Monday 1 February 2010

The effect of population density on cycling

Much is sometimes made of the requirement for cities to have a high population density in order to encourage cycling. It is said that it is essential for populations to live in densely packed areas to keep journey distances short before people will take to cycling.

Looking at the behaviour of the Dutch, who cycle more than the people of any other country, this seems to be a flawed suggestion. Or at least an over-simplification.

It is true that the population density of the Netherlands as a whole is quite high. There are nearly 400 people per square km in this country. Much higher than the 32 per square km that you find in the USA. However, whole country size scales don't really have much to do with the journeys that most people make on a daily basis.

Let's try this with densities of provinces or states, and cities within them. Assen is the capital of the province of Drenthe. This province has the lowest population density in the country, with 183 people per square kilometre. The capital of Drenthe is Assen, which has an area of 83 square km and 784 people per square km.

Five US states are denser in population than Drenthe. New Jersey, Rhode Island, Massachusetts, Connecticut and Maryland all have higher densities, New Jersey's population density is higher than that of the Netherlands as a whole. Delaware has the closest density to Drenthe, at 170 per square km. The capital of Delaware is a small city called Dover home of just 35000 people spread across 58 square km - which makes 617 people per square km.

These figures are really not so different to those for Assen. Assen's population makes 41% of all journeys by bike. Does anyone know the cycling rate of Dover ? Would it be reasonable to assume it's somewhat lower than Assen ?

Los Angeles in the 1950s
Or look at the bigger cities. Los Angeles has over 3000 people per square km, but just 0.9% of commutes are by bike. New York has over 10000 people per square km. That's more than twice the population density of Amsterdam, but while 38% of all journeys in Amsterdam are by bike, only 0.6% of commutes are by bike in New York (which amazingly is still enough to be in sixth place amongst large American cities).

The same is also true of Devon in Delaware. Take a look at high school parking in Delaware and compare it with high school parking in Assen. Would it be conceivable for an American school to hold a triathlon as my daughter's school did here in Assen, telling the students to ride their bikes unaccompanied to a swimming pool at a sports centre 20 km away ?

It's quite mind-boggling just how little Americans cycle. However, it's also quite obvious why. Infrastructure has been designed over decades in such a way that it excludes cyclists. The photo was taken in the 1950s in Los Angeles.

Does where you live look like an inviting place to cycle ? Driving is the norm in many places because the infrastructure is designed around the car and it makes driving appear to be the only reasonable option. You see cars and car centric infrastructure almost anywhere that you randomly drop the Google Street View man in the USA. Whereas you've a good chance of getting cycling infrastructure and cyclists in street view scenes in the Netherlands.

It's perhaps interesting to note that the highest cycling rates in much of the Netherlands are actually in the North of the country, in the least densely populated areas, where journey lengths are often a bit longer. It's not population density which really makes the difference in cycling rates, but infrastructure which makes cycling into an obvious option. It has to be the most convenient, pleasant and safe way to get about. That's why 93% of the Dutch population ride a bike at least once a week.

There are many other excuses for why populations of other countries don't cycle.

I featured that photo at the top before. It's what Los Angeles already looked like in the 1950s. Roads like this are a large part of why people would choose not to cycle.


townmouse said...

Having moved from London to the country, I've found that while the cycling around here is much more pleasant than in London (our empty rural roads are probably about as wide as the average Dutch cycle path, and even the boy racers have to slow down - although the hills take some getting used to) there are fewer people cycling to get somewhere, and more people cycling as recreation. The problem is that the shortest 'useful' journey I can make by bike is 5.5 miles (to the nearest shop) - fine if you've got the time to do it and great fun, but not really the fastest or most convenient way. Whereas in London the bike really was faster - but then public transport was also available and convenient (which I suspect explains why LA beats NY for commuting rates). Not quite sure what my point is, except to say that at a certain level of population (non)density no amount of infrastructure will make cycling more convenient. That said, if more people cycled instead of using their cars, we might have more villages with shops and then the balance would tip back in favour of the bike. No doubt you're about to tell me the Dutch have managed to retain their local shops as well as everything else, and I'm just going to have to break down and emigrate...

David Hembrow said...

Townmouse: 5.5 miles is not an unusual distance for Dutch people to cycle. The figures show that 35% of all journeys in the country up to 7.5 km are by bike. Also, 12% of journeys between 7.5 km and 15 km are by bike.

It's very normal for Dutch school-children to make journeys of that sort of length, unaccompanied by adults. I see plenty of them each morning as my commute is in the opposite direction to what is shown in that video. Even when it's -10 C and completely dark first thing in the morning, there are lots of children making that journey.

Of course, it's not just children. There are plenty of adults too. Infrastructure makes all the difference. It changes what could be an unpleasant ride amongst motor vehicles into a problem free ride (as shown).

Much of the growth here now is in longer cycle journeys, 10 km and over. This is the reason why longer "cycling superhighways" which offer direct routes not only into cities, but on the longer distances between them, are being pushed now. I've a blog post about this coming up in a few days.

Villages here do quite well for shops compared with those in the UK. We could get everything we need on a normal basis from the shops in any of the local villages (except a few of the really small villages).

2whls3spds said...

I live in a much less densely populated area ~180 people per square mile which I believe converts to around 72 people per square kilometre. Infrastructure does not exist, there are 3 good sized schools on the single main road about 1.5 miles from me, there are NO sidewalks, no cycle lanes, no shoulders and the road has a posted speed limit of 45mph but cars quite often run 60mph on it. Small wonder we don't walk and ride more.

There have been several efforts made to reduce the speed limit to 35mph in the area near the schools but it has met with resistance, mustn't slow the motorists down you know they are sooooo important and believe they own the roads because they own a vehicle and have a "right" to drive!

New York is much more of a pedestrian/mass transit type of city. We go there on occasion by train, then walk or use the subway to get around. A bicycle isn't really necessary.


David J said...

Build it and they will come!
I recall when petrol prices went up a couple of years ago, so many more people started riding and we heard a lot of complaints back then about the lack of safe cycling routs... I suppose the new cyclists were dismayed by lack of infrastructure.
I wonder how many of them returned to their cars after the prices stabilized... and how many might have continued cycling if our city had done their bit to improve road safety?

Brent said...

Density is one of those sorts of arguments that can be used for and against cycling. My hometown of Los Angeles often argues, in effect, "We're too densely populated to add cycling infrastructure." By contrast, other cities might say, "We don't have the population density to justify spending on cycling."

When an argument can be used on both sides of an issue, I find it suspect.

J.. said...


The problem is not that the density argument can be used both sides of the issue. In fact, it can't be used on either side. Both those arguments are total BS. LA has lots of space and very wide streets that would very easily accommodate bicycle paths. And its overall density is more than enough to make it worth the trouble.

David Hembrow said...

Brent and J..: You're both saying the same thing and I agree with both of you.

Anonymous said...

There are things associated with density in the US that I think you are missing and that is what is causing you to misunderstand why people in the US are pushing to increase density in the US.

This is a walk score map for Atlanta. What the program measures is how many goods and services there are in walking distance from a given address.

Why this matters for bike usage is that most bike trips even in the Netherlands are less than 3 miles. So the more things that you have within 3 miles, the more opportunity you have for people to bike somewhere instead of driving.

In the US, the places that are the greenest on this map are also the most likely to use bikes. They also were likely to be built before WW2, and not provide a lot of free parking.

If you look at the places in red on this map, they are the most car dependent. In these neighborhoods housing is strictly separated from retail and work. As the crow flies, you might have shops and businesses within three miles of your residence, but because of the way the streets are laid out in cul-de-sacs, its tough to walk to them or to bus routes. The density in these neighborhoods are so low that if they are served by transit at all it might just be just once an hour or less or just at rush hour.

Part of the reason people in the US drive everywhere is that the huge parking lots make walking, biking or transit somewhat impractical. When advocates in the US are pushing for increasing density what they mean is that they want to have neighborhoods with much smaller parking lots. They are trying to get rid of mandatory minimum parking requirements, that lead to sprawl and lots of free parking.

Remember gasoline is much cheaper in the US, car registration is much cheaper in the US. Incomes are higher and the cost of driving is less so people use autos a lot more.

Environmentally this is bad for the planet. But the thing that drives transit usage (and just alternatives to cars) in the US is expensive parking. In the places like Manhattan where parking is expensive, people will take transit.

Pushing for increasing density is a way of pushing for more expensive parking and that is associated with a lot of positive benefits in the US.

In Europe the housing stock is different. After WW2, it was rebuilding and so it was just a lot poorer. Widespread auto usage didn't really hit until the 70's and even then higher gas taxes and tighter land regulation discouraged sprawl.

David Hembrow said...

Anonymous: Thank you for your considered response. I do see the point that is made by the attempts to increase density in the US, but distances which people will walk are a lot shorter than those which people will cycle.

Looking at the map at the walkscore website that you point to, almost the entire city of Atlanta is within 3 miles of a green "walkable" area. This is a very short distance for cycling

The same is true of Devon in Delaware, which I used as an example. It's a smaller city than Assen where we live. The maximum distance you can travel within it is smaller. However, people don't cycle there to any great extent.

Cul-de-sacs as you refer to are pretty much unknown here. Where they exist there are short cuts for cyclists and pedestrians. The woonerf is in essence the Dutch take on the culdesac. They exist in the UK, but the UK was influenced more by US design. This was noted by Steve Melia a while back.

These days you will find few countries with higher car usage than the UK. This is despite the cost of petrol being very similar between the UK and the Netherlands. Dutch car ownership was once higher, but British car ownership overtook the Netherlands, despite British people being less able to afford cars. The reason is simple. Getting about without a car in the UK is unpleasant.

I've been to the US. Only a small part of it, admittedly. However, I know how difficult it is to travel by foot or by bike. I recall attempting to go to the pub with some colleagues once. There was no sidewalk to use for our short journey, so we had a choice of walking on the busy road or of walking on the grass lots outside company buildings, which had sprinklers running to water the grass. Police cars slowed down so they could see what we were doing. We only did this once.

You seriously underestimate the distances that people will cycle if the conditions are good enough. In the Netherlands, 34% of all journeys up to 7.5 km and 15% of those between 7.5 km and 15 km are by bike. 3% of journeys over 15 km are also by bike. The US isn't achieving a cycling rate even for short journeys that the Netherlands has for long ones.

In the USA, 40% of journeys are under 2 miles, yet 90% of those trips are by car.

MiddleAgeCyclist said...

Hi David

You know I follow your blog, agree the cycling infrastructure in Holland is second to none and only improved facilities will make cycling more attractive in other places (the UK for one). With that in mind I must direct you to this website which purports to show an atrocious cycle lane allegedly in a Dutch town called Volendam.

It made me chuckle! Any comments?

David Hembrow said...

Hi Darrell, It's a very amusing picture. However, does it look real to you ? Perhaps someone painted this somewhere as a prank. Perhaps the supernaturally bright white of the bicycle symbol indicates an altered photo. What I'm sure it isn't is a cycle path which meets any standards in this country.

Volendam has now been comprehensively photographed by the Google Street View car, so take a look and see if you can find it.

J.. said...

When it comes to density in American cities, there's a lot more to it than just parking lots. All the zoning codes and building ordinances proscribe socalled urban sprawl. You're not even allowed to build higher density cities, even if you wanted to.

There's a relatively new movement in the US called "new urbanism", which is trying to change this. There's an excellent presentation by one of its leading proponents, Andres Duany. You can find it as a multipart video on Youtube. This is the first part:

It's not exactly about cycling, but I highly recommend it to anyone who's interested in how to (and how not to) build cities.
It also shows that there already is strong demand for higher density living and walkable towns.

J.. said...

Found the place in Volendam. Obviously a prank...,5.509644&sspn=3.266348,6.976318&ie=UTF8&hq=&hnear=Volendam,+Noord-Holland&ll=52.494157,5.075356&spn=0.001558,0.004018&t=h&z=18&layer=c&cbll=52.494101,5.075252&panoid=NqEqhfjJrFkBt8N394WBeQ&cbp=12,49.9,,0,-2.5

MiddleAgeCyclist said...

I cannot believe it is real either. I feel the website has been taken in by giving this "facility" the monthly award. Made me laugh though.

Kevin Love said...

Since you asked...

Bicycle commute mode share in the USA's State of Delaware is 0.4%.


From the same document I see that the US state with the highest walk/bike commute mode share is Alaska. So much for the density argument.

J.. said...

I think Alaska may be a good example. Density may be low, but urban density, compactness of town and cities, is probably much higher then in the lower 48. Resources and building materials are more scarce and the remoteness and climate make construction and maintenance both more difficult and more expensive.
All infrastructure is more expensive, because most of it has to be shipped in. So it makes sense to use as little of it as possible, resulting in quite compact, walkable communities.

I've never been to Alaska, so I can't speak with any authority, but it seems obvious to me.

Anonymous said...


the url you gave, is so good. I can recommend it to anyone.

Marco te Br├Âmmelstroet said...

Dear David,

Used (and adapted) some of your "excuse arguments". Hopefully to your likings:

Anonymous said...


As the crow flies, individuals might be within three miles of walkable area. But effective distances in the post WW2 US suburbs aren't as the crow flies.

In the US in the post WW2 era, land uses were strictly separated. Housing got bunched into residential neighborhoods filled with loop to loop streets and cul-de-sacs and traffic was shunted off to high traffic, fairly high speed thorough fares with car speeds of 40 to 45 mph (64 to 72) kmph [often with 4 to 8 traffic lanes]. In terms of perceived safety, individuals don't feel safe on bikes next to traffic moving that quickly.

Retail,went to malls and mini-malls on these thorough fares because retail liked the traffic and didn't care so much about the noise.

Office and industrial uses were segregated further because the argument at the time was that families wouldn't want to be next to noisy or polluting factories.

In the Netherlands, to build the bike paths they reclaimed traffic lanes for bike paths. That had two purposes, it increased percieved safety, but more important it slowed down traffic that resulted in increases in actual safety. But the overall built environment is also much more mixed use.

But politically what is preventing that from happening in the US when traffic lanes are reclaimed from traffic, the thorough fares are still so wide it doesn't get car speeds below 25 mph (40 kmph) where people start feeling more comfortable riding near cars.

No one feels safe walking across the street, no feels safe riding there bike across the street when traffic is moving so quickly.

The push in the US for density and grids is that grids are a type of traffic calming that slows down traffic, but is still permeable to bikes and pedestrians. They also diffuse shopping away from being bunched up tightly in mini-malls and malls on big thoroughfares (where pedestrians and bicyclists fear to be) and spread it thorough out the neighborhood. (increases the walkscore)

More importantly, as you build denser and with more mixed uses, you create markets that have plenty of retail, employers and etc with-in three miles.

Remember the push for creating lots of trips of less than 3 miles came from research done by the Fiets Beraad (see table 4.4 on pg 19 here) Bike use for trips drops off substantially after 5 km.

In general most of the Europe is already built like the pre-WW2 neighborhoods in the US. The Atlanta and Barcelona regions contain about the same number of people, Altanta averages about 6 people per hectare and Barcelona averages 171 people per hectare. In Barcelona, people regularly use transit, bike and walk. Its too dense to drive everywhere, parking is expensive. In Altanta, generally things are so spread out, cars are your best option to cover the vast distances between home, work and shopping. Free parking is everywhere.

When advocates in the US are pushing for increasing density, they are arguing that the US shouldn't be building more regions like Atlanta, Phoenix, and Las Vegas where urban areas spread for hundreds of miles across. They want US cities to start building up, not out. But these messages aren't really directed at the Netherlands. There isn't a sense that the Netherlands needs to turn into Manhattan.

David Hembrow said...

Anonymous: We're "singing from the same hymnsheet". I do understand what you mean about the cul-de-sacs and lack of permeability by bike and on foot. Britain has produced exactly the same kind of development, and continues to do so. Apart from making journeys longer, these also open onto busy roads, reducing subjective safety, and lack facilities. On the other hand, it's been a pleasure here to watch a new housing estate being built, complete with temporary local supermarket, hairdressers, snack-bar and schools all in temporary buildings from the very start, and linked to the city centre by a bicycle route which is absolutely as direct as possible. This is how it should be - everywhere.

However, having said all that, that places such as Dover still have such very low cycle usage despite their overall size being such that all journeys have to be short shows that the conditions on the streets are really more important than the distances - at least to the point that the distances become prohibitive.

Neil said...

I don't understand the love of the grid system. To my mind, grids are really horrible and benefit cars too much, and at the cost of pleasantness.

I can see that complete cul-de-sacs are a problem, but that sort of approach coupled with cut throughs for peds/cycles is surely the most pleasant?

David Hembrow said...

Neil, I agree with you. Cyclists need an advantage - and that's exactly what we see here. There is a grid for cyclists, providing more direct routes if you cycle, but drivers tend to have to go "around the houses" to get where they want to go, and wait for more traffic lights and so on than cyclists do.

I was recently surprised to find that driving a van between a customer's house in the village of Rolde a few km East of Assen and our home in Assen I passed through no fewer than seven sets of traffic lights. That's six more sets than making the same journey by bike using my usual route - though I can also do it with none.

J.. said...

I disagree,

Grids are fine as long as they're shared use and low speed. Grids only get cumbersome to cyclists when it's all tarmac 4-laners. A well-designed grid with priority through-ways and low speed residential streets is probably more effective than cul-de-sacs because it shortens the average trip and distributes traffic more evenly. A grid has much greater capacity for traffic in general. Only the high-speed grid is an impediment to walking/cycling, but the whole idea of a grid is that you don't need these high-speed, high capacity tarmac barriers.

Grids Good, cul-de-sacs Bad!!

See my earlier link for further detailes:

john bailo said...

I grew up in Queens New York and did a lot of cycling in the 1970s during my teens. I remember that it was easy to cycle then for a couple of reasons. First, there was (and maybe still is) a Greenbelt that ran from Flushing Meadows Park east across Long Island through Cunningham and other parks all the way through Nassau County. It was fantastic! An idle in the middle of the city.

But also another reason: during the day there weren't any cars on the road -- Dads were at work!

That's right, the biggest change especially in America is the 24 x 7 lifestyle that puts both parents in a family on the road all day long.

Now I live in Kent, Washington (State). This should (in theory) be an idyllic suburb to bike in, and it does have some fantastic bike trails; however, the roadways even in the country parts are packed with cars night and day! It's impossible to have a pleasant ride -- at best the ones who survive are the hardcore, ride downhill in 50 mph traffic bike-bums who are willing to take their lives in their hands!