[Talk-GB] Imaginery footpaths added by user "Gavaasuren"

[David Woolley]

On 18/08/14 10:59, SomeoneElse wrote:
> Whilst the existance of a highway=pedestrian area that isn't connected
> is an indication of something, it's usually just an indication of that
> mapping in a particular area is not complete.

Considering the longer term problems:

1) There needs to be better guidance to routing software developers on 
how to route when there are parallel features accessible on foot;

2) There needs to be a lot more mapping of barriers.

Ideally, the routing rule for foot needs to be something like that, 
subject to access and surface quality considerations, if there is no 
barrier between adjacent features, you may cross at any point between 
them.  In this case, there has probably been pressure to make life 
easier for the router.

I think this also came up recently with regard to central reservations 
on non-motorways.

The other difficult situation we have here is that pedestrian areas are 
mapped physically, as the actual area occupied, but most roads are 
mapped, abstractly, as an infinitely narrow line on the centre of the 
carriageway, so you will get a gap between the two and the router has to 
use some heuristics to decide whether that gap is bridgeable on foot.  I 
have seen cases where the pedestrian area was mapped out to the centre 
of the road, but I considered that wrong.  (In fact, mapping roads as 
areas will generally confuse routing software.)

Another variation of this routing problem is that of where is it 
reasonable to cross a road.  Ideally, physical barriers at the centre of 
the road should be mapped, and access restrictions put on any 
reservations that is not supposed to be used by the public, but the main 
consideration tends to be the level and speed of traffic and the 
visibility of that traffic, combined with whether or not there is a 
designated crossing point near enough to be used.

There really isn't enough information mapped to make a decision as to 
whether it will be safe to cross.  Also, a little old lady may not be 
safe crossing at an arbitrary point, whereas it will be no problem for a 
more able bodied person.  Some people may want to avoid pedestrian 
subways, particularly after dark.  Any mapping of crime levels in them 
is likely to be volatile and may even move the crime.

Particularly for residential roads, you might get into the dangerous 
area of mapping actual maximum speeds on rat runs, as, there is a road 
near  me with a 20mph limit, but, apart from speed bumps it is long and 
straight, so vehicles may get up to 40 mph between bumps, with 
visibility limited by parked cars.  The council policy is to only use 
passive enforcement.  Mapping that as 40 mph de facto, may encourage 
people to use it that way, but saying it is safe for little old ladies 
to cross at night, based on the 20 mph limit may also be wrong.

Maybe there is a need for a verification tool that renders additional 
random interconnections and crossing points, so that one can see whether 
there is a need to add barriers, and other hints, to prevent such routings.