[Liverpool] A27 continuity on OSM

[Sebastian Arcus]

Following on from the discussion tonight about possible continuity 
errors on A27 on OpenStreetMap - I've just checked it using Navit. I've 
set the position on Eastbourne/Polegate and destination at the other end 
in Portsmouth - where the M275 starts. Navit seems to be happy to route 
on A27 all the way - without any deviation. The map I have in Navit has 
just been downloaded last week - so maybe somebody has rectified A27 in 
the meanwhile.

Another explanation might be connected with the routing engine used by 
the navigation software. For a while Navit use to do the same for me - 
suggest that I come off a main road or A road and follow some strange 
shortcut through 20mph roads in the middle of some housing estate - in 
order to save 0.3 miles of the total route. I've adjusted the weights on 
the various type of roads in the Navit config - so that it favours a bit 
more faster roads when choosing a route - and it seems to suggest saner 
routes. However, on occasion I still have trouble convincing it to stick 
with motorways - and it will suggest entire sections of 30-40 miles 
through A roads which I happen to know that are full of traffic lights 
every few hundred yards - just because it is convinced it will save few 
miles by going that way.

Depending on what navigation software is used - similar symptoms might 
explain strange detours off the main road.

Sebastian