Either `motorway`, `major_road` (containing `trunk`, `primary`, `secondary` and `tertiary` roads) and `minor_road` (less important roads in the hierarchy like `residential` or `service`) or `path` for
non vehicle paths (such as `cycleway` or `footpath`).
subclass:|
Original value of the [`highway`](http://wiki.openstreetmap.org/wiki/Key:highway) tag. Use this to do more
precise styling.
properties:|
Additional properties describing the nature of road.
The properties `bridge` and `tunnel` can be combined with `oneway` as well. So to style all bridges the same you
should style both the properties `bridge` and `bridge:oneway`.
Properties can be one of `bridge:oneway`, `tunnel:oneway`, `ramp`, `ford`, `bridge`, `tunnel` or`oneway`.