1999, a commuter train left London Paddington bound for Bedwyn in Wiltshire. A few minutes later, just as it was getting into its stride through the inner suburbs, it approached the location where the bidirectional terminus station tracks cross over one another and organise themselves into strictly segregated “up” and “down” direction main lines in a great tangle of points. The train passed straight through a yellow warning signal without slowing, and soon after skipped the red stop signal that was all there was to protect those Ladbroke Grove crossovers ahead.
The morning InterCity from Cheltenham hit the commuter train head on at a closing speed of 130mph. The front car of the commuter train was crushed by the heavy express locomotive, which in turn shed its diesel across the tracks while its rake of coaches, full of momentum and still propelled by a second locomotive at the rear, jackknifed into the flaming wreckage. Thirty one people were killed on that occasion; more than 500 were injured.
The driver of the Bedwyn commuter train was obviously unavailable to explain why he failed to respond to the two signals warning him of the danger ahead. The front carriage of his train was completely destroyed in the impact; neither driver was available to defend against media speculation and blame. An Inquiry was ordered, and Lord Cullen was appointed to get to the bottom of the matter and find out what went wrong.
Cullen was unusually thorough in his investigations into what went wrong at Ladbroke Grove, eventually publishing not one but two reports. The first, as you would expect, looked at the immediate cause of the crash. It reconstructed the story of how the driver of the commuter train jumped the lights, but found that far from being one man’s mistake, a catalogue of errors had added up to the catastrophe. The driver had only graduated from his training two weeks before the crash, and the inquiry uncovered multiple problems with the train company’s training programme, including inadequate instruction in signal procedures. The train was equipped with an Automatic Warning System, with audible in-cab alarms to warn the driver when the train passes signals — but the system was too simple to differentiate between yellow warning signals and red stop signals, and each time the Bedwyn train passed a signal, the driver had pressed the acknowledgement button to prevent the system from automatically stopping the train, as was the correct practice for yellow signals. The signals themselves had been erected in confusing arrays on gantries over the tracks, with views restricted by nearby bridges and by the line’s newly installed overhead power supply. And the position and design of the signal lights meant that at 8am on a bright October morning, westbound train drivers would see the reflection of the sun “lighting up all the signals like Christmas trees”, as one driver told the inquiry, making it far from obvious that a signal was set to red rather than yellow. The inquiry concluded that a momentary lapse of concentration caused the driver to respond incorrectly to the first signal, while the poor visibility and reflections led him to incorrectly read the second.
The inquiry revealed that the crash on the fifth of October was just the visible tip of an iceberg. The failures that led to the Bedwyn train jumping the lights had led eight others to do exactly the same at that one signal in the previous six years, with a 67 red signals in total passed on the tracks out of Paddington during that time. So-called “signal passed at danger” events — SPADs — were endemic, and railway management had never taken the problem seriously enough. It was only by chance and good fortune on those previous occasions that there was no oncoming express train. In fact, it was later calculated that, at the rate that signal jumping was occurring at Ladbroke Grove, a catastrophic crash was absolutely inevitable in that location, and at an expected rate of one every 14 years.
In short, Ladbroke Grove revealed that there were widespread failings in the railway system that enabled mistakes to happen and to go uncorrected, and the risks resulting from these failings were accepted as an inevitable fact of life. Cullen realised that his inquiry into the one incident couldn’t ignore the much bigger problem on the railway. And he was proved right even before he could publish his conclusions. One year after the Ladbroke Grove crash, an InterCity bound for Leeds at 115mph derailed on poorly maintained track at Hatfield, killing 4 passengers and revealing the scale of the failings that would soon lead to the collapse of Railtrack, the privatised owners of the railway infrastructure.
Cullen knew that the failings on the railway were far too numerous to identify and fix in one report — he had identified a dozen serious problems in the Ladbroke Grove case alone — and besides, fixing problems would not guard against new ones creeping in. Instead, Cullen introduced the systems that would enable a continual process of identification and correction of problems, and a long-term plan for improvement. Key amongst these were the creation of the Rail Safety & Standards Board (RSSB) and the Rail Accident Investigation Branch (RAIB) to oversee an overhaul of the railway’s safety culture. RAIB, modelled on the older Air Accident and Marine Accident Investigation Branches, was created to ensure that an independent investigator got to the bottom of every incident on the railway, rooting out the failures at all levels of the industry. RAIB does for railway incidents today what Cullen did for Ladbroke Grove: the investigator makes extensive enquiries, consults the detailed operational records, and reconstructs events, leading to thick reports highlighting the lessons that are to be learned. Working practices get revised, enforcement of rules is tightened, and investment is made in new technology.
RAIB investigates incidents with the aim of preventing anything like them from ever happening again. But the one thing RAIB does not do is assign blame. It inherits from Cullen the recognition that in a complicated system like the railway, it takes more than one person to mess up. Malice and incompetence, laziness and greed, and momentary lapses of concentration are surely all characteristics that can be expected of people from time to time. But if those traits are ever allowed to lead to a catastrophe, it is the system that has failed at least as much as any individual.
As Cullen put it, describing the problem of the epidemic of jumped signals — SPADs — at Ladbroke Grove:
Underpinning my approach to these matters is the following. On the one hand the public quite rightly expects that there should be no SPADs which run the risk of causing injury. On the other hand human nature is fallible: no matter the training and experience — and they are extremely important — it is impossible to exclude the possibility of such an event. … if and to the extent that the safe operation of a train is dependent on one person it is essential that the demands which the railway system makes on him or her take adequate account of human factors.
This is a central principle of the systems that Cullen put in place. Ladbroke Grove was not the fault of one driver for failing to stop at a signal: the life and limb of 500 passengers should never have been placed entirely in the hands of one fallible human, just a single momentary lapse of concentration between him and disaster. So in Cullen’s system, the railway industry now identifies situations where one easy mistake could have terrible consequences, and it eliminates them.
Frequently, this means re-configuring track to reduce the kind of the movements that could allow a crash to happen, and introducing new technology to automatically protect trains from the minor mistakes that human drivers and signallers inevitably make. Cullen’s report, for example, specifically advised that Britain roll out technology called Automatic Train Protection (ATP). This system, coupled with other advances in modern signalling technology, makes it pretty much impossible to accidentally crash a train: the positions of all the trains on the line are automatically detected by circuits in the rails and the system keeps them apart by lengths of several train braking distances, refusing to allow the person operating the signals to put trains on collision courses; and the trains are sent information about speed limits and signal states, preventing their drivers from speeding and, even if the driver fails to do so, stopping automatically at red lights. ATP had been investigated by British Rail before privatisation, but the government at the time was not prepared to pick up the billion pound bill for installing it across the network. Once the inevitable had happened at Ladbroke Grove, it was perhaps a source of shame to some that the technology which would have made the crash impossible had been rejected on these cost grounds.
Equally important to the success of mechanisms like RAIB in building a safe system is a recognition of the Heinrich Triangle. This, remember, is the pyramid of the many near misses, minor incidents and major injuries that sits below every fatality. RAIB investigates all of these things, not just the headline crashes and fatalities. Even if nothing serious ever came of the near misses and minor lapses, understanding and eliminating the could-have-been calamities is vital if actual catastrophes are to be avoided. In 2013, for example, RAIB investigated such incidents as a part on a poorly maintained engineering train working loose, causing minor damage to track; a team of maintenance workers coming within 2 seconds of being hit by a train, when processes in place should have ensured they always clear the tracks with at least 10 seconds to spare; another in which a farmer was given the go ahead to use a manually operated level crossing while a train — which she saw in plenty of time to stand clear — was approaching; and a signal passed at danger on a minor line that had yet to be equipped with a full train protection system. None of these incidents had any consequences for life or limb — but it was only luck that there were not worse outcomes. So, rather than dismiss them as inconsequential, RAIB investigated and made recommendations for revised working practices and improved technology. New maintenance regimes were implemented for the engineering trains; the planning process for work teams was tightened; and a software bug in the signalling system for the farm crossing was identified and quickly eliminated. By tackling the could-have-been tragedies at the bottom of the pyramid, RAIB have stopped the tragedies at the top before they ever happen.
Ladbroke Grove was just one of a series of catastrophic train crashes that occurred during the short tenure of Railtrack as the privatised owners of the railway infrastructure. Before that, British Rail presided over regular train crashes — diminishing slowly in number and severity over time, but a fact of life nevertheless, from the 112 killed at Harrow and Wealdstone in 1952 to the 35 killed in a similar three train pileup at Clapham Junction in 1988. The pre-nationalisation rail companies were worse still, from the death of William Huskisson in 1830 on the opening day of the original passenger railway, through the dark decades of the late 1800s when sometimes rail disasters could be expected monthly, to the railway’s worst year, 1915, when 265 were killed in four catastrophic crashes. And these are merely the numbers for train crashes, not including the poor neglected navvies who built and maintained the lines or the men operating the freight yards. In the early years, such lowly workers were expendable labour, while politicians agreed with the railway companies — in which many owned shares — that safety regulations would be too burdensome a barrier to bigger profits. The railway was a different world.
The last time anybody died on a train that crashed in Britain was on the evening of 23 February 2007 when a Virgin Trains express to Glasgow derailed on mistakenly unmaintained track at Grayrigg in Cumbria, the lead carriage performing an impressive backflip as the trailing carriages rolled down an embankment. Thanks to the sturdy design of the modern carriages, just one person died. The Grayrigg crash happened just 7 years, 4 months and 18 days after Ladbroke Grove. It’s impossible to say “never again”, and we must always guard against complacency, but as that incident fades ever further into history, it has started to feel like train crashes simply don’t happen any more. The world changed, and it only took 7 years.
For the blog it made sense that I let this little extract stand on its own as a story by itself, but really it’s meant to be understood as one piece within a larger story that I assembled early in the year, topped and tailed with an edited version of this story. In it I try to tie together a few disparate strands that I had been thinking about, using as a theme the imagined “different worlds” that Dave Horton talked about and the real different worlds that have come about, in surprisingly short time, in the Netherlands and on the railways. And in it, the 7 years, 4 months and 18 days of fatal train crash free days are contrasted with the 27 days during that period when we can expect there to have been zero fatal crashes on Britain’s roads. Hopefully it might one day be fit to see the light of day…
A couple of years ago, when I had some time to waste flicking through the four decade history of stalled and deliberately ineffective “pro-cycling” transport policies, I created one of my simplest but most enduringly popular posts: a graph of That Cycling Revolution we keep hearing about.
The concept was simple (and crudely implemented) but I think must have made the point strikingly: taking quotes celebrating a “bike boom”, a renaissance of cycling, a grand new policy, or, most absurdly of all, a golden age of cycling and overlaying them on a graph of cycling’s great decline and stagnation in this country.
But of course, we were in the midst of a cycling revolution at the very time! The Olympics were coming! We were going to ride the wave! Sadly, at the time, the Department for Transport traffic survey data that was used as the basis of the graph only reached as far as 2010, when we were merely in the midst of a cycling revolution. So how did 2012′s cycling revolution work out? Last year’s numbers are in and it’s time to look at an updated picture.
(This time, to avoid faffing with crudely adding the annotations in PS, I’ve found the Google Docs annotations functionality, which unfortunately is very limited in the control it gives you over display style (and doesn’t give quite the right feel to the different types of data that crude PS labels gave), so click to embiggen and get the quotes…)
Oh what a change.
As ever, I’ll repeat Dave Horton’s warning here:
there are two clear and present problems which bedevil UK cycling advocacy: one is the requirement to trumpet any and all gains, however minor or potentially imaginary, in order for us to legitimate and reproduce ourselves as advocates; the other is a rush to interpret any sign of growth in cycling as both ‘good’ and a clear sign that investments in cycling are paying dividends, when a wider and more critical analysis might concur with neither.
And as before there are caveats to consider, besides the (pretty much irrelevant to the final results) fact that I normalised GB distances to UK population change. The two in particular that occurred to me being:
Firstly, the annual traffic estimates are based on manual traffic counts for a (large) sample of roads. They don’t include off-road routes like railway paths, which have been slowly appearing over the past three decades. Unfortunately I doubt there are anywhere near enough such routes to make any relevant difference to the national numbers. Of course, in a few places they might make a difference to the local numbers, which brings us to…
Secondly, they are national numbers, and I’m sure people will still want to argue that cycling in their city is booming. In London, for example, there genuinely has been growth in the numbers of people on bikes in inner and central London over the past couple of decades. But at the same time, cycling in outer London plummeted, stabilising only in recent years.
A caveat to the caveat, though. When the CTC put together a map showing changes in cycling commuter share between the 2001 and 2011 census, people were keen to find meaning in the numbers. Why was there an apparent bike boom over here? Why did cycling rates crash over there? But in most of the country, all that the map really showed is the same thing that the DfT’s distance estimates show: that cycling hit rock bottom long ago and the tiny numbers continue to fluctuate — mostly by fractions of mode share percentage points — randomly.
If you did the stats properly, perhaps you could pin a robust narrative to the data — small but significant rural declines to small but significant inner urban gains seems to be one of the more attractive hypotheses*. But you couldn’t make the stories of the cycling revolution – or the policies that were supposedly to make one come about – stick.
(For the data and info on sources, see the Google Doc.)
* but equally you can find evidence that suggests the exact opposite and evidence that recently there’s no nationwide urban/rural trend at all; none of the evidence is all that good, and all it really says is that rates are fluctuating at low levels.
So the Institute of Advanced Motorists have press released the fact that casualties are up on 20mph streets (deaths are down, but they were already in single figures, so that’s random). I thought it might be worth reposting this sarcastic rubbish that I bashed out last time some idiot tried to claim that an increase in casualties on 20mph roads is evidence of their failure.
I heard on the lunchtime news on Radio 4 today the shocking news of an increase in the number of people injured on 20mph streets. Back when there were fewer 20mph streets, fewer people were injured on 20mph streets, they revealed. Now that there are more 20mph streets, more people are being injured on 20mph streets. This road safety intervention, they concluded, isn’t working.
This watertight logic perhaps also explains why BBC News have been so quiet on the destruction of the NHS. Before the NHS existed, literally nobody at all died in any of the then non-existent NHS hospitals. Almost as soon as the NHS was created, people started dying in the newly created NHS hospitals. Clearly the NHS doesn’t work.
Members of the Association of British Nutters will no doubt be getting very excited about these numbers, but before they make rash recommendations they should remember that back before the British motorway network was built, there were literally no people injured on the British motorway network, whereas now that the British motorway network exists, there are lots.
I hope that the main elements of the astonishing innumeracy that went into the BBC story — the failure to put the raw numbers into any kind of useful context, either of the rapid growth in the number of streets with 20mph limits as it has become easier to set the limit (or their changing nature as 20mph starts to roll out beyond quiet residential streets onto busier high streets), or of the far higher number (and, more importantly, rate) of injuries and death on either equivalent 30mph streets or on the same 20mph streets before the speed was lowered — should be obvious. Needless to say, reducing speeds on a street from 30mph to 20mph cuts injuries, regardless of the entirely banal fact that those few injuries which remain will thenceforth be added to the tally for 20mph streets instead of that for 30mph.
So, mockery over, there’s a more important point: should an increase in injuries, if there really had been one, automatically kill off further roll out of 20mph zones?
It beggars belief that the council intend reducing the 30mph speed limit. A limit introduced when there was no such thing as MoT’s, ABS brakes, crash zones on the front of cars and good street lighting.
I can see no justification in spending this money and would dearly love to know who Bristol City Council think it will benefit? It certainly won’t be the youth, disabled or elderly.
James R Sawyer clearly thinks that the 20 zones must be all about safety, as he argues that his ABS brakes and crash zones are already plenty enough to keep him safe as he drives through Bristol at 30. But Bristol have always been clearabout why they’re moving towards a 20mph city:
Councillor Jon Rogers, Cabinet Member for Care and Health, said: “…20 mph zones create cleaner, safer, friendlier neighbourhoods for cyclists and pedestrians. They are popular with residents, as slower traffic speeds mean children can play more safely and all residents can enjoy calmer environment.”
Slower speeds are not a simple issue of cutting crude injury statistics. They’re more about reviving communities which have been spoiled and severed by traffic speeding through them, reclaiming a little bit of the public realm that has been monopolised by the motorcar, and enabling liveable walkable neighbourhoods to thrive. Far from “certainly no benefit for the youth, disabled or elderly”, we know much — some of the research having in fact been carried out in Bristol itself — about the many adverse effects of higher speeds and volumes of traffic, and the loss of shops and services due to car-centric planning and living and the blight of high streets by arterial traffic, on the mobility of those most excluded from the car addicted society, particularly the young, the elderly, and the disabled. If they’re lucky, these people will be forced into dependency on those willing to help them get around; if they’re unlucky, they will simply be left isolated and severely disadvantaged. But of course, we don’t like to acknowledge the existence of the large numbers of people who are excluded from much of our society, culture and economy by our rebuilding the world with nobody in mind except car owners.
The injury statistics cited in the BBC News piece include minor injuries, which is most injuries at slow speeds — little things which don’t require a hospital stay. What are a few more cuts and bruises if it means that thousands of kids are free to walk to school with their friends instead of stuck inside mum’s car? Would we rather keep the infirm all shut up and sedentary with no access to the shops and the services they need, too intimidated by the anti-social behaviour of motorists to cross the road, than risk one person having a fall?
These strands can be tied together by the other piece of context that would have been worth including in the BBC piece: in the same year that injuries in 20mph zones increased, injuries to pedestrians and cyclists in general increased — in part because there are more to be injured. It has always been the case that the great road safety gains that successive governments have boasted of have been won mainly by making streets so dreadful that people find them too frightening, stressful, unpleasant, humiliating or ineffective to walk, cycle, or do anything other than sit in a secure metal box on. Start making the streets a little bit less awful and people return to them.
“The overall results show that ‘signs only’ 20mph has been accompanied by a small but important reduction in daytime vehicle speeds, an increase in walking and cycling counts, especially at weekends, a strengthening of public support for 20mph, maintenance of bus journey times and reliability, and no measurable impact on air quality or noise.”
Like cycle tracks, which people still like to claim increase car-cycle collisions (they don’t) despite before-and-after studies largely ignoring the fact that the point of cycle tracks is to widen bicycle use from the confident and quick witted to the people who were are otherwise too scared, stressed or infirm to do so, so invalidating the before-and-after study design, an increase in minor injuries after speed limit reduction, even if it were really to happen, would be far from proof of a failure.
Postscript, July 2014
The IAM make a thing of the DfT stats showing a 26% increase in serious injuries in 20mph limits and a 9% decrease in 30mph limits. Given that the base figures for the two sets are so different, that amounts to 87 more injuries in 20 zones and 1102 fewer injuries in 30 zones. Of course, the only figures that would really matter (in the absence of a double blind randomised controlled trial) are before/after comparisons of the streets that have switched and/or case-control studies of those streets (at least, for measuring injuries; as I said before, there are other important outcomes to 20 zones besides injury rates). And given that these numbers are not (and could not really be) normalised to the changes in total length of the two types of street, and are influenced by far too many confounding variables, I wouldn’t dream of suggesting that they’re worth drawing any conclusion from. But if you’re intent on drawing a conclusion, given the trend in switching 30mph streets to 20mph streets, a net reduction in serious injuries of 1015 seems like a far more pertinent one than a 26% increase in injuries on 20mph streets.