Thursday, May 22, 2014

How to make urban housing more affordable part 4: build more rapid transit

One of the first posts I did on this blog (or rather that I translated over from French), was a post about the the importance of speed for mode selection. In that post, I indicated how people tend to have a certain threshold for how far they want to live from job, commercial and entertainment centers, and that this distance was measured not in kilometers or miles, but in minutes. For a city, often the greatest center is the downtown area, people prefer to live within a reasonable distance from it. However, the different modes of transport have different average speeds, walking is about 5 km/h, transit (regular buses or streetcars) is about 15 km/h and cars on regular surface streets go at about 30 km/h.

The result was this image:

A basic city with only surface streets
The point here was that if someone wants to live within walking distance from the downtown area, then they would want to live in the green zone, the area that is within acceptable walking distance from downtown. If people want to live within acceptable distance by transit, they would want to live in the orange zone (or the green zone). The red zone was the area that was appropriate only for cars, so lots of parking, wide roads, low density. Outside the red zone, the area is undesirable for everyone, so developments will concentrate in the three zones, and will tend to be appropriate for the zone they're in (as long as zoning isn't too stringent, which is a condition rarely fulfilled in North America).

This is an illustration of core principles of development, as far as I see it, "development follows transport" and "the main mode of transport shapes the form of development".

The green zone's development will be a dense urban area, the orange zone will be a bit less dense but still pretty urbanized (a streetcar suburb) and the red zone would be sprawl. Note that this is only the maximum density each zone can support. You could ostensibly build car-oriented developements in all three zones, and build streetcar suburbs in the green zone too. However, building dense urban neighborhoods in the red zone is a fool's errand.

Another thing I had said was that the price of a house is actually the sum of two prices:
  • The price of the building
  • The price of the land
OK, so why am I saying this? Because those areas have a direct influence on the price of the land. Think about it, the price of the land is also about supply and demand, if 25% of people want to live in an urban setting (the green area), but only 3% of the buildable area of a city is close enough to downtown to make walking viable as a mode of transport, then that means that you will run into a shortage of green land very quickly, which will drive land prices up very fast. You can compensate with higher density to some extent, but high land prices will still be a drag on housing affordability.

So this means in short that because walking is so slow, and transit is still much slower than cars, there will always be much more land available for car-oriented development, so land prices for car-dependent developments will always be much cheaper. On the other hand, land prices in dense urban areas will always be extremely high since there's so little of it to go around. You cannot build an urban area out in the exurbs, it doesn't work that way.

So what is the solution to this?

Rapid transit

Rapid transit helps to tie together walkable areas by providing a shortcut for pedestrians and transit users to get around the city much faster as rapid transit can reach speeds of 35-40 km/h or more. Here's what the basic city portrayed above looks like once we add two subway/train lines to it:

A city with two subway lines
These rapid transit lines have multiplied by much the amount of walkable, transit-friendly areas within a reasonable distance of the downtown area. And what does that mean? That means a much higher supply of land on which dense urban developments can be built thanks to greater proximity and access to the downtown area. This higher supply means that land prices can fall for these neighborhoods, making housing more affordable for urban areas.

However, though the urban neighborhoods are made cheaper, the zones around stations are made much more expensive than they were when they were "red", for cars only. Another factor to consider is that the rapid transit lines may make the downtown area even more attractive as it spreads and concentrates more things, which may make the downtown area more expensive than before, even as urban neighborhoods are available elsewhere and become cheaper.

So building rapid transit is a great way to relieve pressure on urban housing, so long as zoning is relaxed and the construction of urban areas is allowed rather than forbidden.

It works for sprawl too: highways and sprawl

Another thing I pointed out before was that cars also have their version of rapid transit in the form of highways/motorways/expressways (choose the term you prefer). These limited access roads allow cars to travel at speed of 100 km/h and above. Congestion can reduce those speeds, but only during peak hours. These roads act like shortcuts for car movements, just like rapid transit did for walking and local transit trips. The result is a spreading red zone, very, very far from the center, centered around interchanges.

A city with two highways crossing its downtown area
The sheer size of the red zone here is awesome, here is what it looks like compared to the two previous cities:
Size comparison between the basic city (lower-right), the rapid transit city (upper-right) and the highway city (left)

So highways help do the same thing for housing affordability in car-oriented neighborhoods that rapid transit does for urban housing affordability. Highways are thus a vital element of sprawling city to preserve housing affordability. A large city without highways but still car-oriented would also become more and more expensive over time as desirable land runs out.

I feel I must point out in all honesty that, yes, it does provide an explanation why the cities that have few or no highways near their downtown, like Vancouver, Toronto and San Francisco, all are afflicted with expensive single-family housing in their suburbs. Which may be caused by the lack of high-speed roads to the city itself, which restricts the land that provides an opportunity for development.

It would mean that, yes, building an highway right through Vancouver's downtown to the suburbs could effectively make suburban single-family housing more affordable by bringing closer all the suburbs to the downtown area and making new land available for development as they would become close enough to Vancouver's downtown. No, I do not recommend it as urban highways have much worse side effects on a lot of things, like the vibrancy of the urban neighborhoods they cut in two, but I do acknowledge that it is quite possibly a way to bring house prices down.

Note also that another possibility to deal with the issue is polycentricity, essentially build new downtowns to create urban neighborhoods around them too. It is quite possible. Tokyo is the best example, it doesn't have just one downtown, but many downtowns, all existing around stations of the Yamanote line (Shinjuku, Shibuya, Ikebukuro, Tokyo, Ueno, Shinagawa). However, tying these downtowns together with rapid transit is almost a must.


When you have maxed out the available land in proximity to the downtown area for urban neighborhoods, it's time to build rapid transit links to make sure you make new lands viable for this type of development, otherwise you have a shortage of land which pushes land prices up, a price increase housing will have to absorb. Just make sure the zoning ALLOWS such development (or redevelopment) to occur. If you are in a green zone in which you can build walkable developments but zoning imposes "red"-style sprawl developments thanks to density caps through minimum lot sizes, height limits, parking minimum, etc... then it doesn't matter that the zone is ostensibly walkable, it is still "red" for legal reasons.


  1. You avoided saying it explicitly because I know you know it: rapid transit raises the price of land to make it less affordable than before.

    Low land prices should not be a policy goal.

    Productive places and a resilient growth pattern should be the policy goal. If land prices rise, then a) you can afford to cut the % taxes, leaving more money with people to cycle around the economy, innovate, travel, create, improve wellbeing etc.; and b) it's a signal to seed a new complete neighbourhood with its centre at least 10 minutes' walk from the next nearest one.

    The absolute value of land prices is irrelevant. The relative value of land prices to median salaries is very important, and the latter ratio is improved by a) seeding new complete neighborhoods that will be smaller and so have lower land values BUT that follow a resilient growth pattern (a town square, intersection density, use mix, walkable streets, parks, trees etc.) and b) allowing lots and lots of opportunity for money to cycle around the economy, which is also a function of street design (short lots, no parking minima etc.) but also light regulations, like hiring and firing, and food trucks.

    1. Actually, I did mention that building rapid transit does increase the value of the land nearby in comparison to the prior situation, however, the price of the land is still much below the value of the land downtown and allows for price relief on existing urban areas in the region. Another factor I also mentioned is that rapid transit can make the downtown area more attractive, so these two effects exist side-by-side.

  2. Those are some pretty beautiful diagrams!

    1. I should point out that the more auto-oriented they get, the more fascist they look…