Start/finish points that are not routable due to OSM data

[mvl22]

The following locations are not routable, due to them being in the midst of non-cycleable areas which are technically routable locally by bicycle but which can't be exited from, e.g. motorways or one-way systems.

I recommend these be manually adjusted, as routes from/to these specific locations will fail.

• -0.39483,51.487404 (Bicycles not denied from service station but surrounding connections are all motorways) http://www.openstreetmap.org/?mlat=51.48740&mlon=-0.39484#map=19/51.48740/-0.39484
• -1.574460,54.772446 (Resolves to footpath network that seems not to have any non-gated entry points) http://www.openstreetmap.org/?mlat=54.77245&mlon=-1.57446#map=19/54.77245/-1.57446

I used the script created by @Robinlovelace in 4a96267 and ran this through our batch routing system, which picks up these cases quickly.

This is not at this stage a complete list as I tried the batch on a server that only has about half of the UK loaded. I will edit this opening posting if more are found in future.

(It's on our list to fix these rare cases at engine level, but it's non-trivial because the local routability remains valid. Essentially we need a re-entrant algorithm that can invalidate a nearest point lookup if the other end is on a different network island and then second time around treat the local-only network as if it were bicycle=no even though it the data is bicycle=yes. I have a feeling that Simon has been doing some work on this general area recently but we don't have a stable engine implementation yet.)

[Robinlovelace]

Please can you put this in our main issue tracker (but only if it affects the PCT): https://github.com/npct/pct-shiny/issues - I would suggest we use a systematic method to move those 'unroutables'! Many thanks for finding them.