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Archive for December, 2015

Cycle commuting analysis of Bristol

Saturday, December 19th, 2015

We love it when our API comes in useful for academic purposes. This is a guest post by Richard Thomas.


Average time to cycle commute

Bristol: Typical cycle commute time

For my MSc dissertation, I investigated determinants of the proportion of people who choose to cycle for their daily commute. Specifically, I wanted to see whether an analysis of realistic cycling routes of a representatively large sample of a city’s population could give improved predictors over existing models.

From 2011 Census data, I extracted commuting origin/destination data for everyone in the Bristol built-up area in its most detailed form of aggregation (typically accurate to within 500m). I wanted to generate plausible cycling routes for these commutes, then for each of these routes to evaluate metrics (distance, hills, cycle paths, traffic). As census data is available giving the proportion of commuters living in each small area who cycle, multi-variate correlation could then be used to estimate the influence of these routing metrics, together with other known influential population measures taken from the census.

So how best to perform this cycle routing and evaluate suitable metrics? On both these counts the CycleStreets Journey Planner API proved invaluable (and made my MSc dissertation a feasible proposition!) I had considered using an existing open source routing engine (such as pgRouting or Graphhopper) operating on an extract of the OpenStreetMap database as this would allow me to directly query tags on each node of a route. However the complexity in interpreting OpenStreetMap cycle-related tags is quite daunting (as documented here on CycleStreets.net).

Because the API returned not just the route, but details of routed distance, duration, “quietness”, estimated calories required and spot heights, useful metrics could be derived quickly from the JSON data using just Python scripts. It would have been good to more directly quantify dedicated cycle infrastructure along routes: although the “quietness” measure included this, it also included road traffic expectations. Given more time, this could have been done by using the actual route coordinates to interrogate the OpenStreetMap or CycleStreets databases, though this was complicated by API-returned points being only in latitude/longitude format rather than database node/segment numbers. In order to limit the amount of data to be processed (and the load on the CycleStreets API server, routing was limited to the 4 most popular routes from each area, although this still required nearly 16,000 routes to be generated and analyzed!


Summed routes (detail)

Summed cycle commute routes (Overview)

The most notable results of these new routing-based metrics (i.e. beyond the key predictor of crow-fly distance) were as follows:

  • Directness (Crow-fly / Routed Distance): strong indication that cycling was less popular if a reasonable (“balanced”) cycling route was particularly circuitous.
  • Max Height Increase (Maximum of sum of all hill climbs for outward or return direction): strong indication (as might be expected) that hills were a strong detractor. This metric was only developed after the MSc was completed; interestingly, in the MSc analysis, the related metric of Effort Ratio (calories / distance) was not a statistically significant indicator.
  • Traffic Exposure (Inverse of “Quietness”): Although this metric visually gives a good indication of cycling routes along busy roads and/or away from dedicated cycle infrastructure it was not a statistically significant predictor of cycling. Although not conclusive, this supports other research showing that cyclists are more sensitive to time taken than to pleasantness or safety when it concerns their daily commute (priorities may be different for a leisure ride).

Summed routes (street level detail)

Street level detail (OpenCycleMap)

 

More details of the analysis are available in the full dissertation (or short synopsis). Detailed 2011 census origin/destination data (table WF02 for OA/WZ) was only made available after the end of my MSc (and then only to academics for specific projects). Thus for the MSc, synthetic data was generated based on (publicly available) census data. However, a later reworking of the full analysis using the new WF02 census data gave very similar results showing that lack of public access to detailed statistics need not be a serious impediment to analysis.

Beyond the key MSc analysis, an interesting spin-off of all the cycle routing was the development of maps (see right and below) that sums the 4 most popular commute routes from the centroid of each census Output Area, giving a good indication of the number of cyclists along individual streets if all these people were to commute by bicycle.

Thanks again to CycleStreets for making the API available to enable this research project. Data processing was done in Python and SPSS with additional processing and map rendering in the open source QGIS package.

Richard Thomas

Editor’s note: We now have a batch routing system available which we’re keen to encourage for academic use like this. It can handle millions of combinations happily – not just the 16,000 combinations noted above!

New features added to Cyclescape

Wednesday, December 16th, 2015

Lots of new features have been added to Cyclescape, our toolkit for cycling advocacy groups.

Our developer, Nikolai, has been busy, working on piles of improvements and bugfixes.

As featured on the Cyclescape blog, the latest updates include:

Street View message replies: While it’s of course possible to navigate off-site, get a Street View link, and return, we’ve taken out that extra stage. The Street View button also tries to find a sensible default location. In a thread, just click on Street View in the reply box, position the map where you want, add a comment and press submit.

Privacy improvements:  Some groups have told us that it is important to them that they are able to operate on the basis of member discussions using real names, so that members know who they are talking to. However, we recognise that this could be in conflict with the entirely reasonable desire not to have one’s name on the public internet if wished. Accordingly, we have worked to implement a solution to this, whereby you can set your real name which people in your groups will see, but set a display name for everyone else. Previously the display name was always used.

Improvements for groups: If you didn’t already know, cycling groups are able to create their own Cyclescape space, giving a custom web address and various personalisations. You can now create a group using the ‘Request new group’ form in the top-right of the groups gallery. Groups can now add a photo to help personalise their page, alongside information about the group.

Search system overhauled to give much better results: We’ve replaced the search result system with a completely new engine that gives much better results. After a week of tuning the results, we think this now seems to find what you’re looking for pretty consistently. Secondly, we’ve added pagination, so you’re no longer limited to one page of results. Another long-awaited improvement is that searches within a group’s area will only return results from that area. So if you’re in, say, Camden Cyclists’ Cyclescape area, you won’t get results polluted with issues from Cambridge, Sheffield, Leeds, or wherever.

Getting discussions by e-mail now better: Did you know that you can also get Cyclescape discussions by e-mail? In fact, Cyclescape can be used like lots of mini e-mail lists, which you can choose to subscribe/unsubscribe to on a per-thread basis. We’ve made a number of improvements. Firstly, you can now enable digests, so you can read what’s happening by getting a single e-mail a day. Next, e-mails are now properly threaded. Also, we’ve added deadline reminders, so you’ll get a reminder a day or two before a date in a thread you’re subscribed to. So fewer excuses for missing deadlines now! A further improvement is that new users, and users newly-subscribed to a group, now receive a welcome e-mail to confirm each of these.

Deadline management improvements: In case you didn’t know, your ‘My Cyclescape’ page has a listing of all the deadlines/dates in the threads you are subscribed to. So it’s easy to get an overview of what’s coming up. We’ve added an iCal feed, so that if you use a calendaring system like Apple Calendar, Google Calendar, Outlook, etc., you can have these events appear automatically in your calendar. Also, if you have e-mail enabled, each deadline/date e-mail will now include an iCal attachment for that deadline/date. Another improvement is that you can now specify a time, rather than purely just a day, when replying in a thread.

We welcome your feedback, especially to report bugs or give us route feedback.

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