I’ll start this with the standard “I’m not a lawyer”.
We need to consider there are different definitions of “road” used in OSM, common-british-english, and legal-british-english.
Here, we’re dealing with legislation and Legal English. The definition for road that concerns us comes from the Road Traffic Act 1988. This has a much broader definition that many realise.
A legislative road is any way that that the public have access along, either as a right, permissive access, or “tolerated trespass”. If there is any clear and reasonable signage that refuses access, or makes access to conditional, to ALL forms of travel, then the road is not a Legislative Road.
This means a 1m wide muddy path across a field which public have permissive access on foot, is a road under the RTA 1988.
If a motor vehicle uses any legislative road, then laws affecting legislative roads apply.
In this discussion the legislation in question is the “Road Traffic Regulation Act 1984” which provide speed limit rules for motor vehicles.
All legislative roads have Speed Limit rules. It does not matter if the road is public owned, privately owned, or a 1m wide muddy path. The definition is based on whether the public have at least “tolerated trespass”
The starting point for Speed Limits are National Speed Limits. These are default and created by the structure of the road
The appropriate authority (highway authority) can change the speed limits via traffic orders. And must put up signage for most of the speed limit laws to be enforceable.
For private roads with at least “tolerated trespass” the national speed limits apply for motor vehicles, but a since Highways Authority has not put up required signage, the speed limit which exists cannot be enforced. Unless it is a NSL Restricted Limit.
If a privately owned road give access to pedestrians, but has signs clearly making access conditional for motor vehicles things get complicated. It is still a legislative road since public can access (pedestrian, cyclist), but motor vehicles would be trespassing if they break the rules giving access (5mph speed limit) and breaking national laws if driving above NSL and it was enforceable.
So I suggest the maxspeed tag
- must be used on unadopted roads with public access which have lighting, or correct signage in place
- must be used for privately owned roads that are public access through roads
- should be used for privately owned roads which have public access, but have speeds limit signs making access conditional (permissive)