Density: Where is the sweet spot?

We are currently facing several of the biggest challenges of our lifetime with climate change, over population, resource scarcities and rapid urbanization.   To embrace these challenges we need a change in our way of thinking, including a restructuring of the way we organize and operate our cities.  Many planners know that this includes rethinking urban density.  It is also known that this is a contentious issue.  The old guard status quo of endless cookie cutter suburban developments will exhaust our ability to face these challenges.  Moving the conversation forward requires restarting the conversation, starting with the question “Is there a right density?”

After reviewing numerous studies and urban planning sources, in almost all cases density is never cited as the sole important factor for successful, lively and vibrant cities. Density plays a role nonetheless and an important one in a larger comprehensive package of urban interventions.  Paying attention to the finer details for all aspects of the city built form and civic services will ultimately create a great place to live, work and play.  The question is not about how dense it should be but rather how density is done.

awesome rowhouse Montreal blue
Rowhouse developments like these have the same density as high rise towers but spread the density to cover more ground while avoiding awful downdraft winds and boring spaces.

The conclusion is inescapable; there should be much less focus on the numbers of density.  Not all density is equal, we can have a sea of high rises, but if the change is too drastic or you forget vital features like safe and inviting sidewalks or places to shop and eat, there may be little to no street life or sense of place.  Density needs to be grounded in its context. It will not succeed without the scale, form and details that create irresistibly interesting places.  These interesting places can be designed in such a way that it does not feel dense, but people still naturally want to be there.

Seville ped only

While we should always begin with the goal of creating interesting places where people will naturally gravitate to live, work and play, we can use density thresholds to inform and guide our decisions.


Montreal bidirectional protected bike lane with bus stop and bench with logo
A complete street design with a bidirectional protected bike lane with a floating bus stop.

How we get around is a big topic these days and it isn’t a surprise that many sources and studies offered density thresholds for successful public transportation and lower vehicle miles traveled.

Toronto historic streetcar
Toronto’s historic streetcars provide an example of the possible frequencies possible with denser built forms. It is however always recommended to provide dedicated right of way to ensure maximum reliability.

Sources like Paul Mees’ Transport for Suburbia question the validity of some well cited transit planning sources such as the 1955 Chicago Area Transportation Study (CATS), or Peter Newman in their expression of the importance of density for transit.  Mees’, using Metro Zurich (4.5 dwelling units per acre/32 persons per hectare[1][2]) as an example, argues that while density does play a role in higher transit usage. However there are other important factors which include governments maintaining control of the right to design the transit network, long term strategic planning, and fare rates.  Also important is the inclusion of an integrated pulse timed, cross city network of multimodal, transfer based routes.


Toronto streetcars
A human scaled and surface level streetcar system along a low density commercial strip in Toronto.

Patrick Condon in his Seven Rules for Sustainable Communities conducted a case study of the Vancouver streetcar neighbourhoods, and advocates for linear commercial corridors supported by transit.  Condon found that frequent bus service (7 minute headways) could be accomplished with 10 dwelling units per gross acre[3], while a streetcar could be supported with a density of 17-25 dwelling units per acre[4].  Condon argues that our greatest opportunity for creating sustainable suburbs is to focus investments in densification and transit along suburban low density commercial strips. Just 10% of a commercial strip would have to be developed at 40 dwelling units per acre increasing the average area density to 10 dwelling units per acre[4].

Most people have an average 5 minutes walking threshold.  Therefore to reduce car trips significantly the number of people with their necessary shopping of everyday goods and services within a 5 minute walk should be maximized. Often transit planning tends to focus on nodes, however this does not maximize the 5 minute catchment area.  Instead transit should be focused at commercial corridors where pedestrians can link various trips as they walk to and from the transit on their way to work.

Otherwise there are numerous studies and sources showing density is tied to fewer Vehicle Miles Travelled (VMT) and supporting alternative transportation modes.  One study conducting a comprehensive literature review cites a study by Larry Frank, which states that a 33% reduction of vehicle miles driven per day can be achieved with twice the density of the typical low density sprawl in addition to a diversity of uses, interconnected streets[5].  This was also confirmed by other separate studies[6] where the VMT and car ownership could be reduced 29-37% and 16% respectively by doubling the density.  To produce significant reductions in automobile work related trips, 50-70 employees per acre and 12 dwellings per acre is needed, while non-work trips are reduced above 75 employees per acre and 20 dwellings per acre[7].

Sustainability, Health, and Utility Cost Performance


Typical 3 storey row house design in Montreal.

A recent study analyzing the 2003 U.S. Residential Energy Consumption survey, and 2001 U.S. National Household Travel Survey found that Household carbon footprints increase until 4.7 persons per acre[2][8], afterwards decreasing per ten-fold increase in population density leveling out at 78 persons per acre[2] [8].  Keeping this in mind, towers and single family houses have the most surfaces (walls and roofs) per household exposed to the elements, increasing the energy usage required per household.  Patrick Condon pegs 20-65 dwelling units per acre[9] as the optimal range, which includes combinations of duplex, quadplex, townhouses, row-houses, and apartments.  All of these can be shaded by trees from both the sun and wind, and require less elaborate heating and elevator systems.  It is not enough simply to build in this density range, a compact organization of households must be ensured to promote good shading, encourage walking and biking while minimizing the need for parking and paved surfaces.

Montreal corner store Rona example
With higher densities it is possible to service local amenities at a lower cost per person.

Cost analysis studies show that it is less expensive to construct and operate infrastructure and services for denser developments instead of single family housing.  A Canada Mortgage and Housing Corporation (CMHC) study finds that alternative development principles with a finer mix of land uses, higher residential densities, a transit supportive street grid design, etc. would see approximately a 16% decrease in infrastructure construction cost per unit[10].

Montreal fine grain retail store.jpg
Smaller corner store sized produce or grocery stores help prevent food deserts.

Many cities are adopting strategies to become the healthiest city based on a wealth of studies providing evidence that 30 minutes of brisk physical activity is a free “super drug” that can help reduce the levels of obesity and diabetes which can be encouraged with compact, walkable environments[11].  One study found that for every 1% decrease of population living in dense areas would see 0.01-0.02% increased prevalence of obesity[12].  By creating compact, connected, safe and interesting places, people will naturally include walking or cycling in their everyday activities and errands.


Montreal fine grain retail
Fine grain mixed land use is the most efficient with retail uses typical occupying the first floor and residential uses occupying 1-2 floors above the ground floor.

Places to shop are crucial ingredients for creating interesting places.  Corner stores can act as community hubs, restaurants and bars are places to catch up with old friends and make new ones.  The corner store (1500 to 3000 sq ft)[13] is the smallest and most useful community oriented type of retail center.   Either stand alone or built into a mixed use building, a corner store can be economically sustainable with 5-6.25 dwelling units per acres[13][2] when sited on a primary street and located next to community buildings, parks, and schools.

Montreal supermarche neighbourhood centre
An example of a larger shopping center designed for an urban context with no surface parking. 

A neighbourhood center (50,000 to 70,000 sq ft) [14] offering the everyday goods and services required by households anchored with a supermarket, pharmacy and restaurant is often considered the core of the traditional neighbourhood.  To be economically sustainable a neighbourhood center needs 12-16 dwelling units per acre[14][2].


One can conclude that the density sweet spot ranges from 20-65 dwelling units per acre.  This can include combinations of duplex, quadplex, townhouses, row-houses, and apartments and is enough to support a cross-city multimodal network of high quality, reliable. frequent transit services, and the necessary neighbourhood retail goods and services while minimizing the Vehicle Miles Traveled, Household carbon footprint and energy usage.


Densification is a long term strategy, where the focus should be on increasing density incrementally targeting specific areas such as commercial corridors, or the densification of inner city neighbourhoods.

quaduplex edmonton
An example of an inner city neighbourhood quadplex in Edmonton, quadrupling the density on the same land and demonstrating the potential for densification.


Inner city neighbourhoods are a great place to focus densification strategies, as most of the 50-75 year old houses are nearing the end of their life.  These existing neighbourhoods can be incrementally densified without the drastic changes that drain existing community capital.  Authors like Dunham-Jones, Williamson, Campoli, and Von Hausen outline many changes for more compact inner suburbs such as legalizing infill, smaller lots, and secondary suites in the basement, garages, and laneway houses.  Cities can also allow the medium density housing options duplexes, townhouses, row-houses, quadplexes that conform to the existing scale and form, while also eliminating setbacks, replacing minimum with maximum parking requirements, allowing more creative shared parking solutions, and supporting a diversity of housing types, sizes, and occupancy types.

Similarly new suburbs should be designed more compactly using creative clusters, a mix of housing types, and thoughtful orientations to minimize the footprint, the need for parking and asphalt, and energy requirements.

David Sucher says that people will naturally want to live dense if you build interesting places.  Interesting places such as your bustling main street of your favourite trendy shops, restaurants, pubs or hang outs entice people naturally.  We need to turn our thinking on its head, focusing less on the hard numbers of density and more on the smaller details that collectively define great places.

rue Laurier Montreal retail street benches
Public seating in the form of benches give people the opportunity to take up public space and essentially extend their living room in denser environments.

These details start from the benches, streetlamps, and trees that reflect our pride and community spirit.  It also includes the great community buildings, public spaces and commercial retail spaces that offer community programming, the necessary shopping and services and places to gather.  It includes a comprehensive multi-modal transportation system that provides people with a more than a singular automobile choice.  Finally, it includes a mix of uses and housing options to meet the needs of a variety of families, ages, cultures and income levels.

Density by itself is not enough, it is one of many ingredients needed to make great communities. Density comes in many forms and should complement the existing neighbourhood character, using architecture and design to incrementally increase density while still matching the scale and context of the surroundings.  We have the tools and knowledge to make density beautiful, interesting and enjoyable, so that density does not seem dense.  It is not a question of how dense a neighbourhood should be but rather how the density is done.


  1. Mees 2010, p. 81.
  2. Converted using the 2011 Statistics Canada average household size
  3. Condon 2010, p. 72.
  4. Condon 2010, p. 75.
  5. Ewing et al. 2008, p.16.
  6. Holtzclaw
  7. Condon et al. 2001, p. 2.
  8. Jones et al. 2013, p. 901.
  9. Condon 2010, p. 98.
  10. CMHC
  11. Jeon et al. 2007, p. 750.
  12. Zhao et al. 2010, p. 786.
  13. Gibbs 2012, p. 5
  14. Gibbs 2012, p. 8

Consulting Services

Slow Streets Public Life Observations and Design Consulting

Slow Streets offers public life behavioural observation and street design consultation firm. Working with Slow Streets is a great investment because not only would you benefit from the expertise from an experienced city planning engineer but you would receive high quality and results-driven customer oriented service. Working with Slow Streets is critical for vibrant, economically sustainable cities because you will see an increase in the return on your investment such as increased rates of cycling, walking and transit, improved retail business success and improved public spaces.

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Building better cities for women – Women Mobility Survey results

By Darren Proulx

Research shows our behaviour is heavily influenced by our built environment. A neighbourhood with narrower streets, trees and smaller shops closer to home encourages us to walk more often. Adequate lighting, more street facing windows, more people around and fewer and slower cars make people feel safer.

women bike montreal


Jane Jacobs highlighted the need for allowing differing levels of privacy and social connections was vital to the wellbeing of a city and its people. Offering people the ability to balance their social contacts and privacy according to their own level of comfort is closely related to building a balanced urbanism that fosters improved safety for women. Building a complete neighbourhood ensures that their is a community that its residents can participate in. Because of the space required for car oriented urban development and street designs, they often only permit social interactions when you are outside of your car, which often tends to include the few steps between your car and your destination whether it be work, home or shopping. This means in cities that have been built around the car you often have to put in considerable effort to seek out those social interactions.

rue Laurier Montreal retail street benches

Designing our cities and streets around people permits the potential for social interactions along a walk in your local neighbourhood. Allowing men to get outside of their bubble and interact with more people in their own neighbourhood can help their mental health and reduce their insecurities, stress and anxieties. A city built around people invites more people out onto the streets at more times of the day, increased windows from more stores and increased visibility, all of which serves to enforce a self-regulating social framework and creates a more comforting environment for women.

retail street parklet rue beaubien montreal .jpg


This can be seen in communities like on Laurier Avenue in Montreal. With it’s combination of low vehicle volumes, many small retail stores, restaurant, services and public seating it creates an engaging, vibrant and inviting experience for everyone including women. Good urbanism that fosters safety for women starts where everyday life unfolds, at the street level with the street and walls. This can be influenced with its street and building designs and Slow Streets can help you get there. I was once told a story from an acquaintance that when she walked around Montreal with a group of females they were never harassed whereas in their extremely automobile oriented hometown the incidences increased dramatically.

Slow Streets recently conducted a Women Mobility Survey asking women directly how they typically got around, where and how often they were harassed and what design features made them feel safer. We will dive into some of the initial results here. We received over 600 responses from 6 continents, 31 countries and 195 cities. Most of the responses are concentrated in North America, South America and Europe.

The majority of responses were from those aged between 21 and 40 years old.

age brackets

The majority of responses were from white females.

race responses

The responses by income bracket are more evenly distributed with more responses at the high and low income brackets.

income bracket chart

The most common primary way of getting around were by personal automobile, public transportation, walking and cycling respectively.

Modal Chart

Walking was used a primary way of getting around the most frequently, followed by transit. Cycling was the mode that was the least frequently used, with the most responses stating never. Clearly more work needs to be done to improve conditions for cycling.

Walk, bike, transit mode share chart

Only 15.36% of respondents reported that they absolutely felt safe in their cities. Only 40.63% stated they absolutely felt safe to walk alone in the daytime. this reduces by half in the nighttime (22.91%). Only 24.06% stated they absolutely feel safe enough to cycle in their city. Clearly there is some work that needs to be done.

We asked where and and how often people experienced harassment.Verbal harassment is the most frequent on public streets.

verbal harrassment by location chart

We also asked whether people experienced physical harassment as well. Physical harassment is the most frequent on public transit. This highlights the need to improve safety on public transportation, perhaps by increasing frequency as described later.

physical harassment by location chart

We also asked what would make the respondents feel safer for three categories.

Top 5 ways to improve public streets:

  1. A lack of lighting
  2. Speed of cars
  3. Specific types of people
  4. A lack of people
  5. Lack of protected cycling lanes
  6. Interactions with cars

From this it becomes clear that slowing down the speeds and interactions with vehicles is important to improving the safety for women on our public streets. Creating safe, comfortable and inviting street environments will also assist in attracting more people. Having adequate lighting would be a part of the solution to create an inviting environment.

Top 5 ways to improve public spaces:

  1. A lack of lighting
  2. Specific types of people
  3. A lack of people
  4. Lack of businesses nearby
  5. Cleanliness
  6. State of repair

From this list it becomes clear that adopting the power of 10+ activities would assist in inviting people into spaces. Building a complete community to surround the public space is important to bring mixed uses at all times and introduce “eyes on the streets” at all times. Finally having a good maintenance and upkeep program is vital for making women feel safe to stay in public spaces. Having adequate lighting would be a part of the solution to create an inviting environment.

Top 5 ways to improve public transportation:

  1. Low service frequency
  2. A lack of lighting
  3. Specific types of people at stations and stops
  4. A lack of people
  5. Long walking distanaces
  6. Overcrowding

What’s really interesting to note is that women are saying that more frequent service is something they would prefer to improve their safety. This is over shorter walking distances. This reinforces the new wave style of connective transit network designs being promoted by the likes of Jarrett Walker. Therefore improving frequency at the expense of a slightly increased walking distance would not only improve safety for women but also improve the overall reliability and usefulness of the transit network.  Higher frequency would also mitigate overcrowding. Transit stations are often designed with hostile architecture with bare bones feature and elements, this would have to be changed to create a more welcoming environment for women. Having adequate lighting would be a part of the solution to create an inviting environment.

Slow Streets has the ability to draw more in-depth insights from these results and offer consultation services to improve cities specifically for the safety and wellbeing of women.

Montréal Urbanism – Why it works

By Darren Proulx

After having traveled around the world, I have been repeatedly saying that Montreal exhibits the best combination of urban elements I have seen anywhere. There are only a few cities that compare and Amsterdam is one of them. What makes it this way?

awesome rowhouse Montreal blue

For starters buildings in the residential neigbourhoods are at most 5 storeys tall. In addition to this the buildings are built in a rowhouse fashion (a series of taller, narrower houses built right next to each other along a block with no space or gaps between buildings. These are famous in Brooklyn or Amsterdam as other examples.) These rowhouses actually make these blocks quite dense, it is the equivalent of taking the height from a 30 storey tower and spreading the density over more surface area. In the photo example above, the building is actually split into three units one each floor, and knowing this neighbouhood most likely there are 2-3 room mates per floor. The result is you get a rich palette of details for your senses while you go along your daily tasks.

Can you spot the gnome? There is an overwhelming abundance of beauty and detail when you build neighbourhoods around this hidden density.


This density is not only for looks,  it also serves a very functional purpose as well. It provides convenience, by bringing your daily services and amenities closer to home or work. Whether this be a place to play with your children, a park to take a relaxing stroll through, bumping into known colleagues and having a sidewalk chat, or purchasing your everyday groceries, services or needs.

The density of people provided from this hidden density rowhousing makes all of this possible, right at your finger tips. In Little Italy there are hundreds of retail, restaurant, cafe and service stores within a 10 minute walk on 4 different retail streets and an indoor/outdoor market.

rue Laurier Montreal retail street benches


Little Italy Retail Streets

These services not only include “nice to haves” such as cafes or restaurants or bars but also include all the necessary services such as day cares, dry cleaning, phone stores, pharmacies, churches, societies, printing, repair supplies (such as the corner store sized Rona pictured below).

Montreal corner store Rona example

Montreal is also one of the first cities I have seen that readily adopts measures to temporarily transform parking or underutilized spaces into public spaces using LQC (light, quick and cost effective) materials. Further, to have this level of public investment in providing public spaces in the winters is unprecedented. The results are spectacular.

Finally the way that Montreal embraces its street art means that places that often do not “deserve” any attractions end up having some color and vibrancy splashed even in the oddest of places adding a bit of whimsy.

alley graffiti Montreal little italy

Let’s turn this rat race into a relaxed stroll

By Darren Proulx

Ratrace video screenshot

A few weeks ago I woke up to a video in my social media feed about the rat race we are living in. If you haven’t seen the video yet, here it is. In fact the before night I was at an event listening to the story of a start-up’s story of their rise. It included a lot of the classic Hollywood elements like him sleeping in his office and him being in debt by hundreds of thousands of dollars.

While the story was certainly inspiring. The underlying premise was terrifying, here was a guy that was trying to start a company to actually bring some good in the world and this is how we were treating him.

Are you tired of living in this rat race? This rat race video and the entrepreneur’s story really brought me back to the question about how we invest our resources and whether there is anything we could do to end this rat race and transform it into a relaxed stroll.


Amsterdam is consistently considered one of the happiest places. Yet it is built predominantly around the bicycle. What gives?


Back in the 70’s when they started to transition to the automobile like everyone else they said no and over the last 40 years they transformed themselves back into a city for people. Cornelia Dinca and Thomas Schlijper from Amsterdam have put together a great documentation of Amsterdam’s transformation from its car oriented past here.


Building a car oriented city increases the amount you have to earn in order to live comfortably, contributing to the rat race and this is whether or not you drive or not. A car is an expensive and depreciating investment (over $10,000 per year). Building a city around the automobile makes it more difficult for local businesses to thrive. Roads built primarily around moving the most vehicles through as quickly as possible are also expensive, putting a strain on city budgets. The cost for maintaining this system is passed onto all of us with higher taxes with a diminishing return with a less livable city and fewer great destinations.

parking lot photo

If you choose to opt of this rat race, even slightly less, you still pay for it. We all pay for it through the parking, through the piping and roads in the far edge suburbs. And what has all of this infrastructure solved, nothing it seems as our roads are still bumper to bumper in rush hour despite adding more and more lanes.




I like that this video addresses that we are stuck in a rat race, but it doesn’t address what the alternative looks like. So what does real happiness look like.

Amsterdam park

This is getting enough rest and having time to enjoy even just sitting still without anxiety. This is about enjoying your city without worrying about your phone or the need to buy something.


This is about connecting with your neighbours and acquaintances. This is spending time your loved ones.


This is about chatting with friends on a lazy Sunday afternoon.

Montreal cafe people chillaxing

This is the laughter or a smile from your child.

piano Montreal tactical urbanism

This is a mobility system safe enough that you don’t have a second job acting as your child’s chauffeur.

doubling up utrecht

For women this means you can comfortably navigate your own city safely without the need for a $10,000 a year accessory (a car).

women bike montreal

This is about not worrying about the safety of your children being run over or killed in a vehicle collision (vehicles are one of the top causes of child fatalities.)


All of this starts at the street level. We can change our streets to create a more enjoyable experience while you go about your daily business: work, live, play.


How about instead of designing our streets and neighbourhoods around speed to support this rat race we slow things down so that we can enjoy and connect with our own neighbourhoods and those living in them? It is time to transform this rat race into a relaxed stroll. Not only will our wallets thank us for it but we will get to enjoy our city more instead of having to go on vacation to find those experiences. If you want to improve your bottom line and create a more enjoyable city Slow Streets would be more than willing to help you achieve that.


Slow Streets AI, Coming Soon!

Cities invest billions of dollars in their streets, but are they maximizing the return on public investment from their streets? Are cities designing streets in a way that maximizes the health, safety, economic development and quality of life potential for their citizens? Most cities evaluate street designs based primarily on how quickly you can move the most vehicles through them. To evaluate the success of street designs in this manner fails to accurately capture the full impact of the design and the potential socio-economic benefits and impacts they provide.

What if you could measure how happy or disgruntled a street or public space design was making people? What if you could track how quickly people were walking because of a street design? What if we told you that you could now do that?

Slow Streets is excited to announce the unveiling of Slow Streets AI, a revolutionary and cutting edge new way to evaluate street and public space designs!

Slow Streets AI White Paper 2018-01-26

Slow Streets conducts behavioural observations of various street designs using artificial intelligence software which tracks and counts people and provides details such as their emotions, whether people were wearing glasses, had facial hair and their attributes such as age and gender. This provides data of how people actually travel and behave.

What are the impacts when you remove a curbside parking lane and replace it with a 60 km/hr curbside HOV lane? What are the impacts when you set back the retail buildings from the sidewalk with parking lots? What are the impacts when you lower the speed limit, provide protected bike lanes or parklets? People’s behaviours follow the street design and it has a direct impact on the social, economic and environmental success of cities. These are all scenarios that can be evaluated with Slow Streets AI.

Stay tuned! Over the next few weeks Slow Streets will unveil the capabilities of Slow Streets AI through a series of posts.

Women Mobility Survey and #UrbanDesign4Women Twitter Chat


Slow Streets UrbanDesign4Women Survey Flyer 2018-01-08

Happy New Year! Slow Streets would like to welcome you to the Women Mobility Survey and Twitter Chat!

Have you ever wondered if our city streets, mobility networks, and public spaces could be redesigned to enhance the wellbeing and safety of women and girls? We would like to share an important survey addressing this question. Prepared through a partnership of Slow Streets, Green Our Walls, UN Women-USNC LA with the support of Women in Cities International, this survey aims to evaluate the everyday experiences of women in public streets, public spaces and transit systems. The information you provide will help us design safer, more equitable cities for all.

The survey will be open until January 31th, 2018, and should take 5-10 minutes to complete. All answers will be kept strictly anonymous. If you share the survey link with the hashtag #urbandesign4women on Facebook, Instagram or Twitter, you will be entered for the chance to win a fabulous prize!  Please share this survey freely. Please get in touch with us at with any questions you may have about the survey.

Slow Streets UrbanDesign4Women Twitter Chat Flyer 2018-01-11

We launch our survey with a Twitter Chat on Thursday, January 11, 2018 at 12pm @UNWomenLA with partners @SlowStreets and @GreenOurWalls and under the hashtag #UrbanDesign4Women. We look forward to your insights to the conversation.

Please feel free to help us get the word out about the survey and Twitter chat!  Included below are tweet examples you could share with your followers.

We look forward to chatting with you!  


Join @UNWomenLA @GreenOurWalls & @SlowStreet  on Thursday January 11, 2018 for #urbandesign4women Twitter chat! Let’s discuss how we can make our communities safer for women and girls.

PARTICIPATE and SHARE the Follow @UNWomenLA twitter chat w/partners @GreenOurWalls @SlowStreets to discuss how we can make our communities safer for women and girls. #urbandesign4women

Did you know that you can win a fabulous prize and make a difference in our communities? Take and share this Women Mobility survey #urbandesign4women