Tactile paving
2016-06-13 12:24![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
In Britain there is a standard for tactile paving at the start and end of shared-use foot / cycling paths. It uses a short section of ridged paving slabs which can be laid with the ridges either along the direction of the path or across the direction of the path, to indicate which side is reserved for which mode of transport.
Transverse ridges
If you have small hard wheels, like many pushchairs or the front castors on many wheelchairs, transverse ridges are very bumpy and uncomfortable.
If you have large pneumatic wheels, like a bike, the wheel can ride over the ridges so it doesn't feel the bumps.
Transverse ridges are better for bikes
Longitudinal ridges
If you have two wheels and the ground is a bit slippery, longitudinal ridges can have a tramline effect which disrupts you steering and therefore balance, so they are less safe.
If you have four wheels, the tramline effect can't disrupt your balance and can be nice and smooth.
Longitudinal ridges are better for pushchairs
The standard
So obviously the standard is transverse ridges for the footway, and longitudinal ridges for the cycleway.
(I have a followup item with a plausible explanation!)
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Date: 2016-06-13 16:53 (UTC)If the reverse of the current situation is the only possible sensible configuration, then yes, there's no good option. But if some other configuration is better than either, and sufficiently different it's not confusing, then we could use that for new installations. Then there would be a long transition period, but at least once you were familiar with the types one particular piece of it would be unambiguous. You would avoid the problems of "sometimes it means this, sometimes it means the opposite" and "have to relay them simultaneously all over the country".
I'm not sure if you already knew no other configuration would work, or read my post as the opposite of what I was trying to say?
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Date: 2016-06-14 06:35 (UTC)no subject
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Date: 2016-06-15 08:13 (UTC)But it still sounds like they wouldn't be completely clear. The cycleway isn't really "walk with caution", it's more like "don't walk here at all" (at least in longwise, you could cross sideways).
I'm still not sure where I went wrong. I feel like the conversation was:
Tony: This would be better the other way round.
Lnr: But it would be hard to change because if you swap some of them over, then they're always ambiguous.
Jack: But even if they're better the other way round, they're still somewhat uncomfortable. maybe some OTHER design would BOTH be more comfortable AND be safe to install incrementally without making the meaning ambiguous.
Everyone: NO!
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Date: 2016-06-13 09:56 (UTC)But the comment did have a useful link to the Wikipedia page on the topic https://en.m.wikipedia.org/wiki/Tactile_paving and a very pertinent observation that the shared use paving somewhat disagrees with the transverse warning ridges you see on the approaches to stairs, and with longitudinal guidance ridges.
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Date: 2016-06-13 12:40 (UTC)(I am aware of them because I've participated in a couple of their pilot studies about how to meaningfully do motion capture on wheelchair users, in the interests of getting a better sense of how we interact with public spaces/transport/etc - they have an excellent set-up for testing all this stuff...)
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Date: 2016-06-13 13:09 (UTC)It is a pity that "shared space" is problematic - in Britain they often try to use it in places with lots of motor traffic, and as a result it isn't feasible in practice for vulnerable road users to meaningfully share the carriageway. In my limited experience Exhibition Road is mostly too busy to be really successful (except for the bit at the end with lots of restaurants). You can't really saunter across from the Science Museum to the V&A without your Green Cross Code.
More from the cycling point of view at https://aseasyasridingabike.wordpress.com/2016/03/09/removing-isnt-always-better-the-problem-with-the-shared-space-concept/ and http://www.aviewfromthecyclepath.com/2014/04/shared-space-revisited-hype-continues.html
I gather that people with poor vision have problems with very low-profile or missing curbs, and they and people with poor mobility have much more difficulty crossing traffic when there are no clear places where pedestrians have priority.
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Date: 2016-06-13 14:19 (UTC)How we do it here
Date: 2016-06-14 00:15 (UTC)On the street where my office is located, there's a "cycletrack", and I got to see how this was built. The cycletrack, curbside tree/street furniture RoW, and pedestrian walkway are all built on top of a unitary cast-in-place PCC "bathtub". This is then covered with a layer of blacktop which forms the base layer for the pavers. Once the pavers are installed and locked together with polymeric sand, another layer of blacktop is laid between two stringer courses to make the cycletrack, which is then painted with arrows and cycle icons.
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Date: 2016-06-14 07:21 (UTC)> Longitudinal ridges are better for pushchairs
Longitudinal ridges oppose side-slip, which is more dangerous to those on two wheels.
When climbing a hill, transverse ridges give better traction; a bike is likely to have some momentum to carry it through the market slabs, whereas a push-chair is likely to stop more quickly without power.
Or at least that was the rationale I deduced upon finding the slabs at the Nuffield Gym (nee Greens) end of the Coldhams Lane railway bridge, where traffic has either just turned left or sharp right when it meets the ribbed paving.
It is not obvious to me that either direction of tile is obviously better or worse for two than four wheels in all, or even most, situations.
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Date: 2016-06-15 05:10 (UTC)A bit of googling finds me this interesting small paper:
http://www.avon.nhs.uk/phnet/avonsafe/Cycling%20Injuries/Schepers%20and%20Klein%20Wolt%20Cycling%20research%20international.pdf
"Almost one fifth of the crashes [caused by the road surface] resulted from longitudinal grooves or raised edges in the road surface. A wheel can easily skid when crossing raised edges or tram rails at too small
an angle. The front wheel skidded and got stuck in the tram rails in a few cases. "
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Date: 2016-06-14 19:36 (UTC)That is, if they wanted to. I'm guessing they had some reason for this, although I can't see it.
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