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

Andy Robinson (blackadder-lists) ajrlists at googlemail.com
Tue Mar 31 20:59:30 BST 2009

Peter Miller [mailto:petermiller63 at googlemail.com] On Behalf Of Peter
Miller wrote:
>Sent: 31 March 2009 8:51 PM
>To: Andy Robinson (blackadder-lists)
>Cc: 'Brian Prangle'; Talk-gb-westmidlands at openstreetmap.org; talk-
>transit at openstreetmap.org; 'Thomas Wood'
>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).

I'm doing what's logical, which is to get as close as I can to take the
picture of the sign. I'll be within the stated accuracy of that. Mostly the
sign on shelters is at the end facing the arriving bus, but not always. If
its at the other end I tend to need to take two photos, one of the Asset
number which is usually on the side facing the direction of traffic and
another for the route/info sign. In which case I tend to drop the node
between the two points. For posts its easy to cycle up till the bike wheel
touches the post (hence the within 0.5m)

>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.

Buses in the midlands rarely stop where they are supposed to ;-)

>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.

That's a feature of the road, not the bus stop itself. Ideally we should
have a node on the highway with a lay-by tag but we get into left side right
side issues with that. For now I'm ignoring lay-bys' and other vehicle
positioning aspects.


>This is what I mean by pull-in pull-out
>And this is a Pull-in reverse-out one
>> 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
>>>> _______________________________________________
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