Saturday, 16 April 2016

Filtered permeability and how to do it better

If you ride a bicycle or walk in the newer areas of the city, or in Mill Woods or the area to the west side of the West Edmonton Mall, you probably will notice that between houses, there are paths. Some of them are wider, 2.5-3.2 metres and made of asphalt, intended as shared use paths, or 1.5 metre wide sidewalks. These are examples of filtered permeability. But it could be oh so much more.

The Dutch surprise surprise have a lot of filtered permeability. It makes cycle and walking journeys faster than cars in most cases, and allows connections that would be illogical to provide by car. You can offer a cycle path connection closer to the desire lines for example. You can have a small access to a residential area right near a traffic light controlled crossing for bikes and pedestrians even when there wouldn't be enough room to allow that access to exist by car. And it allows the maintaining of cycle and walling routes when you remove through traffic from areas that should be low volume and not the main routes by car.

Edmonton does not have good examples of filtered permeability. The paths are too narrow and join up with the road in awkward ways, sometimes without even a wheelchair ramp, they tend to have less good sightlines, sometimes blind corners, not good maintenance and with no divide between cyclists and pedestrians. We often use bollards in dangerous ways, with large T shaped metal bars that won't give, with nothing to mark that there is a bollard at night, or only a minute reflector.

Let's see what we can do to improve them. The Rantyhighwayman, a roadways designer in the UK who actually follows sane guidance and genuinely puts cyclists and pedestrians ahead of motor vehicles in much of his work, I know, shocker that the UK has this kind of person (note that I did not use plurals intentionally, but I did include a bit of sarcasm). He designed along with a few others, this cycle path:

It's quite a nice path, 3.1 metres wide (could be 3 metres if needed given the low expected volumes and the low importance on a grid wide scale) with a 2 metre wide sidewalk. I'd have liked it had they used grey tiles or concrete for the sidewalk, but he did what he did and it works well anyway. 

This is how to design out shortcuts. We obviously would change which side of the cycle path we ride on, but that aside and the yield markings would be replaced with a yield sign and sharks' teeth, there is practically nothing different. 

There is a reason for why the sidewalks also tend to be present. Given that these are narrower cycle paths and these are still quite close to home, it is much more likely that people will walk along here, and they often can cause the flow of cyclists to be interrupted to a degree that it's lowering the effectiveness of the cycleway. Even more so if people feel like it is attractive and pleasant to walk and that it feels competitive with cars. 

I came up with my own diagram for how this can work, assuming a 6.5 metre wide shortcut (including the grass and bushes) to work with: It's not much, but it does the job. When there isn't a lamppost, the area reserved to it just goes back to a sidewalk making it 2 metres again. An angled curb between cycle path and sidewalk will d

This filtered permeability is a major reason for why many cycle journeys are shorter than those made by car. Why not make them even more efficient, smoother and conflict free? 

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