Basic routing with OS Open Data and QGIS

Drivetime analysis

Drivetime analysis is a tool used to determine which locations are accessible from a point within a certain time or distance based on a road network.

Road Networks

Ordnance Survey has a number of road network products of different levels of detail:

Product	Complexity	Availability	Description
OS MasterMap Highways Network – Roads	High Complexity	Premium	A topologically structured link and node representation of GB's road network
OS MasterMap Highways Network – Routing and Asset Management (RAMI)	Most Complex	Premium	The content of Roads with additional information on the management of roads as an asset and routing information
OS Open Roads	Lower Complexity	Open	An open high-level view of GB's road network
OS NGD Transport Network	High Complexity	Available under the PSGA	The OS NGD equivalent of our topological road network
OS NGD Routing and Asset Management	Most Complex	Available under the PSGA	The OS NGD equivalent of our additional RAMI data

OS Open Roads

We will use OS Open Roads for the road network drive time analysis.

OS Open Roads is our free, high-level road network dataset and is our simplest representation of Great Britain’s roads.

Processing

• Download OS Open Roads from the OS Data Hub.

• Select the GeoPackage file format for this analysis

• Extract the GPKG file and load into QGIS.

• Open Roads contains three feature types: Motorway Junction, RoadLink and RoadNode

Optional - To reduce the processing time of the next steps consider clipping the road_link layer to your area of interest (AOI)

Adding Simple Road Speeds

• Check Create a new field

• Input speed_kph to name new field

• Copy and paste the below code into the expression tab

CASE 
WHEN "road_classification" = 'A Road' THEN 56
WHEN "road_classification" = 'B Road' THEN 48
WHEN "road_classification" = 'Motorway' THEN 112
else 32 END

Routing

QGIS has a built in Network Analysis tools such as service area and shortest path. However, for a visually clearer output we will be using a plugin called QNEAT3

Select the QNEAT3 Toolbox from the toolbox panel and select Iso-Area as Polygons

Fill in the pop up box as shown here:

Visualising the output

In the Layer Properties window under the Symbology tab:

• Select 'Categorized'

• In the value field select '1.2 cost_level

• Select a suitable Color ramp

• Change the fill for 'all other values' to transparent

Add a base map of your choice, we have used the OS Maps API here:

Benefits

• Simple drivetime analysis

• All open-source data and software

• Visualisation of distributions and hard to access areas

• Overview of how accessible your services are

• Identify areas for more detailed study