The start point
We use the 'shortest designated route' to determine a child's closest school. We then use that distance in the free transport assessment.
Ordnance Survey uses information from Royal Mail and local councils to make a start point (seed point) for each address. The seed point usually falls within the bounds of a property and is accurate to the nearest 10 centimetres.
The digitised network
Ordnance Survey created the integrated transport network (ITN) and accurately digitised it for mapping.
The ITN measures along the centre of roads and takes corners at right angles. Mapping services like Google Maps use the same information but a less accurate start point. Our mapping is accurate to at least 1 metre and includes public routes such as alleyways, footpaths and bridleways.
The network only includes routes that Ordnance Survey class as 'public'. So that does not include:
- parks with no footpaths
- parks that are not open all the time
- short-cuts across open land without paths
- footpaths across private land.
The end point
The end point is the nearest open school gate to the start point when following the shortest designated route. The gate must be officially available for students to:
- enter at the start of the school day
- exit at the end of the school day.
We have set the location of these school gates, and we consult with schools every year to ensure they are available.
The shortest designated route
An algorithm in our mapping software RouteFinder works out the shortest designated route. RouteFinder measures in kilometres and then converts which is accurate up to 1.609344 metres.
The shortest designated route may not be a driving route because it could be all or part footpaths. It may not be a walking route because we measure roads along their centre and not along the edge.
Measuring with other mapping tools
You may get a different measurement for the shortest designated route if you use a tool such as Google Maps. We cannot consider these measurements because they do not form part of the admissions process.
Addresses outside the digitised network
We use an internet mapping tool for addresses that are more than six miles outside Oxfordshire's boundary.
We use Google Maps for addresses in Europe.
We measure a straight line to the school gate with a longitude and latitude calculator for addresses outside Europe.
Own admission authority schools
A small number of schools that administer their own admissions, use a straight line measurement from home to school. We calculate the distances for those shoes.