Monday, 17 December 2012

Car ownership is falling in London but car traffic is falling even faster

The last couple of weeks have seen some interesting figures confirming the decline of car culture in London. First, the 2011 Census results showed, as summarised by London City Cyclists, that the number of car-free households is growing across Inner London. Then the National Travel Survey showed that car travel per person in London fell 22% in just seven years (table NTS9904 here). Finally, as pointed out by Angus Hewlett on Twitter, here's a survey (admittedly from a fortnight ago) showing that "One in seven Britons said they were part of a household which owned a car that was only used occasionally", a figure that rose to one in five in London.

That survey suggests that car ownership has some way to fall yet in London. To get a better sense of this I plotted the trend in distance travelled by car (from DfT table TRA8905a) against the trend in the number of cars (from table VEH0204) for London and England as a whole in the chart below. Both series are rebased to start at 100 in 2000.

What this shows is that in England as whole the number of cars has risen 15% since 2000 and the distance travelled by car just 2%, while in the Greater London area the number of cars has risen 5% but the distance travelled by car has fallen 13%. The leftward turn in both lines is an indicator that distance driven per car is falling in both London and England, but it's falling particularly fast in London, in fact by 15% since 2000. The average car in London drives around 9,100 km per year (down from around 11,000 in 2000), compared to 13,800 km a year for the average car in England as a whole (also down, from 15,400 in 2000).

So it's no surprise that there are lots of 'ghost cars' hardly being driven in London, or that, particularly in the last few years, many Londoners are deciding that it's just not worth the cost and hassle of owning one. I'd expect this trend to continue for some time yet and the number of cars in London to shrink further (though it is worth bearing in mind that across London as a whole there are more cars than there were in 2000). I just hope we use the extra space freed up for useful things rather than just dropping the cost of parking even further.

Tuesday, 11 December 2012

What do homeowners have a stake in?

Today's Census figures showing a fall in home ownership have excited plenty of comment about the struggles of so many people to get on the property ladder. With excellent timing, the IPPR came out with some research yesterday examining some of the knock-on effects of these housing pressures. Jenny Pennington, the author of the research, summarises the argument here. I recommend people read the full report as it has some really good qualitative evidence on the social consequences of high housing costs, such as people having to delay starting relationships or having children. But there's one particular result I'd like to focus on. Jenny writes:
Secure housing also makes a real difference to the way people invest in a particular community. Owning a home increases a person's sense of belonging to a neighbourhood. For example, an individual who has lived in the same home for 20 years without owning it is likely to feel the same sense of neighbourhood belonging as someone who owns their home, but has lived in it for just six years. Young people who did not own their home talked about not really seeing the point of committing to the area in which they lived or getting to know the people they shared a street with.
This conclusion is arrived at through a robust-looking analysis of survey data, and I'm sure it's accurate as far as it goes. I would just caution that it's very hard to control for all the relevant factors here, particularly the crucial one of how long people intend to stay in a neighbourhood. Someone who expects to be moving on in a few years is likely to be less keen to either buy a home (given the transaction costs involved) or get much involved in local community matters. If the average level of 'expected mobility' in the population rose (because more people need to move to find work, for example), then we should probably expect to see both less home ownership and less 'neighbourhood belonging' - but home ownership wouldn't be the causal factor.

That said, I suspect there probably is a positive effect of homeownership on community belonging, even if it is hard to identify empirically. Pure self-interest would suggest that homeowners are likely to be more committed to the improvement of their area, because when you own a home somewhere you are to some extent stuck there (transaction costs again), and the value of your (very large) financial investment will be determined by what does or doesn't happen in its surroundings.

Lest anyone think I'm just being cynical for the sake of it, there is some pretty good evidence that homeowners' attitudes towards community issues are influenced by the expected impacts on house prices. Here's Christian Hilber, writing in the Journal of Urban Economics in 2010:
This paper examines the role of local housing supply conditions for social capital investment. Using an instrumental variables approach and data from the Social Capital Community Benchmark Survey, it is documented that the positive link between homeownership and individual social capital investment is largely confined to more built-up neighborhoods (with more inelastic supply of new housing). The empirical findings provide support for the proposition that in these localities house price capitalization provides additional incentives for homeowners to invest in social capital. The findings are also largely consistent with the proposition that built-up neighborhoods provide protection from inflows of newcomers that could upset a mutually beneficial equilibrium involving reciprocal cooperation.
Translated, what this means is that home owners really do put more effort into building social ties ('social capital investment'), but only really in places where it's harder to build new housing ('more inelastic supply'). One possibility is that this is because in such areas any local improvements as a result of stronger social ties are more likely to result in higher house prices, while in areas with elastic supply rising demand results in more new homes and no effect on prices. It's worth noting that Dr Hilber previously found that in Massachusetts even elderly homeowners without kids tend to vote for (and pay for, through taxes) investment in schools because it increases the value of their home.

Many people might say there's nothing wrong with any of this, and that if home ownership gives people a financial incentive to care more about their neighbourhood then so much the better for home ownership. My concern is that it also seems to give people a financial incentive to oppose new housing supply in their neighbourhood, as new development may reduce the value of their home (either through a supply effect or the amenity impact of extra housing) or, as Dr Hilber suggests, upset the social balance they have helped create. If homeowners are really less likely to be socially virtuous when housing is plentiful then it sounds like a society with high levels of home ownership and strong social ties may also be one with a persistent housing shortage.

And indeed, that's kind of what the basic numbers suggest. Surveys show that a sizeable majority of home owners say they would oppose new homes being built in the local area, while private tenants are basically split and social housing tenants are in favour of new housing. And over the long run, the rate of new housing supply has fallen while the rate of home ownership has risen. The graph below charts one against the other for England as a whole, starting in 1972 and ending in 2011. Throughout most of the 1970s we were building around two new homes for every new household, but over time, the rate of building fell as the rate of home ownership rose. There was obviously a lot of other stuff going on at the time so I'm not categorically claiming a causal relationship, but it's not a particularly positive picture either.

To sum up, I'm not sure home ownership gives people a stake in 'society' so much as it gives them a stake in their local neighbourhood, which is not the same thing, especially if one way to 'help your neighbourhood' is to prevent new homes being built there. That may make sense from a household's perspective (in fact for many people it certainly does) but that doesn't mean it makes sense for society as a whole.

Monday, 3 December 2012

A few notes on getting Britain cycling

The All Party Parliamentary Cycling Group is holding an inquiry into how 'Get Britain Cycling' and they want evidence by the 5th, so the following is just some notes for my submission, mainly to get me to write something down rather than endlessly opening more browser tabs.

There is a large latent demand for cycling that is not being realised because of safety concerns
Just 2% of trips under 2.5km are cycled in the UK, compared to 14% in Germany, 27% in Denmark and 37% in the Netherlands (Pucher and Buehler).

Research by Transport for London found that only 7% of 'potentially cyclable' trips in London were currently cycled, and that safety (the lack of it, more precisely) is the greatest barrier to cycling.

A large DfT survey carried out in December 2009 found that:
  • 60% of people who can ride a bike say it's too dangerous for them to cycle on the roads, including 71% of women and 72% of those aged 60 or over.
  • 52% agree they would cycle more if there were more dedicated cycle paths (30% disagree).
  • 86% of people say that cycling is the least safe form of transport.
In 2011, two thirds of people in the British Social Attitudes survey said they were not very or not at all confident about cycling on the roads (DfT table).

Research shows that high quality, separated infrastructure is safest and most popular
  • "The key to achieving high levels of cycling appears to be the provision of separate cycling facilities along heavily travelled roads and at intersections, combined with traffic calming of most residential neighbourhoods". Pucher and Buehler, 2007
  • "Consistent with gender differences in risk aversion, female commuter cyclists preferred to use routes with maximum separation from motorized traffic. Improved cycling infrastructure in the form of bicycle paths and lanes that provide a high degree of separation from motor traffic is likely to be important for increasing transportation cycling amongst under-represented population groups such as women". Garrard et al, 2008.
  • "The greater the physical separation from motor vehicle traffic, the higher the women's share of cyclists". Pucher et al, 2010.
  • "The lower risks on quiet streets and with bike-speciļ¬c infrastructure along busy streets support the route-design approach used in many northern European countries. Transportation infrastructure with lower bicycling injury risks merits public health support to reduce injuries and promote cycling". Teschke et al, 2012.

We have a severe shortage of the right kind of cycling infrastructure
The under-utilisation of bikes for short trips, the survey findings on subjective safety and the high casualty rate in places where cycling is more popular all point to a widespread and severe lack of high-quality cycling infrastructure in Britain.

To get Britain cycling in safety central government must urgently address this deficit by
  • Revising DfT cycle design guidance so that high-quality, Dutch-standard cycling infrastructure is given the highest priority;
  • Making available sufficient ring-fenced funding to introduce high-quality separated cycling infrastructure in towns and cities across Britain in the next five years;
  • Allocating this funding through a competitive bidding round in which funding goes to the proposals that combine the highest quality design with the greatest impact in terms of current and potential cycling demand.
Leadership from central government is vital 
Many local authorities lack understanding or expertise in designing for cyclists, and in many parts of the country so few people cycle that they hardly impinge on local political consciousness at all. The fastest and best way to get local authorities to act is for central government to provide the right funding and the right guidance.

Higher rates of cycling will save people money and bring wider benefits
  • In total, people in Britain cycle about 3.1 billion miles a year (DfT). 
  • But on a per person per day basis, people in the Netherlands cycle about 12.5 times as much as those in the UK (Pucher and Buehler). 
  • That suggests that if people in Britain individually cycled as much as the Dutch we'd cover about 39 billion miles a year. 
  • According to these figures from Edinburgh cycling saves you between 55p and 60p per mile compared to driving, taking all costs into account. 
  • So people in Britain are already saving almost £2 billion a year by cycling instead of driving, but if they cycled at Dutch rates they would save over £20 billion.
  • These figures may be a touch too high, since there are other (and usually cheaper) alternatives to cycling than the car. They're also fairly dependent on volatile variables like petrol prices.
  • But they also exclude the wider social and environmental benefits of cycling and driving, which are very large (even taking into account higher average casualty rates from cycling), perhaps three times as high as the private cost savings (Figure 3.1 here).
  • So it's probably fair to say that achieving cycling rates akin to those in the Netherlands would deliver private and social benefits to the value of tens of billions of pounds. 

Saturday, 24 November 2012

Map of 2001-2011 population change in London

Update: Those intelligent people in the Intelligence team at the Greater London Authority have now made a better map of population change between 2001 and 2011, which I think you should look at rather than mine (there's more GLA analysis of the Census here). 

The GLA map is better because (a) it uses ward boundaries, which unlike the statistical boundaries I used have not changed over time and therefore offer a like-for-like comparison; (b) it compares Census 2011 population to the 2001 mid-year population, which the GLA thinks is a more reliable figure than the 2001 Census figure, and (c) it's interactive! So I've put my map below the fold here, just for reference.

Thursday, 1 November 2012

The gender dimension of road danger

This BBC article about 'black box' devices in cars which monitor your driving for insurance purposes features lots of standard-issue outrage from drivers who can't see why how badly they drive should be anyone else's business but it also touches on the interesting issue of whether female drivers are safer than males. You don't have to look too hard to find plenty of commentary on this topic, but hard facts are more difficult to come by. Here's something from 2004:
Male motorists were responsible for 88% of all driving offences that resulted in findings of guilt in court in England and Wales in 2002, the Home Office statistics showed. Furthermore, men committed almost all the most serious offences, such as causing death and dangerous driving: women committed just 6% of the death or bodily harm offences in 2002 and just 3% of dangerous driving offences. Men were also responsible for 96% of vehicle thefts and 97% of offences relating to motorcycles.
Those are pretty huge differences, but perhaps, and I'm just speculating here, partly down to different treatment of men and women by the justice system. You can also look at the different rates at which men and women are involved in collisions resulting in injury, with the caveat that the figures don't necessarily imply anything about who's at fault. I looked at DfT's 2011 road casualties data, and found that in 85% of collision where a pedestrian died the driver of the vehicle (mostly cars but also vans, motorbikes, HGVs and a couple of bikes) was male, compared to 71% of cases resulting in serious pedestrian injury and 69% of cases resulting in slight injuries. This table suggests that men account for about 65% of the miles driven in Britain, so they do seem to have a higher rate of involvement in pedestrian casualties (trying to calculate rates for all kinds of collisions is more complicated).

What was most interesting to me is that males also account for a higher share of pedestrian casualties too: 68% of fatalities, 60% of fatal or serious injuries and 57% of slight injuries in 2011, according to this table. Other figures show that men and women do roughly equal amounts of walking, so these numbers do seem to provide some support for the idea that guys take more risks - or maybe just have worse judgement - than girls whether they're in cars or on foot.

The wider issue is that men also have more influence over transport policy and road safety, with the result that the issue is treated more as one of personal responsibility than as one of public health. The same cognitive biases that tell us we should be able to look out for ourselves ensure that we basically can't.

Sunday, 28 October 2012

Last reminder to respond to TfL's road safety plan

It's been a busy month so I haven't been able to properly follow up the previous two posts about TfL's proposed road safety plan. The consultation closes on Wednesday the 31st (having been extended at the request of the London Assembly) so there's still time to get your responses in. Here are a few good responses from other sources which you might find useful:
  • Rachel Aldred, who says "abandoning a cycling target is going in the wrong direction", and calls for "a clearer strategy to reduce cycling KSIs, focusing on the known causes of danger and doing more to test, utilise and evaluate policies and strategies adopted in countries that are leaders in this area."
  • Southwark Council, who say "The cycling specific actions in this plan are too few and too vague" and that the Cycling Safety Action Plan it relies on is "too ambiguous to be accountable". They also say "More needs to be done to improve road safety for cyclists and this plan does not suggest any substantial new measures".
  • The City of London. This response was drafted by City officers and I don't know if their members amended it before submission. Again, the vagueness of the plan comes in for criticism: "In many cases the timescales are vague, there is no indication of relative priority and, critically, there is no indication of how much the actions will cost or where funding will come from". The response also calls for deployment of technologies such as "intelligent speed adaptation systems – for example, trialling this in TfL and City fleets; rolling out average speed technology in speed cameras; converting speed cameras to enforce 20 mph speed limits". The proposal for a single casualty reduction target that covers all modes is opposed because it "could be achieved through improvements to transport modes that are already much safer" But I thought the most interesting bit was:
    Specifically it is questioned whether there are sufficient new actions – as opposed to continuation of existing actions – to protect cyclists, such as measures to physically separate cycle traffic from motor traffic on busy roads and/or the removal of motor vehicles (or certain classes of vehicle such as lorries or buses) from key cycle routes at busy times.
    That's kind of surprising to hear from the City in light of their proposals to remove cycle lanes at key junctions. Maybe there's more internal disagreement on these issues than we think.
I think those extracts sum up most of the issues I have with TfL's plan. Mainly I'm still struck by how unambitious it is, and how it looks nothing like the product of an organisation determined to transform the way it approaches road design and cycling provision, which is how TfL have taken to describing themselves of late. Whatever your own views, I hope you will send them a response before Wednesday.

Wednesday, 24 October 2012

Urban expansion: learning from 19th century London

Paul Collier says that African cities should learn from the example of 19th century London when it comes to housing policy. London was able to build decent housing for working people because its building regulations weren't onerously high, because landowners split their land up into separate plots for small firms to build out while retaining ownership themselves, and because the legal system of ownership and tenure was clear enough to allow building societies to lend with confidence.

All good points, but I would just a couple of things. First, 19th century London also benefitted from rapidly falling transport costs, which enabled development to take place on greenfield land. Stagnation in transport technology makes it harder to keep expanding the urban frontier and compels us to try and redevelop existing urban areas.

Also, it's not just African cities but 21st century English cities which could learn from the example of Victorian London, in particular on the land ownership front. What usually happens these days is that a developer buys a large site and then waits for the most opportune moment to develop the whole thing, which can take a long time. This arrangement means you are basically creating a local land monopolist, with all the problems that entails. Ideally, government should instead try to split the task of building the site out between a number of smaller firms, who would then be competing against each other, which should raise both the timeliness and the quality of development. Obviously this is much harder when government doesn't own the land, although the German practice of umlegung (land assembly) seems to be a reasonably close approximation.

Sunday, 14 October 2012

If you like your neighbourhood so much then let more people live there

Matt Yglesias has an excellent post here about the lovely city of Santa Monica, which prides itself on its greenness yet has seen barely any population growth in recent decades despite sky-high house prices.

For Santa Monica you can subsitute any number of nice, exclusive places in the US and across Europe. Here in London we have an excellent example in the Royal Borough of Kensington and Chelsea, where the average house price is over a million pounds (pdf) but where the population and the number of households actually fell, albeit only slightly, between the 2001 and 2011 censuses compared to an increase of 8.3% across London as a whole (xls).

Demand for housing in K&C is clearly through the roof, so how come its population isn't growing? The reason is that planning policy, backed up with overwhelming political support from borough residents, makes it very difficult to build any new housing in the area. So very little does get built, so rising demand just pushes up prices.

K&C is a somewhat extreme example (70% of it is in a conservation area!) but the general pattern is widespread. More people want to move to urban areas to be closer to job opportunities or to avail of improvign urban environments, but the people who are already there don't want their neighbourhood to change so they campaign against new housing developments, and politicians dutifully vote those developments down. The supply shortfall pushes up prices, so only the richest can afford to move in and those less well-off either stay put or move to somewhere less nice and/or further out.

I think this is quite a bad situation, because it results in affordability problems, greater segregation by income and environmentally damaging urban sprawl as housing supply is diverted to places further away from jobs and services. And indeed, you hear a lot of concern about these issues in urban political discourse - but what you generally don't hear is any connection being made with all those anti-development crusades that contribute so much to the problems.

Of course there may be downsides to densification of existing urban neighbourhoods in response to rising demand. A lovely neighbourhood may not look quite as lovely when it's had some buildings replaced or some blocks of flats added. Personally I think these things can go either way and some areas would be much improved by densification, but I also think these basically aesthetic considerations are just not that important compared to the effect on people's lives of making more housing available in places where they want to live.

At its root, this is an issue of social justice and of personal ethics. People who care about social justice should be worried about a political process which gives all the power to people who already inhabit a neighbourhood and none to the people who would like to (see Matt Yglesias again). And people who think of themselves as ethical should ask themselves whether they can justify excluding others from enjoying the same neighbourhood they like so much, while adding to our already serious problems of affordability and car-dependent development.

Tuesday, 9 October 2012

A land value tax would be unpopular for the same reasons that it would be great

I was surprised a while back to find that the Liberal Democrat conference policy paper on housing included a call for a land value tax (LVT), because the current party leadership shows absolutely no interest in implementing one. But then LVT has long been a cause beloved of earnest policy wonks and loathed by politicos. I'll get to why that is in a moment, but first it's worth rehearsing what I like to call the neoliberal-environmentalist-progressive case for an LVT.

An LVT is a tax on the value of land, excluding the value of anything built on it. The logic is that the relative value of different plots of land is nothing to do with the landowner's activities but is purely a product of their locations and the access they grant to amenities, infrastructure and other 'locational goods'. And because land is fixed in supply and location, taxing it doesn't have the distortionary effects that taxing income or consumption might. So because the community effectively creates the value of land, the community should also draw the benefit rather than let landlords get rich by doing nothing.

Part of the attraction - for policy wonks - of an LVT is that it would provide an incentive for valuable land to be used for its most productive purpose. So if you own a plot of land in a great location, the high tax on it gives you a very strong incentive to get as much money out of that site as possible, which might mean building offices or housing or whatever - the point is that you do with that land whatever maximises its value, subject to whatever constraints the planning system sets . This outcome is good for the landowner (who reduces their net tax bill), good for the government (who gets the tax revenues) and good for whoever ends up occupying the buildings on the land, as they get homes or workplaces they would otherwise not have.

But as Duncan Stott Stoddard points out on the IEA blog, there is a significant problem here, in that current planning policy in this country (and most others) is mainly concerned with restricting landowners' abilities to maximise income from their land by building stuff on it. Building something a bit taller than the surrounding buildings is basically illegal across large swathes of this country, as is switching uses from residential to commercial or whatever. Retaining these extremely strict regulations on land use would negate much of the benefit of an LVT. In fact, it would arguably make an LVT quite unjust, in that you would be increasing some people's tax bills while preventing them increasing the income from their land to compensate.

So as Duncan says, an LVT should really go hand in hand with looser planning regulations. That way you maximise both the benefits of an LVT and the benefits of looser planning - the latter because if you loosen up planning policy without an LVT you are basically enriching landowners (by increasing their potential income) again without them having done anything to deserve it. And allowing landowners with valuable land to build lots of housing on it also means that if they pass the cost of their LVT onto those who occupy the land (i.e. tenants or apartment owners), then obviously the more occupiers there are the lower the cost is for each of them. This can mean that the per-household LVT is significantly lower in city centres than it is in the suburbs - which is also a benefit, since people living at higher densities are imposing fewer costs on the community in terms of infrastructure requirements, energy use and so on.

So a combination of a land value tax and looser planning regulations would very likely deliver cheaper housing, more tax revenues, a fairer distribution of wealth, a shift in the tax system away from distortionary income taxes, and a more sustainable and energy-efficient pattern of land use. Who wouldn't want that?

Lots of people, it turns out. In particular you've got all those homeowners who bought into a neighbourhood which then improves around them, driving up the value of their property and generally making them very happy with their lot. Coming along and telling them that actually they should pay a bit more for their good fortune and perhaps consider building a block of flats on their land will probably have this large and vocal constituency reaching for the pitchforks. But as well as the people who have got lucky in the property market, an LVT will probably also incite the ire of anyone who aspires to get lucky in the property market, which is to say pretty much everyone.

After all, just about everyone everyone wants to be that person who buys a property and sees it rocket in value through no skill or effort of their own. Yes it's unearned wealth and so policy wonks will say it raises important issues of social justice and economic efficiency and yadda yada, but everyone wants to achieve huge wealth, preferably without earning it. An LVT says nobody should get away with amassing unearned wealth through locational good fortune without paying some appropriate fee to providence.  In other words, it is an attempt to put a stop to free lunches via the property market. But people like free lunches, and if they don't currently have access to one they like to think that some day they will. And that, it seems to me, is why politicians are scared of land value taxation.

Neverthless, I do think the world would be a better place if we had more land value taxation, and it could happen if enough people get behind it and crank up the machinery of persuasion. Environmentalists, progressives, tall-building aficionados and tax reformers should recognise the benefits, hold their noses and start forming coalitions to lobby for this, because our leaders are going to require a lot of persuading.

Wednesday, 26 September 2012

We choose how congested our roads are

This BBC article about traffic congestion in Sao Paulo carries on like 180km traffic jams are an inescapable fact of life there and congestion is an insoluble problem. They even find a professor of engineering and transport from a Sao Paulo uni to say that "No city in the world will ever manage to end congestion".

Completely ending traffic congestion may be very difficult, but there are certainly cities who have reduced it substantially by doing things which Sao Paulo has chosen not to do. Congestion charging in Stockholm, Singapore and London has sharply reduced the level of traffic in their inner cities, and there is no doubt that if they were to whack up the prices that traffic would fall even further. Many cities have also built comprehensive, high quality rail systems, and given buses priority express lanes on main roads. But in Sao Paulo, instead of a congestion charge they introduced a rotating car number-plate ban which reduced traffic in the short term but mainly encouraged people to buy more cars. The metro system is far too small given the size of the city. And historically their buses haven't been given enough priority over other traffic and so suffer from the same congestion as cars. Hence, huge traffic jams.

I'm not suggesting these are easy choices, especially for a rapidly expanding city like Sao Paulo. Most cities are not fortunate enough to have built a huge underground system over a hundred years ago when it was nice and cheap, like London did. Sao Paulo now has a growing bus rapid transit system and big plans to expand the metro, but because Brazil is a democratic country where most people have the right not to be turfed off their land, building vast infrastructure projects is much harder and slower than it is in, say, China. Likewise, it's not easy to find the money to build a subway network big enough to adequately serve a city of 20 million people, or to convince drivers that they should pay to use roads they previously used for free. Those kinds of things are very hard, which is probably why more cities don't choose to do them.

But one reason they're hard is that many people are not convinced they are worthwhile, and that in turn is partly because the public discourse around these issues seems wilfully uninformed. There are solutions available which are workable and demonstrably effective. It's one thing to consider and reject them, but to pretend they don't exist is something else altogether.

Monday, 24 September 2012

Mapping pedestrian casualties in London

The Department for Transport publish full data on recorded road casualties on, and I've been playing around with the data a bit recently, partly as a way of learning some new software skills.

The map below (best viewed at full size) is one result, and shows serious and fatal pedestrian casualties in London in 2011 which were the result of collisions with bikes (in red) or cars (in turqouise). Bigger circles represent fatalities and smaller ones serious injuries.

In total there were 980 serious or fatal pedestrian casualties in London in 2011, of which 33 resulted from collisions with bikes (one fatal) and 609 resulted from collisions with cars (38 fatal). The remainder resulted from collisions with motorbikes, goods vehicles, buses and other vehicles, but I didn't show them as I wanted to keep it simple and was mainly interested in comparing cars and bikes.

Techie details: I downloaded the csv data for casualties, accidents and vehicle records for 2011, used R to merge and filter the data, used QGIS to convert the data to a shapefile, and used Tilemill to combine that shapefile with some other layers, apply stylings and export to PNG. Tilemill does some puzzling things like leaving some of the markers brigher than others for no apparent reason, but hopefully that will be ironed out in future versions.

Problems with comments

Apparently some comments are not appearing on the site, even though I can see them in the Blogger admin system. This seems to be a problem with Disqus not picking up comments made via the mobile version of the site. I'm trying to fix it at the moment. I think this only affects one comment so far, and it hasn't been lost.

Also, some readers have said they can't leave anonymous comments on the site. You should be able to - just post as a 'Guest' and enter a made-up email address.

Saturday, 22 September 2012

Reviewing TfL's road safety plan, Part 2: Which target?

This is the second post looking at Transport for London's draft road safety plan, which is out for consultation here until the 28 September. Whether you agree with the draft plan or not I encourage you to respond to the consultation: 2,805 people were recorded as killed or seriously injured on London's roads in 2011 alone, so this stuff matters.

In the first post I reviewed TfL's take on recent casualty trends in London, noting that the target to halve the number of cyclists killed or seriously injured ('KSI', in the jargon) on London's roads was missed, with the number of KSI falling by just18% compared to a 57% drop in overall casualties (see chart below from the last annual report).
TfL argued that this failure was due to the enormous growth in cycling over the same period. Which is largely true - but then why not set a target to reduce the rate of cycling casualties per trip or per kilometre cycled? As I mentioned earlier this month, TfL have recently calculated casualty rates per 100 million kilometres travelled by different modes in London, and the Department for Transport also do a similar calculation by region, so the information is available to monitor such a target. And according to the Road Danger Reduction Forum, TfL have said in the past that they intended to adopt rate-based casualty reduction targets to deal with this problem of absolute casualty targets being affected by changes in trip rates. Finally, the government's new road safety framework proposes rate-based casualty reduction targets at the national and local level (see p.72 here).

These are all good reasons to adopt a target to reduce the rate of cycling casualties per distance travelled, and similar targets for other modes. But TfL have decided against such a target; in fact they have decided against having any target of any kind to reduce cycling casualties. Instead, they propose a target to reduce the absolute number of all KSI road casualties by 40% by 2020 from the base period of 2005-09.

TfL describe this proposed target as 'challenging' (p. 26 of the plan), but when you look at their own chart it doesn't really seem all that challenging.
The number of serious or fatal road casualties in London fell by more than half in the nine years between 2001 and 2010, and reached a low of 2,805 in 2011. TfL are proposing to reduce it to 2,176 by 2020, which would be a reduction of 22% over the next nine years, comparatively a much slower rate of reduction.

So this proposed target sounds distinctly unchallenging, even if you assume, as I think TfL must be doing, that traffic starts growing strongly again during the period. Another partial explanation is offered on the same page, when TfL say that this target "is based on the assumption that the existing road safety programme continues, but does not include the effects of any new measures". In other words, TfL aren't including the effect of any improvements from the junction review or any attempts to 'Go Dutch' in terms of cycling infrastructure. Whether that is because they don't know what to expect from these policies, or know not to expect very much, is not made clear.

All this stuff about targets might seem like fairly irrelevant bureaucracy to some, but I think it does matter, because genuinely challenging targets with a high political priority attached do in practice lead to the re-allocation of resources, and because they can help to focus minds and change cultures within bureaucracies. TfL have recently given hints that they are genuinely changing their policies and practices to reflect a new focus on reducing road danger, but this draft road safety plan and the main target proposed don't seem to reflect any of that. I think if cycling is to get significantly safer in London then we need to focus TfL's minds on reducing the casualty rate, and the road safety plan is a good place to start with that. If you agree, write to them and say so before the 28th.

Monday, 17 September 2012

Reviewing TfL's draft road safety plan

Transport for London are currently consulting on a draft new Road Safety Plan for London which sets out proposed targets and policies for the period up to 2020. The consultation period closes on 28 September and I strongly encourage everyone to respond - there is a questionnaire you can fill out to make it a bit easier.

I plan to do a few posts analysing the draft plan in detail, as it's quite an important document. This first post looks at how TfL describe recent trends in road safety in London; the next one will probably focus on the target they propose to adopt, and the last will look at some of the policies they do and don't propose to implement.

The number of road casualties, including the number involving fatal or serious injuries (crudely abbreviated in the jargon to 'KSI' for 'killed or seriously injured'), has fallen substantially in London over the last couple of decades, and TfL are rightly keen to highlight this. The headline figure is that the number of KSI casualties in 2010 was 57% lower than the average figure for 1994-98, which has been used as the baseline until now. This means that the overall target in the original London Road Safety Plan (first published in 2001 and then updated with tougher targets in 2005), for a 50% reduction in KSI casualties by 2010, was met.

But that first Road Safety Plan didn't just set an overall target for road casualty reduction. There were targets for individual modes too, to try and ensure that casualties were reduced across the board. Following the 2005 review, these mode-specific targets were:

  • A 50 per cent reduction in the number of cyclists and pedestrians killed or seriously injured 
  • A 40 per cent reduction in the number of powered two-wheeler users killed or seriously injured

There was also a specific target to reduce the number of children killed or seriously injured by 60%.

The targets for KSI casualty reductions among cyclists and motorcyclists were not met. As the chart below (from the last annual monitoring report) shows, the number of cyclist KSI casualties fell by only 18% and the number of motorcyclist KSI casualties by 34%.

Strictly speaking, then, the original road safety strategy failed to meet its targets. TfL, however, argue that the failure to hit the targets for cyclists and motorcyclists was due to large increases in both cycling and motorcycling in London, and that the underlying casualty rate for both modes actually decreased.

I don't know much about motorcycling trends but over the longer term it is certainly true that the cycling casualty rate has fallen in London - see, for example, the chart below produced by from TfL data.

There are a few things you could say in response to this argument. The most obvious is that they can't have it both ways - TfL's target was to reduce the absolute number of cycle and motorcycle casualties, and if you go back to the 2001 road safety plan you can see that this target was set in the knowledge that use of both modes was rising. Secondly, if they now think that the rate of casualties per trip or per mile travelled is more important, then why not make that the target, or better yet set a target to reduce both the rate and the number of casualties? Thirdly, it is clear from the chart above that the cycling casualty rate pretty much flatlined between 2004 and 2010. And that trend doesn't include 2011, which saw a 22% increase in fatal or serious cycling casualties, probably outpacing the growth in cycling journeys. Again, if the cycling casualty rate is so important, isn't the record of the last several years rather worrying?

I'll look at some of these issues in the next post, which is about what target should be set. For now, I'd encourage everyone again to read the proposed new plan themselves and respond to the consultation.

Tuesday, 11 September 2012

More cycling than car traffic in central London during the Games?

Just a quick post speculating on a couple of interesting bits of info about transport trends in London. First, according to @bitoclass on Twitter TfL have said that cycling in London increased 22% during the Olympics (presumably compared to last year). Second, TfL have also said that vehicle traffic in central London fell considerably during the Games period, though I haven't seen any firm figures. Third, recall that even before the Games car traffic in central London was falling and bike traffic rising, with the two looking likely to converge pretty soon:

Putting these together, my guess is that cycling accounted for more journeys than cars in central London during the Games period, for the first time in probably 60 years or more. Quite a milestone if so.

[Update: Paul (@bitoclass) has kindly posted a pic of the TfL presentation slide which was the source of his factoid:

So traffic in central London was down by 5-10% in August this year compared to August 2011, and it was cycling across the Thames bridges that was up by 22%. In recent years, growth in cycling across the Thames has lagged slightly behind growth in central London (see table 8 on p.20 here) so it's quite possible that cycling in central London grew by 25% or more.

In any case, we'll probably have to wait until January or so for TfL to update the trend in my chart above. From a policy perspective, perhaps the more interesting question is whether these short-term changes in travel patterns will persist. Cycling through central London yesterday it certainly felt like the vehicle traffic was still very light, but in the absence of any more restrictions I would expect it to creep back to something close to pre-Games levels over time. Or perhaps it won't, if cycling levels stay high - after all, it does seem like once people make the leap to start cycling that a lot of them find it works for them, and in one way or another the Games have probably encouraged plenty of people to make that leap.]

Monday, 10 September 2012

The fatal/serious bike casualty rate per km in London is 30x that for cars; And why bikes need more space because they take up so little

TfL have published a study (under 'Research reports' here) entitled 'Levels of collision risk in Greater London' that I think only gets really interesting on the very last page. Table 4.10 on that last page includes what I think are the first TfL calculations of casualty rates per kilometre travelled in London for different modes of transport. By combining the number of casualties in 2010, estimates of total distance travelled by each mode and assumptions on the average occupancy of each mode, they come up with the following figures for the rate of fatal or serious casualties per 100 million 'passenger kilometres'.

In case you can't read the numbers, they are 73.9 for bikes, 84 for motorcyclists, 2.5 for cars and taxis, 1.0 for buses and 0.4 for goods vehicles. So some good news for our put-upon HGV drivers there. The other interesting thing (okay, maybe only to me) in that table are the TfL estimates for average occupancy of different modes. They say the average car has 1.2 occupants, the average bus 16.6, the average bike just 1 (what, no backies?). Bear in mind that TfL already assume (table 1 on p. 67 of this PDF) that on average a bike takes up just 20% of the road space that a car does (in technical terms it has a 'PCU' or Passenger Car Unit of 0.2), a bus takes up twice as much, and so on. Put these two sets of numbers together and you get a figure for 'Persons per PCU', which is basically a measure of how efficiently each mode of transport uses road space.

Persons per vehicle PCU per vehicle Persons per PCU
Cyclist 1 0.2 5
Motorbike 1 0.4 2.5
Car/taxi 1.2 1 1.2
Bus/coach 16.6 2 8.3
Goods vehicle 1.3 1.65 0.8

Going by these figures, buses use the road space most efficiently (NB none of this includes energy efficiency) and cars the least efficiently (goods vehicles are there to carry goods not people so this measure has fairly limited application to them). Referring back to the figures on casualty rates, we can conclude that buses are both very safe and very space-efficient, which is great, while bicycles are very space-efficient but (relatively speaking) much less safe, which is bad. Obviously cycling could be a lot safer if London had cycling facilities like they do in Amsterdam, Copenhagen, Berlin, Stockholm and various other European cities. The high space-efficiency of cycling is, I think, just another reason that TfL should be copying what those cities have done - that is, giving bikes more space in part because they take up so little.

Monday, 3 September 2012

Robocars will change everything, somehow or other

I've seen very little discussion in Britain about driverless cars (or, if you prefer, robocars), but plenty in the US (see this and this, for example). As this long article in the Economist says, the technology has come a long way in a relatively short time, and it seems inevitable that driverless cars will start grabbing sizeable market share at some point in the next ten or twenty years. As detailed in that article, the implications could be profound. Cars driven by machine promise to be significantly safer than the human-driven variety, mainly because they will have a better sense of their own surroundings and can be programmed to not take any stupid risks. In fact, some of the technology is already in use as 'driver assitance' add-ons for existing car models:
Volvo already sells a popular driver-assistance option called City Safety for around $2,000, for example. It slams on the brakes if a distance-measuring laser or camera detects a vehicle or pedestrian in the car’s path. City Safety can prevent collisions completely at speeds of up to 30kph (18mph), and at higher speeds it softens the impact.
The other reason that driverless cars will be safer is that many people will recoil at the very idea and demand draconian safety regulations to allow them on the street. For example, they could be programmed to drive below the prevailing speed limit on every street, and to have 'black box' devices recording camera,  sensor and movement data (the Economist says the latter is already a requirement for robocars in Nevada). Combine that with software that stops the car whenever a pedestrian steps in front of it and you would have a total revolution in city transport. Currently pedestrians and cyclists are afraid of cars because we don't know if they will stop for us, so we cede the streets to them. But if you knew that a car was not going too fast and would stop for you, what's to prevent you stepping out to cross the road in front of it? This is the kind of technology that would make the fantasised, pedestrian-ruled version of 'shared space' actually a reality.

Unfortunately, that's also the reason why all shared space schemes would probably be removed as quickly as possible. Nobody in a driverless car would want to sit there like a lemon while pedestrians merrily parade past in front of it. After all, if you clear the road of everything except other driveless cars these things will be able to go very fast. Roads that feature cyclists weaving in and out of traffic will be awful for robocars, while Dutch-style segregated lanes will be just peachy. So if the technology takes off, expect to suddenly see a lot of enthusiasm for roads that completely segregate cars from bikes and pedestrians.

Expect big changes in how we relate to cars too. Taxis might become either obsolete, if everyone owns their own robocar, or universal if nobody does (they just won't have taxi drivers). After all, taxis are expensive largely because they have to transport the taxi driver around the whole time even when there are no passengers. Eliminate that fairly hefty weight and they could become economical for everyday use, so why own your own?

The technology is likely to be transformative, in other words, but it's not completely clear in which direction (I haven't even mentioned the implications for inter-city transport, which are likely to be just as huge but more predictable). Maybe we will see cities sort themselves into two camps, one of which imposes speed limits on robocars and lets cyclists and pedestrians boss them around, while the other segregates uses, punitively cracks down on jaywalking and tries to speed as many cars through their streets as possible. The strange thing about driverless cars is that they seem like they could deliver almost every urban transport utopia you care to imagine, and some of the dystopias too. [Update: Speaking of which, by popular demand (two people on Twitter) here's Johnny Cab!

The amazing fall in urban crime rates, and the downside

The Economist has an article about the sharp decline in crime in American cities since the early 1990s, noting that there is no consensus over what caused it. This disagreement isn't that surprising since so many factors may be contributing to crime at once, and since the debate also has some ideological and political significance.

But it is really worth emphasising just how large has been the drop in crime in US cities, because it's important not just on its own terms but for what it says about where our cities are headed. The longest reliable historical record of crime in US cities is probably the homicide rate in New York City, which the late Eric Monkkonen compiled for every year between 1800 and 1999. You can find his data series here. It includes not just the number of homicides but the rate per 100,000 residents, and I have updated the series to 2011 with homicide data from the NYPD and population data from Wikipedia

I think there is good evidence for the theory that lead poisoning (from car exhaust and lead paint) had a lot to do with these trends, partly because it helps explain why crime rates fell not just in the US but across Europe too (see Kevin Drum on this subject, including relevant links). I'm sure improvements in policing helped too. But in a way what caused the fall in crime is less interesting than what knock-on effects it will have.

People understandably put a high value on safety and are willing to pay a price premium to live in low-crime areas. So you would expect the fall in urban crime levels to have contributed to higher urban house prices, and at least in the case of New York you would be right - this research estimates that falling crime rates explain about a third of the mid-1990s increase in NYC house prices.

These price rises show that people really value the safer urban environments created by lower crime. But higher housing costs may not be good news for everyone, especially tenants facing higher rents. If New York City had built a lot of new housing to cope with rising housing demand it would have been able to moderate (but probably not eliminate) these price increases and allow more people to enjoy living in a great city with falling crime rates, but instead higher demand fed straight into higher prices. It would be tragic if this pattern was repeated elsewhere and low-income people pushed out of cities just as they finally become more liveable.

Friday, 31 August 2012

Land values and urban history

Via the Urban Demographics blog, here's a short video of Dr Gabriel Ahlfeldt of the LSE discussing his analysis of a unique dataset of land values in Chicago over time. Apart from looking pretty, this kind of analysis is of great interest to urban economists since land values are both fundamental to understanding cities and very difficult to observe in practice, because the value of land is usually mixed in with the value of structures on it. The data Dr Ahlfeldt analyses manages to separate the two out, allowing us to see how much people are willing to pay for 'pure' location as distinct from whatever happens to be built there.

You can see from the video that land values are very high in Chicago's central business district but then drop off sharply as you move out, a sign that people will pay a very premium to locate their home or workplace (mostly the latter, in this case) in that spot. And as Dr Ahlfeldt says, that particular location has been far more valuable than any other in Chicago for the whole period covered by the data.

So even though vast numbers of boats carrying corn, lumber and pork no longer come and go via Chicago's small harbour on Lake Michigan, the legacy of that waterborne trade and the density of businesses and institutions that built up around it can still be seen in the pattern of industrial and commercial location today. This suggests a very important role for path dependency, history and perhaps chance in explaining urban form.

You can see the whole of Dr Ahlfeldt's lecture and many others at the Lincoln Land Institute here.

Monday, 2 July 2012

Utopia postponed - blame housing?

Owen Hatherley asks why those of us with jobs are still working so much when we have so much labour-saving technology. He doesn't get anywhere near a decent answer, and overall it's not a particularly good piece, what with the erroneous claim that the average Briton works a 12 hour day and the suggestion that all service jobs - including Owen's? - are "pointless". But it's an interesting question (go read Keynes), so here's my attempt to answer it.

Let's look at it in terms of supply and demand. More about supply later, but for the moment I think we can all accept that technology improvements have vastly increased the amount and quality of stuff we can afford. Most of us could probably work part-time and have a quality of life - certainly a life expectancy - that most of our ancestors would envy.

Yet we generally choose not to work short hours, and in part that's because we want a much better quality of life than our ancestors had. Our incomes have increased hugely in real terms, but so have our demands for goods and services. In economic terms, most of the stuff we want consists of 'normal goods', i.e. stuff we are willing to spend more on when our incomes increase. It's not clear, however, to what extent this all really makes us happier or to what extent we are just on a 'hedonic treadmill'.

But do we want more stuff for its own sake or because we want to show off to everyone else? Do we desire goods and services for their inherent consumption value or for the social status they impart? Social status is a positional good, something which we value according to rank rather than absolute quality - even if we could all have afford to have good lives, only one of us could have the best, and that seems to matter to us. It does of course help, but only a little, that we don't all share the same subjective rankings.

On the supply side, it obviously matters how the things we want are made. One important aspect is whether the production process is labour-intensive or not. Things that are easily mechanised have generally got a lot cheaper compared to our incomes over time, but things which require a lot of human labour, such as hairdressing or adult social care, have not. That's because you have to pay someone to do it and other people have high income demands just like you do.

I would suggest that the housing market combines many of these features, and may be the most important reason why we continue to work long hours. Housing demand is income-elastic: when we earn more we often spend it on bigger houses or better locations. Housing is positional in the sense of social status (one of the great things about a nice home is inviting people around to envy it entertain them) and in the sense that it is spatially fixed: each home gives us access to a different bunch of locational goods, which in some cases like access to a particularly good school may be extremely valuable. And housing production is intensive in two expensive and relatively scare factors of production: labour and land.

Certainly housing could be cheaper if we built a lot more of it, but I'm not sure whether it would be cheaper in absolute terms (i.e. we'd spend less on it) or in relative terms (i.e. we would maintain our level of spending but get more for it). Either outcome would be an improvement on what we've got now, but not necessarily in terms of fewer hours worked.

Friday, 29 June 2012

Rising cycling casualties: policy needs to catch up, and fast

We had new statistics on road casualties in 2011 at both national and London level yesterday, and in both cases the figures on cycling make for grim reading. The number of cyclists killed or seriously injured increased from 2010 levels by 15% nationally and by an even worse 22% in London. As the chart below shows, fatal or serious cycle casualties in London are down over the long term but up sharply in recent years.

Naturally people are interested in what this means for the rate of cycling casualties per trip or mile cycled. Some other DfT figures released yesterday indicate that miles cycled nationwide rose by only 2%, which implies a large increase in the casualty rate (see's number crunching). TfL will probably not release statistics on cycle trips in 2011 until their next Travel in London report (probably just after Christmas) but I don't think anyone seriously expects cycling to have grown more than 22% in a single year.

And anyway, even if I'm wrong and cycling levels were up by more than 22%, would that make such a large increase in the absolute number of casualties okay? To illustrate the point, say the number of trips cycled in London grew by 25% each year for five years and the number of cyclists killed or seriously injured by 20%. Going by TfL's figures for 2010 from this report and assuming everything else stayed the same, then by 2015 we'd have 1.5m cycling trips a day, a modal share of 6%, a lower cycling casualty rate BUT over 1,000 cyclists killed or seriously injured a year. Should that really be considered a success? 

Of course that's a slightly unrealistic scenario, but the point is that cycling casualties are rising at an alarming rate, in part because more and more people are choosing to cycle (for whatever reason). We all like to see cycling growing, but if it is not to result in truly horrific numbers of deaths and injuries then we need a complete transformation in cycling conditions in this city. 

Fortunately there is, on the face of it, a political consensus around this issue, as in the run-up to the 2012 mayoral election every major candidate endorsed the London Cycling Campaign's 'Go Dutch' manifesto, which entails dropping our current approach to road design and embracing the Dutch ethos, including high-quality segregated cycle lanes on busy main roads. So really there should be no debate about the general principle of what do do, just about the details of how to do it. I hope the forthcoming London Assembly transport committee inquiry into cycle safety adopts this approach.

Of course Transport for London and various individual politicians will say that it can't be done in London because we don't have the space on our roads. But I think these latest casualty figures show that we have no choice but to make the space. To turn the old slogan on its head, we haven't built the infrastructure but the cyclists are coming anway, and as a result they're getting killed or injured in greater and greater numbers. They have forced the issue, and policy has to catch up.

Tuesday, 19 June 2012

Homeownership and growth in the great recession

There has been a bit of a discussion going round about the link between home ownership rates and national prosperity - see Marginal Revolution, Matt Yglesias and Melbourne Urbanist.

The upshot is that when you look at the data, home ownership rates seem at best uncorrelated with prosperity at national level and possibly even negatively correlated. Lots of poor countries have very high levels of home ownership while at the other end you've got countries like Switzerland and Germany, who seem to have got by pretty well with ownership rates of less than 50%.

Part of this pattern, in Europe at least, is explained by the fact that many post-Soviet countries simply handed over ownership of public housing to the occupiers en masse as part of their economic reforms in the 1990s, instantly creating very high rates of home ownership.

But another big part of the explanation is that wealthier countries are more urbanised, and higher rates of urbanisation mean lower rates of home ownership. Big, dense cities are great wealth creation machines, and higher-density housing is more likely to be rented than owned, partly for reasons of population transience and partly for reasons of efficiency - owning an apartment is a risky business because you are so affected by your fellow building occupants, so it often makes sense to let one landlord own the whole building and absorb all those inter-apartment externalities.

Lastly, Andrew Oswald has argued that higher rates of home ownership impede the labour market by reducing mobility (because selling a house and buying another is generally more costly than moving between rented houses), thus lowering long-run economic growth. Argument still rages over this theory though.

What I think has been left out of the discussion so far (apologies if I've missed it from anyone else) is that countries with higher rates of home ownership also seem to have done worse out of the 'great recession' of the last few years. The chart below shows home ownership rates in Europe in 2009 (from Eurostat) against the change in per capita GDP between 2006 and 2011, adjusted for inflation (from the IMF). The size of the bubbles represents current GDP, also from the IMF.

The two countries on the left with lowest rates of home ownership are Switzerland and Germany, and both of them have actually seen positive per capita GDP growth in the last five years. On the far right you've got two very small countries with very high home ownership rates and very differing fortunes of late, Slovakia having posted pretty strong economic growth of 8% over the period and Estonia having lost about 9% of GDP. Of the bigger countries with home ownership rates over 70% only Norway and Belgium have grown over the period, while Italy, Spain, Portugal, Finland and the UK have all seen economic contractions. And then there's Greece down there at the bottom. Obviously this leaves out anything that has happened in 2012 so far or is about to happen, and it certainly looks at the moment as though the likes of Spain, Italy and Portugal are looking at more recession to come - possibly very deep and long ones if things go really awry.

So what should we make of this pattern? Is it just coincidence, or just the result of some other factor? It could, for example, just be that poorer countries have more home ownership (as above) and poorer countries did worse in the recession for some other reason. We would need some careful analysis to identify the real causal paths, but as far as I can see there has been zero academic work done on this so far. That's surprising, but it does at least leave a nice big gap for speculation to fill!

The key features of the great recession in most countries were/are bursting property bubbles and credit crunches. What a high rate of home ownership does is expose more households to asset price increases in the bubble phase (possibly increasing the risk of 'irrational exuberance') AND to big drops in wealth from falling house prices in the bust phase, which then lowers household spending as they try to restore their balance sheets. Meanwhile, the drop in bank lending freezes the owner occupied housing market, making it harder to move house unless the rental market can quickly expand. So you've got a combination of job losses (from the wider recession), lower consumer spending even where people haven't lost jobs, and barriers to mobility making it harder for markets to adjust.

Another way of putting it is that high rates of owner occupation make the wider economy vulnerable to falls in housing demand, because falling house prices make owners want to spend less. But in a country where most people rent, lower housing demand (e.g. through job losses) result in falling rents, which frees up money for higher spending in other areas, helping to stabilise the economy.

There may well be benefits to home ownership (e.g. owner occupiers may take better care of their homes and it may provide a more stable environment for children), and politicians tend to like it, but I think the experience of the last few years suggests there are potentially quite large downsides too.

Saturday, 16 June 2012

Despite what I said before, maybe cycling casualty rates aren't strictly comparable between Britain and the Netherlands. How about fatality rates then?

Back in April I posted an analysis of fatal and serious casualty rates for cyclists in Britain and the Netherlands, which reached the eye-catching conclusion that "just over 500 British cyclists are killed or seriously injured in collisions with motor vehicles for every billion km cycled, over eight times the rate in the Netherlands". I used data from the British Department for Transport and the Dutch road safety institute SWOV, but as a couple of commenters pointed out these do not in fact seem to use completely consistent definitions of what constitutes a 'serious' injury, so the comparison might be misleading. For example, snigbo said,
On comparing serious injuries: as discussed in DfT rrcgb2010-6.pdf, GB "serious" includes all admissions to hospitals, many of whom will have a MAIS score of 1. Table 11 suggests that 28% of hospital-admitted cyclists were MAIS 1, so reducing the GB number by that amount would be appropriate.
There is also the problem that for both countries the casualty figures are based on what is reported to police, and there may be differential rates of under-reporting, particularly for incidents not involving motor vehicles.

These are valid concerns, so I've updated that post with a health warning over the data. I'm grateful to the commenters for pointing these issues out, and I apologise if anyone was misled.

Can we then make any useful comparisons between the two countries? Well, it may be tempting fate to go back to the same data sources, but as was also pointed out the data on fatality rates should in principle be more comparable. After all, a fatality is a fatality wherever you are, and you would also expect minimal problems of under-reporting.

The problem here is that the SWOV data on contributory factors in cycling fatalities includes a large number (a majority, in fact) of cases described as 'Not matched', i.e. they don't say whether a motor vehicle was involved or not [Update: Note, this doesn't affect the total fatality rate, which is known - it's just that not every case is allocated to a particular type of incident]. You can just exclude all these unmatched cases and look only at the breakdown of the remainder, which is what I have done in the chart below. Having been burned before I would be cautious about putting too much weight on the results, mainly because of the large number of 'not matched' cases in the Netherlands data, but they do at least seem to be telling a similar story to the previous data, i.e. that the relative risk posed by motor vehicles to cyclists is higher in Britain than in the Netherlands. 

Wednesday, 25 April 2012

What we've got to learn from the Netherlands

Update: As commenters below have pointed out, the data may not be comparable enough between the two countries to draw such a strong conclusion, for reasons of definitions and possible different rates of under-reporting. See new post on the topic here.

I used data from the Dutch road safety research institute SWOV yesterday to compare cycle fatality rates in the Netherlands with those in Britain, and Mark pointed out on Twitter that SWOV data also breaks down the number of casualties according to whether or not any motor vehicles were involved. This is handy, as it allows us to see whether the low cycle casualty rate in the Netherlands is due to (a) fewer collisions with motor vehicles or (b) fewer casualties from collisions with pedestrians, other bikes or cyclists just crashing into stuff or (c) all of the above.

This table indicates that 64% of serious or fatal cycle casualties in the Netherlands are the result of collisions with motor vehicles*. This compares with 91% in Britain, from this DfT table**.

We saw yesterday that the cycle fatality rate per km is more than twice as high in Britain as in the Netherlands. According to SWOV data the gap is even larger when you include serious injuries: in Britain there are 556 cyclists killed or seriously injured for every billion kilometres cycled, compared to 96 in the Netherlands (in both cases I'm using the most recent year available, 2009 for the Netherlands and 2010 for Britain).

Put these figures together and you get the chart below, which shows that the rate of serious or fatal cycling casualties not involving motor vehicles is actually reasonably similar in the two countries, 35 per billion km in the Netherlands compared to 49 in Britain. But the gap for collisions with motor vehicles is huge: just over 500 British cyclists are killed or seriously injured in collisions with motor vehicles for every billion km cycled, over eight times the rate in the Netherlands.

I think this shows just about as starkly as possible the consequences of two different approaches to cycling: one which expects cyclists to constantly mix with heavy and/or fast-moving traffic, and one which doesn't. In the Netherlands they very carefully and deliberately try to reduce the chances of a serious collision between motor vehicles and cyclists, and you know what, it looks like it works. In Britain we don't try very hard to do that, and we get the results you see above.

* Select 'Bicycle' under 'Mode of transport' and then nest the 'Type of accident (E-code)' variable in the rows. There are a lot of blanks ('Not matched') under 'Type of accident' for fatalities, so I just calculated the percentage based on the non-blank records)

** Scroll over to 'All areas' and tot up the pedal cyclists killed or seriously injured in collisions with other cycles, pedestrians, or in single vehicle, no pedestrian accidents. The remainder are the results of collisions with motor vehicles.

Tuesday, 24 April 2012

No, cycling is not safer in Britain than in the Netherlands

Giving evidence before the Transport Committee today, Ministers Mike Penning and Norman Baker declared that Britain has nothing to learn about cycling safety from the Netherlands because our rate of cycling fatalities per head of population is lower. 

Given that both ministers immediately went on to note that many more people cycle in the Netherlands than in Britain (Mark has the quotes), it is difficult to know what to make of this*. It should be blazingly obvious that if hardly anyone cycles in Country A it is likely to have a lower rate of cyclist fatalities per head of population than Country B where nearly everyone cycles. Any Minister who claims this as evidence that cycling is safer in Britain is misleading either  parliament or themselves. Penning and Baker seem quite proud of their factoid, which implies the latter. That is worrying, and not just for cycling policy.

As many people on Twitter immediately pointed out, a reasonable measure of cycling safety would be to calculate deaths or serious injuries per mile or kilometre cycled. And in fact that's what the statisticians at the Department for Transport do. Their table RAS53001 shows trends in fatality and casualty rates per kilometre for various modes of transport. The fatality rate for cyclists in 2010 was 22 per billion kilometres, down by a third from 33 in 2001 but still some seventeen times higher than the fatality rate for those in cars

So how does this compare to the Netherlands? We are fortunate that the Dutch road safety institute SWOV publishes comprehensive statistics on road safety trends in that country here - and in English too. These figures include fatality rates for the various modes of transport, equivalent to the DfT statistics mentioned above (note, SWOV calls passenger casualties 'Victims per seat'). 

In 2009, the latest year available, the fatality rate for cyclists in the Netherlands was 9 per billion kilometres, less than half that in Britain (21 in 2009). So cycling in the Netherlands, using a sensible measure, is more than twice as safe as in Britain. The evidence of the Ministers to the Transport Committee was wrong (as if that wasn't already obvious).

The SWOV data throws up some other interesting comparisons. The fatality rate for car drivers or passengers in actually lower in Britain than in the Netherlands (in 2009, 1.6 per billion km compared to 2.1). This means that in Britain, fatality rates for those in cars are 13 times higher than for those on bikes, compared to 4.4 times in the Netherlands. The chart below compares fatality rates for cars and bikes in the two countries - again, all based on official statistics.
In summary, we have nothing to teach the Netherlands on cycling safety, and I trust the Transport Committee (and the Times, who will be reporting on the hearing) won't fall for such obvious nonsense from the two Ministers.

* It reminded me of the line in Ulysses to the effect that Ireland had the honour of being the only country to have never persecuted Jews "because she never let them in".