The comparison between SkyCycle – a proposal to create a network of strategic cycling routes above London’s radial railway lines – and the City of London’s much maligned network of (unbuilt or demolished) upper level walkways is one worthy of attention.
1. The City of London “Pedways” often paralleled routes at street level. When they did so they effectively split the pedestrian flow between upper level and street level – thus typically making neither level particularly/sufficiently vibrant. This is why most of them did not work or were resisted from being built in the first place.
However, as all good students of spatial networks understand, not all links are equal. When upper level walkways genuinely create routes that are not available at ground level then the evidence of observation surveys shows that they can be very well used. Some of the upper level routes through the Barbican are as well used as ground level residential streets elsewhere in London. Reality is, as always, more subtle than simplistic classification.
2. In contrast, SkyCycle follows railway lines that have historically created morphological “fissures” in the street network either side of them. In this way SkyCycle does not recreate routes that are already available. Instead, it create new routes.
3. Spatially, these SkyCycle routes have two important characteristics:
a) because they connect directly from the edge of London to the centre, linking to the ground level at accessible points in the street network (identified by Space Syntax through spatial accessibility analysis) SkyCycle routes add to London’s “foreground network” of important arterials (the red and orange links in a Space Syntax map of London).
SkyCycle does not propose to take any cycling away from these major arterials, which should be the subject of roadspace design exercises of their own. It therefore adds capacity to London’s strategic route network.
b) because they link to the ground level at approximately one kilometre intervals, SkyCycle routes operate at a more global scale than many of London’s streets. Skycycle does not therefore propose to replace local cycling infrastructure – because that is a geometrical impossibility.
So, SkyCycle isn’t at all like the Pedways, which were often, but not always, geometrically misconceived. Instead, SkyCycle is designed to work in sync with London’s existing street network.
Let the discussion continue, informed by relevant and considered comparisons, evidence and analysis.