[Talk-transit] Summary of Public Transport Proposal Criticism

Michał Borsuk michal.borsuk at gmail.com
Mon Jan 24 09:10:05 GMT 2011


Am 24.01.2011 09:39, schrieb Roger Slevin:
> I have not been able to follow the large number of posts on this group in
> recent weeks - but I can confirm that stopareas are an important part of
> NaPTAN data in the UK, and are an important aspect of the way that stops
> data are used in journey planning applications.
This is true, but IMHO obsolete. They are used in situations where the 
routing application does not possess the information on the location of 
stops. OSM does have that information. Such places can be calculated, 
instead of being entered by hand.

>   It would be a pity if OSM
> decided they were not needed ... because they are needed by at least some
> USERS of the data.

As far as I understand the issue, stop areas are used to tie different 
stops into one "transferring area". This is a common concept, it exists 
in both Google Transit and HAFAS. But it could be easily replaced by a 
simple calculation of which stops are close enough to be considered "a 
pair of stops where the user can transfer". This would have the 
advantage over the existing approach by adding the ability to calculate 
different costs of transfer - static transfer tables have fixed transfer 
costs, often regardless of the distance.

In human language: present routing apps have a fixed table where they 
will let you transfer between stops of different names, e.g. to transfer 
from "City, Railway Station" bus stop, to the actual railway station. Or 
between two bus stops which are common transfer points, but have 
different names. Present-day software does allow the calculation of 
alternative routes with a walk *to* the first stop and *from* the last 
stop, but it have a problem with walk-bus-*walk between any two 
stops*-bus-walk solutions. Those are normally (daytime, weekday) not 
important, but often critical when bus service is less frequent: night 
time, low density areas, etc. If I understand the problem correctly, 
such approach comes from the times when routing apps did not have the 
geographical location of bus stops, instead they created a virtual mesh, 
where transfer nodes had to be defined separately. I understand stop 
areas to be those nodes - but we are in 21st century, we have all the 
necessary info to calculate what we need, instead of defining it by humans.

> The definitions of stopareas need to be created by
> those who have a functional need for them

Possibly without the regard of the human of teaching beginners how to do 
it.

> - they are not arbitrary -
And that's another point against them: how is a transfer place marked by 
a user better than a calculated pair of bus stops? Do I really have to 
transfer where *you* want me to?


Greetings,

-- 
Best regards, mit freundlichen Grüssen, meilleurs sentiments, Pozdrowienia,

Michał Borsuk




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