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.]

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.

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.

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.

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.

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 road.cc'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.

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.

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. 

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.