From our passenger survey on the TransWilts last October, I was really interested to look at the LENGTH of people's journeys - whether they were travelling just a short distance or a long way. So I wrote myself a tool to analyse the data and draw the diagram.
The buttons let you turn the lines on and off (on the live tool, not on the forum I'm afraid) ... but showing on this sample
* Red line - length of THROUGH journeys (for example Salisbury to Kemble)
* Magenta line - length of journeys to and from WESTBURY
* Yellow line - length of journeys to and from MELKSHAM
* Purple line - length of journeys to and from CHIPPENHAM
The horizontal grids are at 80 km (50 mile) intervals; the vertical scale is marked off in percentage of numbers of journeys, and the lines show are cumulative.
I'm not surprised to find longer journeys from Melksham than from Westbury - up to about 80 miles - as estuary passengers have an excellent choice of direct long distance trains, whereas Melksham people need to change. The Chippenham curve IS a bit of a surprise - it shows a considerable traffic headed away from the main line (where an
HST▸ rather than a TransWilts service would have been chosen) ... and looking at the data there seems to be a considerable thitherto-unnoticed (?) flow between Chippenham and the Solent area.
Does anyone else have studies / graphs like this for their areas / lines??
P.S. If you want to see the source code for the tool - it's available at http://www.wellho.net/resources/ex.php?item=t050/distance_graph as it's also served as a "how to" on this week's course 
Click on the map to explore geographics
