Measuring Transit-Accessibility with Graphserver

[GraemeBrown]

Hi All,

Thought some of you might be interested in an application of
Graphserver. I am using it to develop a measure of transit-
accessibility in Metro Vancouver, where I work as a transportation
planner for TransLink, the regional transit agency.

I have put up a poster describing the measure here:
http://graemebrown.ca/files/Transitibility/MetroVancouverTransitibility.pdf
Please feel free to get in touch if you have any comments or
questions.

By the way, TransLink is not currently using this measure for planning
purposes. It is just proof-of-concept for now, and its applicability
to projects/decision-making is yet to be determined.

Graeme

[Brandon Martin-Anderson]

That's _lovely_.

As a minor aside: it's important to note that the transfer penalty
penalizes the _utility_ of the state at a particular vertex, but does
not actually advance the time associated with the state at a
particular vertex.

-B

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[kkumbada]

Hello Graeme,

I found your application pretty interesting. I'd like to use the
Graphserver to measure an accessibility, too. Before diving into the
world, I'd like to ask some questions to find out the capacity of the
Graphserver. It seems that you are a right person to ask. Here are my
questions:

the nature of output of the server: is that a pure "image"? Or, there
are attributes associated with it? For instance, can i extract the
coordinates of the start and end points and other transit information
of each segment of the output?

the nature of your measure of accessibility: is that network distance?
Or, the numbers of places?

Thank you in advance, Graeme.

On Dec 5 2010, 5:59 pm, GraemeBrown <graeme.a.br...@gmail.com> wrote:
> Hi All,
>
> Thought some of you might be interested in an application of
> Graphserver. I am using it to develop a measure of transit-
> accessibility in Metro Vancouver, where I work as a transportation
> planner for TransLink, the regional transit agency.
>

> I have put up a poster describing the measure here:http://graemebrown.ca/files/Transitibility/MetroVancouverTransitibili...

[GraemeBrown]

kkumbada,

Graphserver is really just the brains behind the accessibility
measure. Its inputs are a pedestrian/cycle network and transit network
and schedule. Theoretically, these inputs could be derived from any
format, but Graphserver comes with tools that make it easy to import
Open Street Map data (for the pedestrian/cycle network), and Google
Transit Feed Spec data (for the transit network and schedule).
Graphserver's outputs are trip-plans in text format, just like you
might find on a transit agency's website. Graphserver can also output
text describing the travel time from a given point to all other points
in the network. I used the latter functionality as an input to the
accessibility map. So, graphserver has no built-in visualization
functionality.

I measured accessibility quite crudely. It's simply a measure of the
"usefulness" of each location, weighted by the travel time to access
each location. In other words, if a given point has quick access to
many useful locations, it receives a high accessibility score.
Usefulness was estimated (again, crudely) as the weighted sum of
population and employment available at a destination, with one job
being considered more useful than one resident.

I'm afraid that we're veering away from the intended subject matter
for this forum - please feel free to email me directly if you have any
further questions. I'd be interested to know more about your project!

Graeme

[Patrick Sunter]

Hi Graeme - realise this thread is pretty old, but I'm in the early stages of a new research project into public transport network quality here in Melbourne, Australia with some collaborators and am interested in Graphserver's potential capabilities for this kind of work, as compared to OpenTripPlanner.

It seems your poster is no longer available on the web? Is there a way to contact you for further info about the tools used etc for this? I'm on twitter @PatSunter, or you can shoot me a mail to patdevelop AT gmail.com

cheers, Patrick.

[Oscar Bolaños]

Hi,

Is there a way to get as well the poster? please mail it to orbolanos AT gmail.com

I'm interesting in doing a similar analysis in my country.

Thanks!

- O.