OSSTIP/WP6: Difference between revisions

WP Essentials

This is a Work Package as part of the OSSTIP project.

Inputs:

• Relevant GTFS files for region of interest (Melbourne) See (OSSTIP/WP1).
• A design of output format for network topology information, to know what to convert the GTFS line information into for further use and modification (necessary to create new timetable). Developed in OSSTIP/WP5

Outputs:

• New scripts committed into OSSTIP repository to allow extracting relevant information from a GTFS file.
• Documentation on how to use these, sample results.

Estimated Time: Medium

Status: WP created in Sep 2014 during PTUA Action-case. As of 2014-11-05 :- timetable and frequency modification capability working, now working on line-extension capability.

Requirements Summary

Motivated by PTUA project wanting to extend several train lines, and increase frequency along several existing bus and tram lines.

As compared to SimpleGTFSCreator previous capability to create new bus lines based on a GIS network representation OSSTIP/WP5 and several scripts :-

In this case, since modifying existing lines, we need to add several new steps to the workflow. The workflow effectively will become:-

Stage 1) add ability to read info for selected lines out of a GTFS file and:-

• Save info re average headway (minutes between vehicle visits at stop) at different periods of the day.
• Similarly, calculate and save info on average speeds on route sections during different periods of the day.

We then need to give users tools to modify these speeds and frequencies in a convenient way.

• I.E. Based on an input GTFS, copy some lines across directly, versus others should be re-written (based on new specification), and some scrapped.
• (Or a minimal 'quick' version of this is just to create entirely new GTFS for new lines, and a 'subset' of old GTFS with some of old lines.

Finally, we need to updgrade the Also need to modify the SimpleGTFSCreator on 'output' end to create a new GTFS timetable, based on this more advanced speed and frequency specification per-route.

Use-Cases

(Developed during work with the PTUA - see OSSTIP/WPPTUA1, OSSTIP/WPPTUA2, OSSTIP/WPPTUA3.)

So this means, the inital process for creating a modified timetable is:

• Save the 'Nominal basic full-stop timetable' stop order.
• Convert this to a GIS file if necessary, including line segments.
• (write extra script to) Save speeds between these stops.

Then:

• (a) for extended lines:
  • a script to nominate the extension, and the connecting stop to the original line, then create a segmented version of extended line.
  • Then manually fill in appropriate speeds for the extended segments, based on the existing segments.
• (b) for updated freq. or speed lines:
  • Just need to either (1) update the nominal line frequencies by a certain factor, or (2) write a script to increase avg speed, and thus reduce between-segment travel time, by a certain factor.

(Note:- for both of the above, implies ability to specify a "Per-line" frequency chart for my SimpleGTFSCreator script, rather than a global one.)

(Note2:- is there a need to try and also do some post-processing to 'smooth' arrival frequencies on multi-route sections sharing same track sections? This is probably a 'nice to have' post-optimisation).

And last stage:

• Use my "SimpleGTFSCreator" script to create a new timetable based on these chosen modified lines.
• Need a final script to then "Paste" this in together with a GTFS of several other regular non-extended lines from a previous timetable.

Results

TODO.