Helical perimeter blocks would make cyclists’ lives easy

Any purpose-built bicycle city really would need to be dense. That would not be to negate the possibility of riding in an athletic manner on a bike built for speed, but to give a mother on a heavily laden bakfiets fair access to the same range of amenities as anyone else in her city. The same goes for the 8 year old or 80 year old who Bogotá’s former mayor Enrique Peñalosa famously included in his bicycle mobility plan for that city. He realised that if his city was going to make optimal use of its human capital it would have to change to be meritocratic in the way mobility was distributed. He was fortunate that Bogotá was sufficiently dense that something so cheap and accessible as bicycle transport could work.


Perimeter blocks are the sine qua non of a dense city. They really occupied architects’ minds from the mid 1970s when it was recognised that solar-oriented slab blocks and tall point blocks may be very clever unto their own logic, but could not be cleverly assembled to frame a useful variety of public spaces. The perimeter block was the answer. What it sacrifices by way of ideal solar orientation to every apartment, it makes up for by generating two distinct kinds of space at ground level: vibrant streets on the outside and defensible space in a courtyard.


Also, as advocates of the low rise, high site coverage development paradigm have always been quick to point out, the perimeter block is the basic unit by which cities including Paris, Barcelona (pictured above) and Rome got to be dense without subjecting their populations to 3rd-world overcrowding. The good news for cycling is that perimeter blocks can also be designed to allow super-fast egress by bike.


If you have seen that video before, you will know a bike-egress perimeter block has already been built in Copenhagen. It is far from perfect though, with access galleries poised to throw cyclists through a glass balustrade in icy conditions, and only about half of the apartments being accessed from the sloped galleries.

In response I worked with a student last year to develop his project into a safe version, that would also have bike access to every apartment. (A link to that here.) Recently I’ve worked with a few more students on spiralling forms, this time looking at double and triple helixes. We have assumed that ramps would mainly be used to go down so could be as steep as allowed for disabled access (around 1:20 over long stretches without any landings).

Multiple helical perimeter blocks, as the name should imply, really mess with your head as an architect. In the end I nutted out the basics by playing with lego and encouraged my students to make study models, like these by a Polish exchange student.

I beg any architects who read this blog regularly to tell me how this might not be revolutionary. I think it is. I see high density housing having been caught in a state of paralysis since the mid nineteen seventies. It took the Danish firm BIG to put apartment typology back on the table as a subject that deserves more innovation. The contribution I have been able to make with the help of my students stems from a conviction, evident now across about a years worth of blog posts, that apartment dwellers with bikes should enjoy the same level of convenience that people living in suburbs get with their cars and internal access garaging. That means bringing the vehicle you use to go shopping (in this case a bike) with you into the secure confines of your abode. I’ll leave you with slide shows of two more multi-helical perimeter block projects from our latest studio here at the University of Tasmania.

Charlotte Morton.

Proposed double helical apartment development with engaged point blocks in Singapore.

Emily Guyot

Proposed tripple helical perimeter block in Copenhagen.


  1. crank says:

    “…apartment dwellers with bikes should enjoy the same level of convenience that people living in suburbs get with their cars and internal access garaging.” That is absolutely revolutionary, Dr Behooving.

    When I amass my personal fortune and buy up the crumbling commercial properties along the Yarra, Imma gonna build me some frikkin’ Velohomes. Actually, on that note, would you adapt designs for the specifics of properties facing a waterfront or similar?

  2. Jimm Pratt says:

    “… access galleries poised to throw cyclists through a glass balustrade in icy conditions…” (regarding the Copenhagen ‘8’ apartment complex in the suburb/subcity of Ørestad). Which is why there are now signs at the start of the ramps saying “no cycling on the ramps”. 🙂

    • Steven says:

      Those bloody signs went up while my book was in print. But the architects had told me cycling was the big idea behind the design concept. Oh, never mind!

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