Re: travel_data

Adam

Each planning organization uses one of a small number of software
platforms for doing travel modeling (e.g. emme/2, transcad, vissum,
cube), and then develops their own model in that platform. So each
model is virtually unique and requires interfacing not only to the
software (all of these are proprietary unfortunately), but also to the
particular data that is needed by the travel model and produced by it.
You should inquire with your local planning agencies to find out what
they are using.

There has been considerable interest in developing an open source travel
model, possibly in the OPUS framework. Eric Miller is working on one in
Toronto that I hope will meet this description, Kai Nagel and others are
working on a Microsimulation travel model system (which is probably too
computationally expensive for regional applications over 30 year
horizons, but that is open to discussion), Ram Pendyala is working with
us on a proposal to connect the AMOS activity-based travel model to
UrbanSim, and there may be other initiatives also. We're certainly
interested in collaborating with anyone who wants to contribute to this.

Paul

Adam Rae wrote:
> Thanks Paul,
> I'm also interested to know the name of the travel model you used for
> this process, and was wondering if we might be able to adapt this model
> for use with the data that we've collected. Is this model used
> specifically for travel time data, or does it produce any data that
> might be used in other urbansim input tables? If it is specifically for
> travel times, what inputs would most likely need to be used, and are
> there other models that you use for different purposes?
>
> Cheers,
> Adam.
>
> -----Original Message-----
> From: Paul Waddell [mailto:pwaddell_at_u.washington.edu]
> Sent: Wednesday, 30 May 2007 4:59 PM
> To: Adam Rae
> Cc: Users_at_urbansim.org
> Subject: Re: travel_data
>
> Adam
>
> UrbanSim is generally connected to an existing regional travel model,
> from which either composite utilities from the mode choice model (aka
> logsums) or more generally, congested travel times by mode for the
> home-based-work purpose in the a.m. peak period (or other similar
> measures) are extracted for each travel model year. The connections can
> be automated - we have done this with emme/2 and transcad most recently,
> and previously with TP+ and Minutp. It essentially requires an
> interface to be written for whichever travel model you are using, to
> summarize UrbanSim output and generate the inputs required for the
> travel model; and in the other direction, to extract travel model
> outputs and generate the travel_data table -- with whatever travel
> measures you want to use. Logsums are by no means required, and we have
> found them to be somewhat unstable in practice (though they look good in
> theory) - with small changes in the travel model causing large shifts in
> the logsum measures and therefore precipitating a recalibration of
> UrbanSim.
>
> Paul
>
> Adam Rae wrote:
>
>> I am curious as to what method might be used to obtain the figures
>> under the 'logsum' fields in the travel_data table?
>> If anyone could inform me about how they generated these figures when
>> they were filling in this table it would be greatly appreciated.
>> Thanks,
>> Adam.
>> ----------------------------------------------------------------------
>> --
>>
>> _______________________________________________
>> Users mailing list
>> Users_at_urbansim.org
>> http://www.urbansim.org/mailman/listinfo/users
>>
>>
> _______________________________________________
> Users mailing list
> Users_at_urbansim.org
> http://www.urbansim.org/mailman/listinfo/users
>
Received on Wed May 30 2007 - 17:23:38 PDT