Concerned about default value of maxTransfers = 2

[Patrick Sunter]

Hi there,

I've been using OpenTripPlanner as part of a research project to propose improvements to Melbourne, Australia's public transport network - and its shaping up really well so far.

A concern that arose today though from a transport planning perspective :- it appears the default value of maxTransfers=2 in the RoutingRequest class ?? I discovered this when doing some batch analyst tests and it was giving a -1 trip time value for several trips until I increased this parameter.

As a public transport-oriented researcher and advocate for sustainable transport I'm just a bit concerned with having a max transfer this low by default.

The reason is that a strong theme of research into transport best-practice in recent years is that for transit to compete with the car in terms of coverage, we need to plan entire networks that _do_ sometimes require several transfers to access all of a large urban region - but the transfer times should be minimised using pulse timetables or high-frequency services. See e.g. http://www.newsouthbooks.com.au/books/transport-for-suburbia_beyond-the-automobile-age/ or http://www.humantransit.org/2009/04/why-transferring-is-good-for-you-and-good-for-your-city.html

So could I suggest at least 3 as the default?? What do other users think?

I know its just a value that can be overridden in the application-context.xml :- but in my experience as a developer and scientist in computational modelling, default parameter values really do matter ;)

cheers, Patrick Sunter.

[Stefan Steiniger]

Hi,

I assume 2 transfers means transfers among 3 trams/buses/trains?
Living in a big city (Santiago) I try to take at max 2 different
trams/buses/trains. But I am living fairly central (access to trunk
transport/metro - no need for a feeder transport). So, I am a split
about this request when considering travel advises.

However, for an analysis with Batch Analyst this may make sense.

my 2 cents,
stefan

Am 28.08.13 10:21, schrieb Patrick Sunter:

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[Patrick Sunter]

On Thu, Aug 29, 2013 at 12:40 AM, Stefan Steiniger <sst...@geo.uzh.ch> wrote:

Hi,

I assume 2 transfers means transfers among 3 trams/buses/trains?

Yes that's correct from my reading of the code and tests Stefan.

 

Living in a big city (Santiago) I try to take at max 2 different trams/buses/trains. But I am living fairly central (access to trunk transport/metro - no need for a feeder transport). So, I am a split about this request when considering travel advises.

However, for an analysis with Batch Analyst this may make sense.

Yes :- I think 2 within the main system is pretty reasonable, but if you were to take a feeder minibus at both the start and end ...

thx, Patrick.

 

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[jorden...@goabout.com]

Yes, the value of 2 seems too low. We changed this value to 10 for the long distance service, but 2 might not even be a good default for the retrying path service.

 

Who knows what the reasoning behind the current default is?

 

Jorden

[Matt Conway]

I'm not sure exactly, but IIRC we had a conversation about this a while back and the number was just made up. I think it's more to prevent super-long computation times than to limit transfers. I suspect most users would rather see a four-transfer trip than no trip at all. Things like preventing unnecessary transfers are generally better done with weighting than hard limits.

TL;DR version: I'm in favor of increasing this limit.

Matt

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