User:Jamicu/UK Speed Limits

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A page for storing info I've gathered about UK Speed Limits, starting from May 2012.
I gathered a lot of data during summer 2011 but didn't think to save documents or bookmark links, so I thought that in future I'd should note it down somewhere

Please Note: The following are my notes


It's been compiled by researching official documents, legislation and case law. I've regularly noted advice in motoring discussion forums, but then went on to confirm by checking official legislation or case law. The following may contains errors due to the stupidly complicated nature of British Speed Limit legislation, but I'm fairly confident the following is a reliable guide to UK speed limits. The problems are down to decades of small changes leading to a vast array of legislation updates and guidance. It think it's reasonable to argue that the array of existing legislation and guidance is now complete mess and needs to be brought together in on single new piece of legislation and guidance.

Its also common to hear people in the UK referring to a book called The Highway Code. This book is a simplified guidance leaflet, and has limited use when trying to work out the details of UK Speed Limits. The book is not legislation.

What is a Road that results in a Speed Limit (for the UK)?

In the UK default speed limits are defined by the physical features of a road, and not signs. Where the physical features of a road result in a speed limit deemed unacceptable a local authority can create a local speed limit which is indicated using signs.

Legislation defines a road as :

  • Any way, other than a water way
  • Over which the public have right of access by whatever means
  • Whether subject to toll or not
  • And includes the roads verges, and any bridges ( permanent or temporary )
  • Or tunnel through which the road passes

So in the UK, Speed Limit legislation applies to any Way the public have unobstructed access to. If the entrance to the way has a closed barrier/gate then the public is not considered to have access and the way is not a road. It's accepted you have to pay to use some Ways, so if the gate exists only as means to restrict access to those that have paid then the Way is still considered a road. This means Speed Limit legislation applies to many Ways you'd expect it to not apply to. eg Supermarket Car Parks, Private Roads, and narrow overgrown country footpaths.

National Speed Limits are set by the physical features of road, and not signs. Signs exist across the road network because it's been accepted it can be hard to recognise the type of road your driving on, and that it's unfair to prosecute for speeding where a genuine mistake would be reasonably made. Legislation states that the public should be advised, or reminded, of the speed limits by the use of signs that follow a protocol for location and size. Put differently, if you break a speed limit created by the physical nature of a road it is a defence to state you did not know the speed limit, but if prescribed signs are present the defence can not be used.

Recognising a UK road speed limit

Default National Speed Limits(NSL) are defined by the nature of the road and vehicle on the road. A NSL limit is not set by a road sign. In most cases help should be provided to indicate the type of road with prescribed signs at the beginning of single, dual, and restricted NSL roads. (note: If the correct NSL Restricted road sign is missing you can still be prosecuted for speeding)

Local Speed Limits are defined by signs and vehicle on the road. There must be a sign at the beginning of the LSL with reminders along the section of road(s). When the LSL ends a sign indication the start of the new speed limit is needed, with the exception of a Restricted Road.

Several types of roads must have reminder signs (repeater signs) at intervals along the road. eg A nsl_single along a lit road. Unfortunately these reminder signs (repeater signs) can be several hundred meters apart and easily missed when mapping a road.

NSL Restricted Roads have unique signing requirements. This type of NSL road is not obliged to have signs showing the start of the Speed Limit to enable a prosecution, and reminder signs (repeater signs) are banned along the this type of road.

Speed Limit Groups

Special Roads (Motorways, major bridges, and a few very important roads)

The UK has decided that some of it's most important roads and bridges need separate specific legislation which included speed limit rules. These roads are called Special Roads. The vast majority of these special roads are commonly referred to as Motorways and are clearly marked by large blue signs. Other Special Roads include some major bridges and few important roads.

National Speed Limits (NSL)

National Speed Limits are considered to be the default speed limits if a road is not a special road (motorway) or has signs stating a specific local speed limit exists.

The UK has three default National Speed Limits types. They are Dual Carriageway, Restricted Road and Single Carriageway. When you enter into an area of Dual or Single Carriageway roads the start of the first road should have a Nation Speed Limit sign. Signs are controversially not needed to advise the start of a NSL Restricted Road.

Single Carriageway Roads. Any NSL road that does not meet the exact requirements for a Dual Carriageway, or Restricted road is a NSL Single Carriageway.

Dual Carriageways Roads. If a road has oncoming traffic and some form of barrier makes it difficult to drive into the oncoming traffic then the road is a dual carriageway.

  • The 'barrier' can simply consist of grass strip or area of slightly raised ground. Typical motorway barrier not needed. Wide area of paint is not barrier and does not create dual carriageway.
  • A traffic island/crossing point island/short road island does not create a section of Dual Carriageway. Length of barrier that would start a dual carriageway has not yet been clarified with case law.
  • A one way road is not a dual carriageway eg roundabout.
  • There is significant confusion about the situation where Dual Carriageways separate for a while to effectively create two separate roads, or are part of slips roads. The necessary strict interpretation of the law means these fail to meet the Dual Carriageway tests, but it can be argued the intent of the law is present, but meeting the 'intent of the law' is worthless if charged with speeding. I've heard it compared to a computer program that has a bug that requires a patch. The intent of the program is irrelevant cos it will still strictly follow the existing code, until patched.
  • There is a common misconception in the UK that a Dual Carriage requires two lanes to be present on either side of the barrier. It a barrier that creates a Dual Carriageway, not the number of lanes.

Restricted Roads. Its accepted that many Single & Dual Carriageway roads need significant restrictions on speed, especially around busy junctions or in areas where people routinely cross the road. It was decided that need for significant speed restrictions along NSL roads coincides with the need for extended sections of Street Lighting. So where a System of Street Lighting exists the the National Speed Limit is much lower (eg 30 mph for cars)and the road is called a Restricted Road.

  • A System of Street Lighting is considered to be sections of road between at least 3 or more lamps with the distance between lamps no more than 183m. So a couple of lights at a junction, or sharp bend, does not create a Restricted Road. The lighting must also be above approx 4m in height. If under 6m in height spaces must be less than 45m. If the height tests fail the the lighting is considered Footpath Lighting and not Street Lighting.
  • Guidance requires authorities to place signs at the start of Restricted Road (area), but it's only guidance and the penalties for speeding can still be enforced if the signs are not provided. For other road types the Speed Limit would not be enforceable if signs were inadequate. The Street Lighting is considered to be the reminder signs and other reminder signs are banned.
  • The lack of a strict obligation to make the speed limit clear is controversial because the posts of the street lighting can be hidden by trees/shrubs with no evidence of the lighting (at least during the day).
  • It is common to believe NSL Restricted Roads are linked to Urban Areas because the majority of lit roads are in Urban Areas and simplified guidance commonly refers to Restricted Roads as 'Built Up Areas', but Restricted Roads do not necessarily occur in urban areas, so to use 'built up area' to tag restricted roads, should or could, cause confusion.
  • It even more common to believe that Restricted Roads are not NSL roads. NSL Restricted Roads are a type of NSL road.

If a Single or Dual Carriageway requires lighting then the Single or Dual Carriageway status will shown using NSL reminder signs, but these small signs can be hundreds of metres apart and easily missed. This use of NSL signs also misleads because it makes people believe that a Restricted Road is not a type of National Speed Limit road.

Local Speed Limits (LSL)

If a local authority believes the default NSL is not appropriate for a road then the local authority can create a different Local Speed Limit (LSL) following guidance laid down by Department for Transport. LSL's must be shown by large signs at the beginning road, and small reminder signs must be displayed at regular intervals along the road. A local speed limit cannot be made for a road that would otherwise come under the classification of the national speed limit, for example, if a lit road had a 40mph LSL and was to be reduced to 30mph, then the appropriate sections of the road traffic act would be used to revoke the local limit and make the road a NSL road (restricted type).

LSL's for individual roads The speed limits used are commonly ' 20mph, 30 mph, 40 mph, 50 mph and 60 mph. 30mph local speed limit is for roads where no lighting is present. The following is an example in GoogleStreetview near Churston, Torbay an area where it's considered that lighting would impact on the rural setting.

LSL's for zones (or groups or roads) Reminder signs are considered unsightly clutter. In some situations a local authority can give an area (zone) a speed limit. The entrance to the zone must have a sign making clear to the driver that they're entering a speed limit zone, but once inside there is no need for reminder signs. On leaving the zone there will be sign advising the zone has finished.

The most common zone is the '20mph zone' LSL is used for areas of residential roads which are not part of the core transport network. The 20mph zone speed limit is primarily enforced by physically making it difficult to drive faster than 20mph.

Recently the UK Government has started a trial(?) of 40 mph zones. These are expected to be used in rural areas where the Single Carriageway speed limit of 60mph is considered dangerous, but reminder signs are not wanted. For example, the Department of Transport have suggested a 40mph zone might be appropriate for an Area of Outstanding Natural Beauty, where a reduced speed limit might be needed, but where reminders signs would harm the appearance of the area.

Private Roads Limits

Speed Limits legislation applies to all accessible roads regardless of ownership (see section 1). But it is rare that the appropriate Authority will be able or allowed to provide the necessary signs on private land, and therefore in nearly every case the speed limit can not be enforced. It must be remembered that signs are not needed to enforce speed limits on a NSL Restricted Road

Many Private Roads have signs indicating Speed Limits below the those prescribed by legislation (eg 5mph in along a service road). It can be argued that the landowner can attempt to enforce these limits by arguing that travelling in excess of the given speed limit breaks a contract, and or, results in trespass. Therefore in these situations OpenStreetMap should use the Speed Limit set by the landowner?

Speed Limit Table

Basic table of UK speed limits evolved from one on wikipedia but I've noticed that wikipedia and other tables exclude vehicles mentioned in some legislation. I'll try to add these later. (eg Invalid Carriages have speed limits on 20mph on single & dual carriageway roads (but what's an invalid carriage?)). There are also speed limits for mobility scooters.

I'm sure there is a machine readable concept elsewhere on OSM wiki (?) and I'm wondering if the same thing would be of use for speed limits.

The tags used below are not all used in OpenStreetMap

Furthermore, the following speed limit tags can reasonably be argued to be too complicated and unlikely to ever be properly used

United Kingdom - National speed limits by vehicle type and speed limit designation type
UK:sign_private UK:zone_20 UK:zone_40 UK:sign_20 UK:sign_30 UK:sign_40 UK:sign_50 UK:sign_60 UK:nsl_restricted UK:nsl_single UK:nsl_dual UK:motorway
Cars, motorcycles, and

car-based van up to 2 tonnes MLW

 ? 20 mph 40 mph 20 mph 30 mph 40 mph 50 mph 60 mph 30 mph 60 mph 70 mph 70 mph
Buses, coaches, minibuses up to 12m
Goods vehicles up to 7.5 tonnes MLW
 ? 20 mph 40 mph 20 mph 30 mph 40 mph 50 mph 50 mph 30 mph 50 mph 60 mph 70 mph
Towing caravans, trailers, or articulated.

Includes cars, motorcycles, and goods
vehicles up to 7.5 tonnes MLW

 ? 20 mph 40 mph 20 mph 30 mph 40 mph 50 mph 50 mph 30 mph 50 mph 60 mph 60 mph
Goods vehicles over 7.5 tonnes MLW  ? 20 mph 40 mph 20 mph 30 mph 40 mph 40 mph 40 mph 30 mph 40 mph 50 mph 60 mph

Note: UK:sign_60 speed limits for vehicles other than cars is created from experience, due to problems finding a definitive official published document

Notes and oddities

Note 1 - Roundabout along dual carriageway appears not to be part of dual carriageway. Therefore it's they are UK:nsl_single

Note 2 - New large coaches and HGV's have speed limiters based on european legislation, with speed limits around 60mph ???? Seems they're set to whole number in mph rather than a direct conversion from kmh.

Note 3 - Motorways are special roads with speed limits provided by 'motorway legislation'. There are a few special roads that are not motorways and at least one of these appears to be officially lacking legislation needed enforce a speed limit. Speed Limits are given by signs but are not enforceable due to missing legislation????????????????