Modelling individual level routes and CO2 emissions for home to school

We have recently published a paper in the Journal of Transport and Health where we modelled the impact on CO2 emissions of an increased uptake of active travel for the home to school commute. The paper is freely available to anyone under Gold Open Access, with a CC-BY Attribution license.

One of the challenges in this paper, building upon (Singleton, 2014) was being able to model individual routes from home to school for all ~7.5 million school children in England. In addition to origin and destination locations, we also know what modes of travel are typically used to get to school, thanks to the School Census (also known as the National Pupil Database). While modelling a small number of routes is relatively straight forward to perform within a GIS, the challenge was to complete the routing for all 7.5 million records in the data set.

To calculate the route, we used a combination of two different pieces of software – Routino and pgRouting. Routino allows us to use OpenStreetMap data to derive a road-based route from given start and end points, using a number of different profiles for either car, walking, cycling or bus. The profile used is important, as it allows the software to take into account one-way streets (i.e. not applicable to walking, but applicable to driving), footpaths (i.e. applicable to walking only), cycle lanes, bus lanes, etc.. The screenshot below shows an example route, calculated by Routino.

Screenshot of routing within Routino

Example of the route calculated using Routino for a car travelling from Rosslyn Street (1) to Granby Street (2). © OpenStreetMap contributors,

For railway, tram or tube travel, this was implemented using pgRouting from both Ordnance Survey and edited OSM data. The different networks were read into the PostgreSQL database, and routes calculated using the Shortest Path Dijkstra algorithm. This returned a distance for the route, which was stored alongside the original data.

Routino and pgRouting were called using R, which also managed the large amounts of data, subsequently calculated the CO2 emissions model, and created graphical outputs (see below).

Map of CO2 emissions (grouped by residence LSOA) for Norfolk.

Map of CO2 emissions (grouped by residence LSOA) for Norfolk.

To run the routing for each pupil for four years worth of data (we had data from 2007/8-2010/11, although we only used data from academic year 2010-2011 in the paper) took about 14 days on my 27″ iMac. We considered using a cloud solution to shorten the run times, but given we were using sensitive data this was deemed too problematic (see related blog post from Alex on this). This work highlights that it is possible to perform some types of big data analysis using a standard desktop computer, which allows us to perform this type of analysis on sensitive data without needing to make use of cloud or remote processing services, which are often not compatible with restrictions on sensitive data.

*As you would expect, the postcode unit is sensitive data and we had to apply to the Department of Education to use this data. Any postcodes or locations used in this blog post will be examples – e.g. L69 7ZQ is the postcode for my office!

Singleton, A. 2014. “A GIS Approach to Modelling CO2 Emissions Associated with the Pupil-School Commute.” International Journal of Geographical Information Science 28 (2): 256–73. doi:10.1080/13658816.2013.832765.

Cross-posted from

Introduction to QGIS: Understanding and Presenting Spatial Data

On Monday 17th November, I ran a day course on Spatial Data and QGIS with 15 participants. We had people from a wide range of backgrounds and interests, including geology, politics, health and many other disciplines. We looked at some of the theory behind GIS, such as projections and coordinate systems, as well as practical elements on how to use QGIS. I managed to get QGIS version 2.6 (Brighton) installed on the University systems, which only came out towards the end of October, so it was great that the participants could see and use the latest version. We also looked at the process of classifying data for cholopleth maps, including the important decisions to make when selecting colours, number of classes and method of classification.

I’ve attached the materials I used to this blog post (see below). I took the decision to make my material available under the Creative Commons Attribution-ShareAlike 4.0 International License (see for details), which means that the material I created for this training session is free for anyone to use, as long as you attribute the material to me, and make any material you derive from this available under the same license. I would also ask you to let me know when you use my material, as it’s useful for me to know how many people are using it, and what sort of courses they are using it for.

In this form, some of the resources will be more useful than others, but I hope they are helpful. Any comments are gratefully received, either via email, or through  comments below.

Happy GISing!



‘Hearing In’: Philosophical perspectives on sonification

I was invited to attend ‘Hearing In’ on Friday 10th October, a workshop organised by the Centre for the Study of the Senses, Institute of Philosophy, University of London. I was speaking about my work on sonification, alongside Chris Chafe (Stanford, US) and Paul Vickers (Northumbria, UK) and the aim of the workshop was to examine some of the theoretical challenges raised by sonification, and to explore the relevance of specific examples for our philosophical understanding of auditory and music perception. (Download programme, PDF, 53KB).

Chris Chafe showed us a wide variety of examples from his work as a musician, composing sonifications in collaboration with scientists and engineers. One of the areas he is interested in is whether a computer can be programmed to create human sounding music, with the hope this can aid our understanding of the creation of music. He also showed a range of installations, including a sonification of the ripening process of tomatoes and the tides.

My presentation was of my PhD work on sonification, evaluating ways of using sound to represent spatial data. I am very interested in how we combine sound with vision to represent additional spatial data, rather than using sound as a replacement for visual display of spatial data. The presentation is available below, and includes my PhD work with specific reference to my second case study on the UKCP09 (UK Climate Projections 2009) data set and how we could use sound to represent the uncertainty within this data set. I also discussed the conceptual model I have developed based on the results of my PhD, which is currently under consideration for publication. (Download presentation with multimedia, PowerPoint, 50MB).

Paul Vickers presented his work on the theory of sonification, considering how sonification compares with visualisation as a way of representing data. He adopted an approach of considering the semantics of the terms involved, highlighting the importance of the intent of the sonification designer and whether they wish the sonification to be a form of data communication, or a piece of work in itself (for example, as an art installation).

After each presentation and at the end of the workshop we had a wide ranging discussion of the issues mentioned by the presenters. It highlighted to me how much there is still to be done in understanding the theoretical side of sonification, including things such as the specific definition of what a sonification is, what it is not, and what the differences are between sonification and music. I believe Chris, Paul and I gave a fair overview of sonification to the Philosophy community, and that this is the beginning of a fruitful relationship between our communities.

Many thanks to Ophelia Deory for organising this event, to Barry Smith, Matthew Nudds and Emily Caddick for providing comments on our presentations, and to all the attendees to the workshop for providing a interesting and through provoking discussion.

INLT Writing Retreat

View of Juniper Hall from Box Hill

Last weekend I attended the INLT Writing Retreat, at the Juniper Hall Field Centre set in “an unspoilt area of the chalk North Downs”. The INLT (International Network for Learning and Teaching in Geography) is a group of geographers who want to improve the quality and status of learning and teaching of geography in higher education internationally, and every couple of years or so, get together for a writing retreat. 

I’d never been on a writing retreat before, and I really had no idea what to expect. In fact, I may not have even attended if it wasn’t for a HEA GEES workshop in Manchester on 23rd May where Helen Walkington plugged the INLT writing retreat workshop.

Once signed up, we did some work on our group topic (GIS Learning, spatial literacy and spatial citizenship) beforehand and laid out a few ideas. However it wasn’t until we were in the room together that the ideas for our JGHE paper started flowing. A mixture of writing group sessions and sessions with everyone enabled us to develop our ideas, get some very useful feedback, refine the ideas, collect some data, and do some data discussion all in a day and a half!

It was an amazing experience and I would recommend attending a writing retreat for anyone who wants to get their teeth into a discussion in their area, and get to meet some of the big names in their field.

Also posted on INLT website at: