Tuesday, April 29, 2014

The "narrow" street: narrow for whom?

I've spoken a bit about street width and street user separation before. About how I went to Japan and became a big fan of their narrow streets.  Click here for the article.

Though my theory on mixing users may not be widespread in urbanist circles, the idea that "narrow streets" are a very good idea is very popular. The point is to make a street where traffic is slower and disturbs less the area, residents as well as pedestrians and cyclists.

First of all, I would like to point out that the term "narrow street" is a misnomer. This...

Residential street in Nikko
... is not a narrow street.

What is it then? It's an human-sized street. In fact, for pedestrians, the street is comfortably wide. In most North American cities, pedestrians have to make do with 1,2-meter (4-foot) sidewalks, so having a 4,5 or 5-meter wide street where they can walk feels pretty wide. Two groups of two people walking side-by-side can walk past each other with still a comfortable space between them.

But that's because an human being is about half a meter wide, a car on the other hand is on average 1,8-meter wide. Compacts are a bit narrower and SUVs are larger.  So when we call streets like that one in Nikko a "narrow" street, we still judge the street from the point of view of car drivers, not of pedestrians. So I think we ought to find a better name for them: a right-sized street, or an human-scale street, or some other term.

A 5-meter street, narrow for cars, but wide for pedestrians

How wide should streets be anyway?

That's a crucial question, and there are certain studies on the question. The problem is, the people who made the tests were engineers (BTW, I am one), and engineers don't like to make tests on a single variable in a complex environment, there's too much noise, too many factors to take into consideration. So the main studies on what lane width was the safest, they went to test this question on the simplest environment they could find... rural highways. All rural highways are pretty much the same, great visibility, not a lot of objects around the road, generally pretty straight, almost only cars on them, etc... So they tested this and concluded that the safest lane width was about 3,5 or 3,6 meters (12 feet).

But that results stands only for the environment that was tested, a nuance mainly lost on the thousands of city planners who then took this 3,5-meter width recommendation as gospel and applied it everywhere. Except that is absolutely insane. What is appropriate for highways, which are through streets made for high speeds and high capacity, isn't necessarily true everywhere. In fact, the 3,5-meter lane was made to allow cars to move quickly and safely by reducing friction between vehicles, providing just enough buffer. In residential areas, allowing cars to move quickly without friction means speeding, which mean noise, danger and depriving residents of the use of the street except in motorized vehicles.

This mentality yields absurdities like this:
This new residential street is 14 meters wide (46 feet)!
As seen from the sky
Overall, 25% of this area is just the streets. And those are streets with one lane per direction only. This is insanely wide for what it is.

How wide should streets be?

It depends on what the street will be used for. A residential street with low traffic must be narrow, because friction between vehicles is desired, not something to be feared. As cars are about 2,1 meters wide at most (7 feet), 5 meters for two lanes, one in each direction, should be quite sufficient. Cars can still pass each other, but there won't be a lot of superfluous space, forcing them to slow down to do so. You don't need to build shoulders either, as it's fine if a car stops and blocks one "lane", as other cars can go around it. What is important though is not to paint a center line, because then drivers often prioritize following the line over being careful around other street users.

What about one-way streets? I think they should be avoided. The fact that car drivers know they won't face a car coming in the other direction reduces the friction of their movement and puts them at ease to drive faster.

On-street parking might justify making wider roads. HOWEVER, this should depend on how much on-street parking is actually expected. If there are a lot of off-street parking in the area so that on-street parking is rare, you don't even need to make the road any larger. Parked cars will be rare and there is little traffic, so you don't need to provide more space, people will learn to make do with the rare parked car or vehicle coming from the other direction.

If on-street parking is likely to be used a lot, then you need to give maybe 2,1 to 2,5 meters to shoulders for parking space. Which unfortunately makes the street much wider, 9 to 10 meters. It's fine when there are cars parked there... but what about the day when most cars are gone, don't we have an enormously wide street with little friction to slow cars down? Yes. And that is a major problem...

Wide street with parked cars, narrow travel lanes, a lot of friction
The same street when there are few parked cars, the road is opened up, much less friction
The solution is to build in bottlenecks at regular intervals in the road, ideally with trees on them, a bit like so:
Modified street with parked cars, note the neckdowns with trees
Even with few cars, the neckdowns act like bottlenecks, reducing the travel lanes and creating friction
Yes, you lose a few parking spots, and you make it a bit harder to remove snow in winter, but I think it's worth it. The Dutch seem to like such streets, even if most of them are one-way only.

Street in Amsterdam, note the alternating tree/parking spot on the left
For the record, the street I used to live on in my suburban hometown was like this:
My "home street"
It was about 7,5 meters wide, and there used to be some cars parked on the street, but just a few. It was largely fine, few cars went fast on the street, even if in the case two cars were parked on either side of the street, there would be space for just one car between them. And in winter, the approximate snow removal of the city meant that the width of the street was even less than shown here.

Home street in winter
I never was scared of going walking on this street.

However, on arterials, you need to provide at least 3 meters of width per lane (10 feet), maybe a bit more if you have buses running on those routes, as the average bus is 2,6 meters wide, so they require more space to get around. But don't offer the full 3,5 meters of highway lanes.

I know, this is boring

I prefer talking of pedestrian areas and traditional streets too, but cars are here to stay for the foreseeable future. It's important to know how much space we should give them. Make no mistake, cars, the space they require and the parking they need are probably the single greatest technical obstacle to good urban design we have currently (and zoning is the greatest political obstacle). But that just means we have to think harder about how to deal with them.

Zoning's self-defense mechanism: when local democracy is local tyranny

I already described, through an example, how typical North American zoning works in a previous post (click to read it if you haven't). Now, people may wonder "if it's so bad, why is it so enduring?". I have an explanation for that.

These typical practices don't only segregate uses, they also dictate what kind of housing can be built and where, how big they can be, how big the lots must be, how far apart buildings must be from the limits of the lot, etc... Essentially, this zoning imposes certain types of housing in certain neighborhoods. The most evident impact this has is quite simply socio-economic segregation. Yes, it does deserve to be in bold.

For instance, take a neighborhood zoned for single-family houses, so one unit per lot. The lot is a minimum of 500 square meters (around 5 000 square feet), the house must be at least 100 square meters big (1 000 square feet). If land is priced at 200$ per square meter and building the house costs 1 500$ per square meter (which seems to be realistic from what I've seen in suburbs), it means that buying the lot will cost 100 000$ and building the smallest house possible will cost 150 000$. For a total of 250 000$, minimum. So everyone who cannot afford a 250 000$ house cannot afford to live in the area. 

Meanwhile, there are some limits also on how big a house can be, if a zone is split in 500-square-meter-lots and merging lots is not allowed, then the very rich who want bigger lots or very big homes will also be pushed out of the area, as they are not allowed to have these homes.

The result is segregation by socio-economic class, the proxy through which zoning was used to segregate races in the United States. Each neighborhood will not only tend to have people of similar wealth levels, which has always been the case in history, but it will only offer housing to certain classes of people and exclude legally a lot of people by making housing unaffordable to them.

For instance, imagine a city zoned so that housing in different neighborhoods are between these prices:
Example of zoning and the prices of the housing they allow
So you have a large swath of the city that will be middle-class only, with the rich in one corner and the poor all put in another. The houses in the blue area will generally not be good enough for the taste of the rich, but over what the poor can afford.

Certain cities can zone to promote some kind of mixity by having zones of different income levels close to each other, but each of these zones is still segregated.

But the segregation doesn't stop there. Since you can't build condos in single-family home areas and vice versa, it means that, for instance, single young professionals don't find housing that suits their needs in the middle-class area. So you have singles zoned with singles, poor with the poor, rich families with rich families, etc, etc...

Segregation leads to uniformity. And uniformity leads to fear what is different and most of all, change. So zoned cities like these are small enclaves of homogeneous communities, maintained by a careful segregation of housing types and prices.

But what about attempts to reform this?

Self-defense mechanism of zoning

Any attempt to change this segregation in a zoned city must take the form of a change in zoning. And in the vast majority of cities, any attempts to change zoning is submitted through a careful process including local democracy. Local residents have input on whether or not the zoning change goes through. That might seem like a good idea: give the community some control on their development. However, in practice this works much less well than in theory.

When there's a new project, people tend to ask two questions that will determine their general outlook:
1- Will I benefit?
2- Will it harm me?

Depending on their answers to the two questions, a population will be grouped in more or less 4 different categories:
Simplified decision chart for support/opposition to projects
Supporters and opponents are self-explanatory. The undecided are people who see advantages and disadvantages to the project, and can't decide if the benefits outweigh the costs. The uninterested are just that, they don't see how the project involves them in any way, so they will steer clear and not participate in the debates or votes, if it comes to that. 

Yes, in reality it's a bit more complicated than that, some people support or oppose projects for ideological and/or altruistic reasons. But largely, people tend to favor their own interests first.

The first major problem here is that most projects that require zoning changes are actually private projects, projects that aim to satisfy the needs of a few people. All housing are private projects, even public housing, because their benefits concern only a few people (directly). Not only that, but housing that needs zoning changes to be built is probably the type of housing that current residents don't want to live in (currently).

For example, introducing low-rise condos in single-family homes. Most of the families currently in the area are not likely to be interested in the low-rise condos, especially if they're the smaller kind for young professionals. And the people who would be interested in them don't currently live in the area because... well... there is no housing that fits their needs currently in the area as it's illegal to build it.

In short, what it means if that the vast majority of people will say NO to the first question. The people who would be the main beneficiaries of the change do not actually reside there, and so do not get a voice in the debate. If you look at the chart, it largely means that people will split in only two groups: the OPPONENTS and the... UNINTERESTED.

So when you have town halls, what voice will you hear? Those opposed. The local councilors will receive letters and phone calls from whom? Those opposed. If there is a vote, who will turn out to vote? Those opposed. In all cases, the uninterested won't bother, they feel like they have no skin in the game.

But still, their preference, I think, deserves to be acknowledged, the uninterested actually say "I don't care" or "do whatever you want". I think personally that's a form of support for the change, just a tacit one.

But no matter, the opposed, who in general are a minority,  just a vocal one, are the only ones involved in the debate. And it doesn't take a lot to get some people opposed and to perceive harm from any given project. In Québec City, there has been a project to build a mixed-use project on an old gas station's lot.
The lot

The project
It's already a mixed-use area with a lot of multifamily apartments, so shouldn't be a problem, right? Wrong, the project committed a capital sin, it had 6 stories when the local zoning said 4 maximum. So you had protests and organized opposition to the project. 

It didn't matter that its only difference with the rest of the neighborhood was that it had 2 stories more and that it had a more modern look to it. It didn't matter either that 250 meters to the east, there are these buildings that seem to disturb no one:
250 meters to the east: 14-story tower to the left, 7-story building to the right
The opposition managed to get a local referendum going, and the zoning change that would have allowed the project was rejected by 77% of voters!... out of the 39% who actually voted... out of the couple of blocks that had the right to vote. So about 30% of opponents, 10% of supporters... and a good 60% of people who didn't care either way Overall, 266 people voted against. To my mind, the "don't care either way" should have won and the zoning change let through, but I don't get to make the rules, to everyone's chagrin I'm sure.

This demonstrates how little it takes for some people to feel that their quality of life is threatened. And these people were passionate about this! Like the fact that the building had two stories would have given them cancer!

This is classical NIMBY-ism, opposition to any change, even the slightest one.

The result: when local democracy is local tyranny of a vocal minority

So let's sum up all these factors:

1- Zoning creates homogeneous neighborhoods where people learn to be afraid of difference and change
2- To satisfy the housing needs of people who don't have the housing they want and can afford, you need to change the zoning
3- Since changing the zoning to introduce new types of housing benefits non-residents and they don't have a voice in the discussion following local democracy rules, the project often has little to no local supporters who can participate in the debate.
4- Since local residents don't benefit directly from the project, they split up between an opponent group and a disinterested group.
5- Much of the opposition is actually quite irrational and reinforced by a fear of difference coming from the segregated homogeneous neighborhoods imposed by zoning.
6- The only local voices in the debate will tend to be opposed to the project, the supporters are not current residents and can't participate, even if the opponents are a minority, since the majority are not in support but uninterested, they win by default...
7- Hence, the game is biased to block any type of zoning change (unless people are poor and lack influence and rich developers want the zoning change)

The result is a well-oiled system that successfully blocks zoning changes to densify a lot of areas. Though the change may be largely desired, it is almost always locally opposed and proponents of these changes have to exert a lot of pressure on local politicians to surmount this local opposition, which often leads to corruption attempts.

Alternatively, project leaders may try to buy off local residents by offering them goodies, like building parks or plazas in exchange for being allowed to build what they want. Though some may be attracted by the idea, in reality it means nothing less that a public good is being funded from the pockets of the residents of just one project, which means all new housing will be unaffordable as the cost of building these public improvements that all benefit from is borne by those who buy in to the project. Which is all utterly insane.

The solution

Disarm the NIMBYs, make differentiating between residential types illegal at a regional or national level. 

Yes, I know, it's the nuclear option because it deprives "local democracy" of power. But with all I've explained, can we really talk of democracy? I think not. It's just local tyranny being built up to protect the status quo. I'm still in favor of local democracy if people actually PROPOSE something instead of opposing. For instance, if people want to turn a vacant lot into a park, let them organize a drive to propose this, including a contribution asked of local residents to fund the initiative. In other words, positive local democracy, not negative local democracy that's all about blocking any and all projects.

Friday, April 25, 2014

Fear of heights 2: the urbanist edition

I talked earlier about how some people in general were afraid of high-rises, or even just of taller buildings overall. A lot of these people take a NIMBY attitude to height, and to density overall. I also talked about how Euclidian zoning was built to impose certain housing types by making it impossible to build anything else without a zoning change.

But the truth is that NIMBYs aren't the only ones backing height limits, or strict zoning regarding housing types. The fact is that a lot of urbanists embrace the exact same thing, just with some differences.

An urbanist rationale for height limits and zoning: the human scale


Many urbanists have preferences for how cities should look like, but unlike the NIMBYs, they can explain why they have them. In general, the main key word here is the "human scale". Essentially, they want cities to be built to scale to human beings instead of to cars. An average human being is perhaps 1,60 meter tall and walks at 5 km/h, so they require proximity. A car is nearly 2-meter wide and 4-meter long, can go at 100 km/h and more and is hard to maneuver, so it requires a lot of space.

So, what does human scale mean?

It means that you build things in proximity to each other so people can easily walk from one place to another:
Street from the Vieux-Québec
Since people walk slowly and are near to buildings all the time, they can spot small details and so you need to give attention to them rather than attention to the general form of buildings:
Decorated windows in the Vieux-Québec with cobblestone street
Front window of a Japanese restaurant, with reproductions of the meals on the menu
In commercial areas, the signs advertising the shops will be small and low, near the shops themselves.
Street in Québec, note the small signs above each store on the left
On the other hand,car scale is all about wide roads with buildings spread far apart to allow cars to maneuver between them with ease:

About huge parking lots:
And huge store signs that are very far from the stores, but next to the street to allow cars to see what they advertise:
Meanwhile the buildings will be very bland with no attention to detail. Why? Because by the time people are close enough to see those details, they have already made the decision to go in and are on the way in anyway. On the other hand, the general form of buildings may be important for aesthetic purposes, especially tall buildings, since visibility will be so great that people will regularly be able to see them entirely.

Empire State plaza in Albany
The urbanists want to use the design of cities to foster communities, to create places where people can mingle and enjoy. So they explore ways to do just that, study the notion of psychological enclosure (we don't like open spaces much, we tend to feel more comfortable in forests or in cities where we feel buildings and trees enclose us), the notion of distances that allow human interactions (if we are too far away, we struggle to recognize people and it's hard to communicate verbally and non-verbally), etc...

That's all fine and good. Their explanations make a lot of sense, however, the problem is when these explanations are converted into building and zoning rules. Some of them likely make sense, and I'd support them... but it still raises a crucial question:

Where is the line between making rules to avoid bad design that deprives people of choice and making rules that essentially impose one's personal preferences on others?

For instance, because of the distance limit for human interactions, some urbanists favor only low-rise developments, 3 or 4 stories, maybe 5, with balconies for every apartment. But some have pushed it farther, they argue to outright ban buildings bigger than 4 or 5 stories, mentioning how taller buildings break the human scale. It may take the form of urbanists defending the height limits of Washington DC, trying to keep heights low in San Francisco or capping stories at 4 in the Plateau-Mont-Royal borough in Montréal, despite all these places being renowned for pro-urbanist thought.

Now, it is certainly true that apartments above 5 stories are isolated from the street below. But is it really so bad that we should ban them? Some people are social and like frequent interactions, other people are more introverted and like to be alone. For these people, the distance with the street in their apartments may well be something they seek, just like some people like to live in culs-de-sac. 

The way I see it, blanket height limits are not about good design, but about imposing one's preference on others, about making the isolated apartment high up illegal. I'd understand setting rules to avoid permanent shadows on the street, like by asking higher floor be set back from the street further or only allowed on larger streets. That way, the first 3 or 4 floors can be the low-rise buildings that favor life on the street, and the floors above that can be a little set back, not disturbing people on the street, even if they don't add to it.

We all know the "tower in the park" was a terrible idea, but that's not an indictment of towers in themselves, but of the ways they were built: far from the street, in parks or parking lots, and far way from each other, hurting the urban fabric.

Some urbanists also say that having an aesthetic city is a boon to city life, which is defensible. But then again, what is an attractive city? Many urbanists in North America are influenced by Europe, which is true has better urban practices than us for the most part. But the European model is classical, one of orderly blocks of harmonious buildings.
Paris
Amsterdam
 I'm certainly not denying anyone the right to like these types of cities of harmonious buildings all with the same size and look. But the cities closest to my own heart are much different. I prefer the Japanese cities full of mismatched buildings, old and young together. To my eyes, they look "organic", they react and grow depending on what the residents need and desire whereas European cities look frozen in time.
Odawara

Osaka
Tokyo

Tokyo at night (Shinjuku)
Sendai, the pedestrian bridges are horrors according to some urbanists, I like them
And it's not like one could say that Japanese cities don't work at creating life on the street and at favoring active modes of transport. They work at achieving what urbanists set out to achieve. So is the European model really superior? Or can people agree to disagree whether ordered buildings and organic developments are best and more pleasant?

And the idea that harmonious buildings with similar heights are necessary to attract pedestrian life spits in the face of my own experience in Montréal, where Ste-Catherine street is one of the most vibrant commercial arterial street, where I love to go. And buildings over there are certainly not harmonious:
Ste-Catherine street, a look at the buildings flanking the street
OK, so you have large 6,7,8-story buildings, small 2,3-story buildings and a building almost like a skyscraper quite near. Those who favor "harmony" would say that this is pretty bad, plus some are recent of concrete, steel or glass, whereas others are in brick or stone, quite eclectic.

But for a pedestrian, here is what it looks like most of the time:
Ste-Catherine street: pedestrian point of view 1
Ste-Catherine street: pedestrian point of view2
As a pedestrian, I mainly look down, not up, and am attracted to the details of the buildings next to me, the shape and size of buildings of the farther side are in my peripheral vision only, I don't actually pay heed to them, and I can't even see how tall the buildings closer to me are unless I tilt my head back, and who walks around doing that? And do the people there seem repulsed by the eclectic buildings on either side of the street? Of course not, as you can see, it's full of people. So I am quite skeptical of the "common knowledge" of some that height limits and harmony are needed for cities to fulfill their purpose.

There is also always the possibility that we might have gotten it wrong in some way, which should raise some strong alarms, because this wouldn't be the first time we got it wrong.

The precedent, how arrogance and ignorance conspired to create sprawl

 

One big reason why I am wary of imposing preferences through zoning is that this was largely done after WWII. Much of the development rules we have implemented in the past 60 years were decided by elites who assumed that their own preferences were everyone else's too, and who decided to adopt rules to allow as many people as possible to live the same way they lived.

Essentially, the elites in the post-WWII era were big car lovers for the most part. They saw cars as a very fast and efficient way to get around. They were also often rich and loved the big estates the rich largely used to live in. So when they started making rules to guide urban developments, they took their own preferences and tried to adapt them so that people could live as much like they wanted to live as possible.

The huge estate was thus converted into a middle-class single-family home with a large lawn, a small replica of the rich estate. This model was the one favored by planning agencies, which imposed them on most new developments through zoning.

Being car lovers, they decided that it was the government's responsibility to see that road capacity and parking amount were sufficient to allow everyone to drive everywhere. Now this has not been possible everywhere, and some cities refused the changes that it would have entailed (New York, San Francisco, etc...) but in many American cities, they have essentially managed it, with cars having 90+% of the share of all trips. Something that would never have been possible unless governments spent fortunes to provide wide roads exclusively for cars and guaranteeing sufficient parking through parking minimum rules. The funding model chosen to fund all this was all about taking the expenses of this lifestyle away to make it as cheap as possible... by making the costs weigh upon everyone for it.

By doing so, they made cities almost unwalkable and made transit horribly uncompetitive, but they didn't care, because their preference was the car and they assumed that everyone would have the same preference. It wasn't evil intent, they thought that they were adapting society for more efficiency in transport and making sure that people would have the housing everyone should desire, because they sure did.

So the elites imposed their own preferences on us, and it created sprawl that most now see as an inefficient and terrible way to build cities.

Keeping that in mind, I am wary of urbanists deciding what we should impose as developments instead of sprawl. Maybe it makes a lot of sense to do things these ways and I may even agree with many of these recommendations. But I think imposing preferences is wrong. Not everyone likes the same thing and I don't think adopting rules to create one's preferred urban environment by banning any alternative is reasonable.

Wednesday, April 23, 2014

Les escaliers de Montréal vs towers of Toronto

As a quasi-follow up to the previous article about height and zoning, a comparison, between Toronto and Montréal, which despite being two Canadian cities have followed very different development models.

Les escaliers de Montréal, or Montréal, multiplex city


Montréal's housing stock is overwhelmingly made up of what is called a "multiplex", essentially duplexes, triplexes and more, apartment units built over each other in a same building. The main difference between them and apartment blocs as we see it is that:
1- They are 2- or 3-stories high
2- There are multiple doors to the outside, generally one per apartment

I'm not joking when I say it is overwhelmingly represented, we have square kilometers of the stuff, as the following picture I took from Mount Royal demonstrates. Basically all you can see there is multiplexes:

Multiplexes as far as the eye can see
(All images are clickable for larger formats)

When Montréal started growing with the first urban migration, the multiplex was the building that people decided to build. And one very particular characteristic of Montréal housing is the exterior staircase.








These photos run the gamut from poor housing to rich housing, from old buildings to new ones.

Tourists often find this astonishing, considering how we have ice and snow 5 months a year that residents need to climb up and down metal staircases many times each day. The reason for them is not well known, I've heard two theories.

The first is that the city government wanted to avoid having buildings too close to the street, so they mandated setbacks, which reduced the amount of each lot on which buildings could be built. So to save space, the builders chose to take the stairs to apartments outside of the building.

The second is that builders wanted to reduce communal interior space so as to reduce the amount of useless space they would have to heat during the winter, so with stairs to apartments being outside, only the apartments themselves had to be heated during the cold months.

Anyway, we're stuck with them, and we're in fact even proud of them as a defining characteristic of our city.

Anyway, that is what most of Montréal looks like, blocks upon blocks of multiplex apartments, with a variety of apartments in each, some bigger, some smaller.

The towers of Toronto


Toronto is a more recent city, and it shows, as the traditional North American housing dichotomy of single-family homes and huge towers is in full swing there. In fact, on a trip there, as someone used to Montréal neighborhoods, I was shocked to see the dearth of low-rise apartments in Toronto. Here is what it looked like from the CN Tower:
Toronto from the CN Tower, looking at the towers built around the main subway line
Photo from the same place, just looking a bit to the left, seas of single-family homes
A zoom of the tower groupings in the Toronto region
Zoom on the houses

Okay, it's hard to see these houses that are 1 or 2 kilometers away from the towers, so I'm going to use Google Street View to show what they look like.

Now, to be fair, for single-family homes, detached or semi-detached, they are pretty dense. 25 to 35 units per hectare. But this is still very far from the Montréal multiplex neighborhoods that have 100 units per hectare and more, and up to 20 000 people per square kilometer.

So Toronto has really little middle-ground in terms of housing between these houses and the condo towers closer to subway stations and to downtown. Low-rise and even mid-rise apartments are rare.

Some numbers


Fortunately, I found some numbers to back me up if some accuse me of stereotyping. The census that the federal government does every few years also counts the types of dwellings, and they make a fortuitous difference between low-rise apartments and mid-rise and high-rise apartments. So here is what the housing stock looks like in Montréal, Toronto and Vancouver, for fun.

So I wasn't kidding when I said that multiplexes dominated Montréal. Add apartments with less than 5 stories and duplexes together, and they make up 72,6% of all housing units in the city of Montréal! Meanwhile, detached and semi-detached houses make up a mere 10,8% of Montréal's housing units. On the other hand, in Toronto, duplexes and low-rise apartments make up less than 20% of the housing stock, but over 40% of units are in apartment buildings of 5 stories and more, and 33,2% of Toronto's housing is in the form of detached and semi-detached houses.
Percentage of housing units per type in the main city

For comparison's sake, Vancouver is closer to Toronto too, with very, very few low-rise apartments. There is a significant amount of duplexes, which they favor over semi-detached houses it seems. I've made a mistake in importing the data for Vancouver (my Excel is in French and uses commas for decimals and spaces for thousand separation, census data uses dots and commas as thousand separation, no end of problems for me, thanks to GRIDS Vancouver for pointing it out).

Vancouver is between Montréal and Toronto, in a way it's more balanced in terms of housing. Whereas Montréal is predominantly low-rise apartments and Toronto is mostly high-rise apartments and houses, Vancouver has a mix of the three.

Now, both Montréal and Toronto were merged with former suburbs, so let's see what housing looks like over the entire metropolitan regions, to compare apples to apples.

Percentage of housing units per type in the metropolitan regions
OK, so including suburbs, we see a major increase in the proportion of houses, of course. But even then, multiplexes and duplexes make up most of Montréal's housing. Toronto still has a very small amount of low-rise apartments and duplexes, but even the suburbs have big apartment blocs. Vancouver seems more balanced here, largely because the suburbs, especially Richmond, have a lot of low-rise condos.

If you're curious, here's what the housing stock of the suburbs look like (in other words, the CMA houses minus the main city)
Percentage of housing units per type in the suburbs only
Even in the suburbs, in Toronto the amount of units in big apartment blocs is nearly the triple of those in low-rise apartments.

And does this mean that Montréal is less dense than Toronto and Vancouver? Not really. Though Vancouver's and Toronto's highest density neighborhoods have higher density than Montréal, Montréal has much more mid-density neighborhoods (7 000 to 15 000 people per square kilometer). So the population-adjusted average density for the CMA of each city is 5 400/square kilometer for Toronto, 5 000 for Montréal and 4 500 for Vancouver.
Census tracts ordered by density for the three cities

Now, why this difference? Well, either I'm obsessing over this or it's really at the root of everything, but I think the answer is zoning. Euclidian zoning is all about imposing a certain housing type on developments and protecting current neighborhoods from changing their housing mix. It's simply that Montréal, as an older city, had already begun building the next step in the typical evolution of cities (sparse houses -> dense houses -> low-rise duplexes and apartments -> mid-rises -> high-rises) when zoning hit. So as there was already a lot of low-rise units around, the zoning code simply allowed them in a lot of the city. On the other hand, Toronto was smaller when zoning arrived, so what got frozen was the dense houses of the time. Since building apartments is illegal in most areas in Toronto, even near the downtown area, they build extremely dense and tall apartment blocs in the land where they can build them. Same thing for Vancouver, but to a lesser extent as they have been allowing low-rise condos near downtown or in certain areas (like Richmond).

Here are the zoning maps for Toronto and Vancouver as proof:
Toronto zoning map
The orange is zoned for high apartment buildings (condo towers and the like). The map throws a curveball in that the yellow area includes 5 different zones: Residential, Residential Detached, Residential Semi-detached, Residential Townhouse and Residential Multiple Dwelling. Most of these have limits on density that make it hard to build apartments though.

Vancouver zoning map
All the zones in white on that map are zoned exclusively for detached houses. Though they have allowed laneway houses to densify them through the back door. It would have been better (though politically more difficult) to simply permit the replacement of houses with low-rise apartments piecemeal. The yellow zones also allow duplexes, and that's it (be careful, what looks like yellow sometimes is pale orange, which is the "multiple dwellings" zone, for low-rise condos). The few places that allow low-rise and mid-rise conversions create an artificial land shortage for new developments near the downtown area. This increases the value of land to the point where it is so expensive that low-rise condos are actually no longer cheaper than high-rises.

Over time, the allowed housing types in the city may "infect" the culture. For instance, even Toronto suburbs keep to the central city dichotomy of tall apartment blocs in a sea of houses, whereas Montréal suburbs still build a significant amount of low-rise apartments and condos.

Anyway, I think this demonstrates my point in the last article. When your zoning restricts low-rise and mid-rise density in most of the city, you get a lot of high-rises, because that's the only way the city can keep growing with zoning as it is. Montréal had the chance of having a lot of low-rise walk-ups when zoning hit, which allows them to be built as of right, which reduces a lot the pressure to build high-rises, and offers more family-friendly housing besides houses. Consequently, though high-rises do sprout up in a few places in Montréal, they have been much less common.