Building Compact Cities

by Bluesteel

A city’s compactness is a compromise. On one side, a city can be spread-out — giving the advantages of cheap construction costs and plenty of green areas and roads, but also long commutes and dependence on cars. On the other hand, a compact city allows shorter commutes, better public transport, more services and nearby jobs, but suffers the disadvantages of overcrowded roads and noise pollution.

The primary issue boils down to roads. For roads not to be overcrowded, there must be plenty of them, and the population density cannot be too high. But when people’s homes are spread out, their need to travel increases, creating congestion and the requirement for more roads.

The solution often employed when a city’s roads aren’t up to the task is to put some of them underground — normally major thoroughfares. This kind of retrofitting is not cheap, and is normally avoided when building new cities.

But what if we put roads underground from Day One? Just lay out the road system on level -1,-2 and -3, and then lay the “real” roads out on the level above? Cars could get all the space they need — zipping around underground — and people could enjoy sun and fresh air without having to put up with the infernal noise of traffic. The whole city could be one large pedestrian zone with shops, parks and green spaces built to a scale appropriate for humans rather than cars.

Expensive? Unrealistic? Not when building a new city from scratch, as some developing countries, such as China, are doing today. If the site is a greenfield, building a concrete supported floor is not very expensive, as long as there is enough space to use proper tools for the job. If the buildings are tall, the additional expense per square meter should not be excessive.

The advantages would go far beyond making the city more pleasant. With roads underground, it would be possible to build more compactly while installing better infrastructure (you can have as many layers of roads as you desire!). More compact with better infrastructure means more people within easy travel distance, so the likelihood that you and your spouse can find a job that exactly suits your specialization increases. Likewise, your employer is more likely to find customers for specialized products. A large, ultra-compact city is likely to make its citizens ultra-productive, giving economic yields that will pay for the additional building costs many times over. More inhabitants pr square km will also make it cheaper for the city to supply services to its inhabitants, either it be electricity and water or policing and health services.

Now that we’ve convinced ourselves that we wish to build as tall and compact as possible and can do so while maintaining a pleasant living environment, why don’t we see how far we can pull the string? Let’s not just put one layer of roads in the ground — make it three! At the bottom we put thoroughgoing motorways and subways. Then we have a layer for cars, and above that one for buses.

But let’s not finish yet! Since we are building the whole city from a greenfield, we can install more gadgets than a sedate, mature city that is only slowly become dense. Let’s put in gondola lifts between some of the tallest buildings, creating a web of continuously moving lifts that you can hop on without having to dig out a timetable before leaving home. Placing the stations at somewhere between the 30th and 40th floors could be suitable, and at around the same level we can put in public shopping floors interlinked with bridges between the buildings. This way we would get two levels of shops while creating an effective way of moving shorter distances: Take the gondolas a kilometer down the road toward your destination, then walk the last distance by foot. This “skystreet” should be linked with the street level by public lifts. Again, since all this is installed when the buildings are built, the additional cost will be moderate, and gondolas are quite capable when moving large numbers of people shorter distances.

To complete the city, decorate it with plenty of trees and green. Plant trees at street level, but make the rooftops into parks, too. Now do we have a dense city that rivals suburban life?

Bluesteel is a mechanical engineer and MBA graduate from Norway, currently working in the oil industry. When he is not blogging, he enjoys skiing in winter and bicycling in summer.

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  1. I am very sympathetic to these ideas, especially density and reducing the dominance of cars in cities. I just wonder what the health and safety risks would be of putting so much traffic underground. What if we built tree covered hills around cities with parking garages inside, linked to subways and other forms of public transport throughout the city center?

    1. Regarding health and safety of having traffic underground, it will have to be addresssed, but solutions exist and are implemented in tunnel projects.

      There must be a ventilation system, with vents well above street level. There are also systems in place for removing pollutants (dust) from the air in a tunnel.

      An underground fire would have to be addressed - the smoke would have to be diverted away. There should be openings at regular intervals, for instance at each intersection. There must be staircases for people to evacuate to ground level.

      Putting parking garages "outside" the area in question is a common approach (UC Irvine campus is an example), but transport will then be by foot or tram and this isn't that efficient.

  2. What you've outlined is an expensive and silly (not to mention city-deadening) way to build densely. Here's an idea: how about we build low- and mid-rise buildings in a pattern where building coverage is 80% or more of the cities total land area, separated by really narrow streets? You know, like how humans have been building dense, pedestrian-oriented places for thousands of years?

    Check out some of this guy's ideas:

    All you've suggested is the finest dystopian concepts of the 20s and 50s, wrapped up in a pretty green bow.

    1. The problem with really narrow streets is that there won't be sufficient place for the traffic :)
      Building low and mid-rise building means building something similar to LA, won't it? And then you'd get traffic jams, and you 'd have to build some really large motorways...

      As for this being like dystopian concepts of the 20s and 50s - no, it's not.
      The problem with these, and most "radical" design concepts imagined is that they draw up the city as a "monument" to be admired and not as a place to live. One ends up with really large scales, wide avenues, big parks separating the buildings and long straight roads. In other words - a city where one can't walk. Brazilia would be a typical example, I've heard (never been there though). I have been to Paris, and it is a bit of the same. Or Shanghai, or any other large modern city. (And not to forget Astana, Kazhakstan:

  3. Here is an example of a Koolhaas-planned new city with cars underground: From the article:

    "Almere looks so much like today’s idea of how we’d like our cities to someday be—dense, architecturally engaging, humane, and eco-thoughtful—that is, almost a cartoon."

    1. yes, I've seen some examples doing this very well.
      Nearby where I live (Sandvika, Norway) there is a city block where 1 street has been put under the top level street. This street is used to access parking that has been placed in the basement of all the houses. What I'm thinking is to use this underground road as the primary transportation channel and have the road on top as a pedestrian line.

      The whole clue is that this can only be done if building the whole city from scratch! And the underground street must be well lit up and pleasantly designed.

  4. This also brings to mind Richard Register's notion of the vertical city: I think the first commenter had in mind something like this from the 1920s:

    1. Yes, I've read Richard Register's piece and agree a lot with it. The Popular Science picture from 1925 isn't that bad either, the city looks quite a friendly place with people living on friendly verandas on the top and having their workplace very nearby in the stories below. And the pedestrian environment is excellently free from wheeled traffic.

  5. I'd get rid of the bus layer, and all of the fume problems which it would entail. If you pour a concrete floor for the bus to run on, the extra cost for rail will be a rounding error, and over their lifetime, the vehicles cost about the same. The best solution would be a pair of local tracks added to the subway level, which should be right below the street for easier access on foot.

  6. I've always thought the buses would be electrical trolley buses - that is no diesel fumes :)
    Buses have an advantage over subways though, and that is that they are flexible!


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