November Visualisation: Contour on a Road Network and Census Accessibility Data

November Visualisation: Contour on a Road Network and Census Accessibility Data

November Visualisation: Contour on a Road Network and Census Accessibility Data

You might have noticed how Guildford-centric our maps can be – it’s not because Guildford has a particularly interesting road network. Simply that we have big enough egos that we like to put our office on the map.

This November blog being no different, here’s a map of Guildford.

Normally when showing journey time accessibility using census data there is a corresponding table or dataset to show the sum or % of the population who can reach the designated destination within the allotted time ranges.

This month we are giving you a double whammy, a 2in1, a BOGOF, if you will.

Typically, our contours cover an area of land that would be accessible within the different time ranges, this month we used those ranges to create boundaries of colour on the road network itself. Overlaying the road network are points, the colour of which indicates the number of people who live in the immediate vicinity of that road link.

So how did we do it?

Starting with a public transport calculation, we found the travel time to the commercial area in Guildford. Once the TRACC calculation was complete, we exported these results into QGIS. The travel time data has been classified into three ranges of 10 minutes each, which would typically have been used as the basis of the contour, instead we merged the contour data to the road network data to display road networks classified based on the contour data. To keep the visualisation focused we only included data from A and B roads.

In addition to this, we used census data to establish how many people would have access to each link. This population data is represented by points on the road links, classified in three ranges: 0-100, 100-300 and 300+ (with a maximum of 693 people).

So here it is, all of the possible information you could want on the amount of people who can get to Guildford town centre, all on one map.


Stay tuned for our last visualisation blog of the year, where we are looking at census data and commuting times – yes I understand your commute right now is from your bed to your dining table or home office.

Keziah is the Digital Marketing Executive at Basemap Ltd. She has almost 2 years experience in the digital realm after graduating from the University of Plymouth with a BA in Illustration and a MA in Publishing.