Main Roads and Railways Map

What the map shows

Every cell of about 10 metres holds one of seven classes: motorways and trunk roads, A roads, B roads, tertiary and minor roads, and heavy, medium, and light and heritage railways. Close in, each is drawn in its own colour, as the key shows. Any cell a road or railway crosses at all takes its class, so each is an unbroken line of cells however it runs, and where two cross in one cell the worse hazard is kept: a motorway over a railway, a railway over a B road. Slip roads count as their road, and the minor roads and lanes between villages and farms (OpenStreetMap's unclassified roads) count with tertiary roads. Anything in a tunnel is left out, and so are town side streets, driveways, car parks and farm tracks.

Zoomed out, a pixel covers far more ground than one cell, so zoomed out every road and railway is drawn in one amber, its strength showing how much of the pixel it fills; a pixel with any in it keeps a clear line of colour, so they stay in view as you zoom out.

Where the data comes from

The roads and railways come from OpenStreetMap, the open map of the world, through the regional extracts Geofabrik publish. Main roads and railway lines are among the most completely mapped things in OpenStreetMap almost everywhere, so this layer is close to complete worldwide. The database currently covers United Kingdom, Europe, North America, Australia & New Zealand and Japan.

Why a rocketry site maps roads and railways

A rocket under a parachute drifts with the wind, and a field that looks well clear of traffic can have a main road or a railway line a few hundred metres downwind. A rocket or parachute coming down on a busy road or a line is a danger to the people on it as well as to the rocket, and recovering one from a carriageway or a railway is worse. Knowing where they are around a launch site shows which way the drift must not go and how short it has to be kept.

The same data is going into the Altimeter Cloud Landing & Radio tool, alongside the water, the trees and the ground, for the chance of a landing on or near a road or railway before anyone flies.

Use the data in your own projects

Everything on this map is available through the free Main Roads & Railways API, no key needed: any square up to 30 km across around a point, every cell as its class in three bits, all seven classes or just those you ask for, uncompressed or packed with zlib or LZMA. The download panel on the map does the same thing from here: put the cross on your site, choose the size and compression, and save the file.

The file uses the same 32 byte header as the water and tree canopy files, with three bits a cell, eight cells to every three bytes. Before compression, near Windermere (54°N):