[Talk-transit] [Talk-gb-westmidlands] Naptan alignment

Tue Mar 31 23:08:46 BST 2009

Andy

"Town" is an optional field in NaPTAN and is either not used or is used
inconsistently ... it was included in the NaPTAN spec for legacy reasons,
but is not used in any mainstream information systems.  I suspect that the
missing stops may well not have this field populated - or populated in an
inconsistent way.

Your comments on bus stop locations are noted - and I broadly agree.  My
point was that shelters in many places in my experience are not closely
related to the bus stopping position - and therefore they should be mapped
as a piece of street furniture, but not used per se to define a bus stop
location.  There are even bus shelters which no longer have any operational
function other than to earn revenue for the advertising company that owns
them!

Roger

-----Original Message-----
From: Andy Robinson (blackadder-lists) [mailto:ajrlists at googlemail.com] 
Sent: 31 March 2009 22:50
To: roger at slevin.plus.com; 'Peter Miller'
Cc: talk-transit at openstreetmap.org; Talk-gb-westmidlands at openstreetmap.org;
'Brian Prangle'
Subject: RE: [Talk-transit] [Talk-gb-westmidlands] Naptan alignment

Roger Slevin [mailto:roger at slevin.plus.com] wrote:
>Sent: 31 March 2009 10:16 PM
>To: 'Peter Miller'; 'Andy Robinson (blackadder-lists)'
>Cc: talk-transit at openstreetmap.org; Talk-gb-westmidlands at openstreetmap.org;
>'Brian Prangle'
>Subject: RE: [Talk-transit] [Talk-gb-westmidlands] Naptan alignment
>
>Peter
>
>I think it is important to separate out the infrastructure of shelters from
>the function of the bus stop - the shelter is often located where it can be
>fitted in ... and it can be mapped as a physical object.  A bus stop
>represents a function - the boarding or alighting of passengers.  It may be
>indicated in the physical world by a "pole in the ground" - which might be
>close to the roadside, or might be at the back of the footway.  In my view
>the "stop" that NaPTAN records represent is the point at which passengers
>board or alight ... either the point marked by the pole in the ground if it
>is close to the roadside, or a similar point which might be indicated by a
>post displaced from the roadside (or it might simply be a point which is
>not
>marked - but is clearly recognised by custom and practice.  If there is a
>lay-by, then this is a widening of the road carriageway - the bus stop
>location should still be close to the edge of the footway at the back of
>the
>lay-by.  Taking your three (?) possibilities, I think all this means that
>it
>is what you labelled "4".

In reality the buses mainly stop where the people are standing waiting for
them and in practice of course they generally stand by the stop or at the
front of the shelter ;-) Jo public doesn't really care (and nor do we in
mapping) where the bus doors are supposed to open. The main caveat to this
is that I generally find a bus will pull fully into a lay-by if its empty
and the driver can see that passengers are waiting, otherwise they ignore
the lay-by and hold up traffic!

I've come across in rural areas where the shelter and the associated stop
are at entirely different locations but that doesn't appear to be the case
in Birmingham. So I can imagine that in some places the chelter will be one
node and the bus stop another.

>
>By the way - for those importing data for Birmingham, there was mention
>earlier this evening of "the marker for stops in Birmingham" in the context
>of stops that might be missing.  I am unclear what this marker is - as
>NaPTAN does not contain a marker for Birmingham, per se.  I can think of
>ways this might have been determined using the NPTG locality association  -
>is that what has been done?  If so the missing stops may simply be in a
>child locality which hasn't been correctly associated with Birmingham as
>the
>parent locality.

The NaPTAN has a "Town" element and those with BIRMINGHAM on that element
was filtered for the trial import. See the right hand RAW data column at:
http://wiki.openstreetmap.org/wiki/NaPTAN/Birmingham_Trial 

Its not a big deal if we missed some. The purpose of the trial import was to
have something to work with to iron out the questions before we roll out
across the country.

Cheers

Andy

>
>Best wishes
>
>Roger
>
>-----Original Message-----
>From: talk-transit-bounces at openstreetmap.org
>[mailto:talk-transit-bounces at openstreetmap.org] On Behalf Of Peter Miller
>Sent: 31 March 2009 20:51
>To: Andy Robinson (blackadder-lists)
>Cc: talk-transit at openstreetmap.org; Talk-gb-westmidlands at openstreetmap.org;
>'Brian Prangle'
>Subject: Re: [Talk-transit] [Talk-gb-westmidlands] Naptan alignment
>
>
>On 31 Mar 2009, at 20:22, Andy Robinson (blackadder-lists) wrote:
>
>> Peter Miller [mailto:petermiller63 at googlemail.com] On Behalf Of Peter
>> Miller wrote:
>>>
>>> 4) I notice that sometimes the NaPTAN stop and the OSM one are some
>>> significant distance apart which begs the question about which one is
>>> right.
>>
>> I've noted this too. I'm going to do a precise check in my area to
>> see what
>> accuracy I place on the NaPTAN positions. I've also from today
>> started to be
>> more precise about getting the position of bus stops when I survey.
>> I should
>> be within 0.5m +/- the GPS accuracy (generally sub 5m with this
>> Legend HCx I
>> use).
>
>If you are getting that precise it will be useful to agree where the
>stop should be. We might have a number of points
>
>1) A pole and/or a shelter
>3) Optionally a lay-by where the vehicle stops
>4) A spot where one would expect to stand to get onto the bus
>(opposite the door).
>
>Can I suggest that it might be appropriate to use the position of the
>pole and/or shelter as the reference for the bus stop and applications
>should then assume that the bus stops at the road edge with its doors
>at the nearest point to the shelter. If that is not the case then
>possibly we need a 'stopping point' node next to the road to show
>where the front doors of the vehicle would be.
>
>Should we also create a 'lay_by' or 'bay' attribute to say if there is
>a place for the vehicle to pull in to pick up passenger. It might be
>neat to be able to describe what sort of facility is provided. In some
>places it will be a pull-in pull-out bay, in others it might be a pull
>up, reverse out bay. If we have that information then future rendering
>engines will be able to get it right.
>
>This is what I mean by pull-in pull-out
>http://www.palmengineering.com/images/busBay4.jpg
>
>And this is a Pull-in reverse-out one
>http://www.broward.org/bct/images/browardcentralterminal.gif
>
>
>
>
>Regards,
>
>
>
>Peter
>
>
>>
>>
>> Cheers
>>
>> Andy
>>
>>>
>>>
>>> Anyway, it looks like the detective work is now starts! Great work.
>>>
>>>
>>>
>>> Regards,
>>>
>>>
>>>
>>>> Cheers
>>>>
>>>> Andy
>>>>
>>>>> -----Original Message-----
>>>>> From: talk-gb-westmidlands-bounces at openstreetmap.org [mailto:talk-gb-
>>>>> westmidlands-bounces at openstreetmap.org] On Behalf Of Brian Prangle
>>>>> Sent: 31 March 2009 9:46 AM
>>>>> To: Talk-gb-westmidlands at openstreetmap.org; talk-
>>> transit at openstreetmap.org
>>>>> ;
>>>>> Thomas Wood
>>>>> Subject: [Talk-gb-westmidlands] Naptan alignment
>>>>>
>>>>> Thomas
>>>>>
>>>>> I've also looked at Google maps and their alignment is off too in
>>>>> exactly
>>>>> the same way ours is in areas I know well and have surveyed, so I
>>>>> guess
>>>>> it's down to the NaPTAN data. There are examples where I know the
>>>>> bus stops
>>>>> are in a row along the street (Corporation Street  and Acocks Green
>>>>> Village
>>>>> for example) but NapTAN has one or two skewed from the line by
>>>>> several
>>>>> metres.  Currently I favour correcting the NapTAN data  to what we
>>>>> know on
>>>>> the ground, but until a consensus emerges I'm laying off the urge
>>>>> to
>>>>> correct it.
>>>>>
>>>>> Regards
>>>>>
>>>>> Brian
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Talk-transit mailing list
>>>> Talk-transit at openstreetmap.org
>>>> http://lists.openstreetmap.org/listinfo/talk-transit
>>
>>
>
>
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