In a unanimous decision, handed down last month, the UK's highest court ruled that the meaning of 'highway' was not limited to the "surface and top two spits of subsoil" definition set out in historic case law. Rather, the meaning incorporated the full "zone of ordinary use" of the road; a more flexible concept covering various depths of subsoil and airspace height depending on the nature and intensity of the use of the road.
Planning law expert Sarah Chapman of Pinsent Masons, the law firm behind Out-Law.com, said that the case was an important one for those involved with property developments, the majority of which incorporate some form of highway.
"Clarity from the Supreme Court that there is no one meaning of the term 'highway' is helpful; however the flexibility this gives to the term means those involved in highway matters will need to give careful consideration as to how the term is being used and be alive to matters of interpretation – not least ensuring all parties involved in a highway matter are using the same definition," she said.
"The zone of ordinary use for a highway will vary on a case by case basis and could give rise to disputes between landowners and the local highway authority as to the extent of land, vertically and horizontally, that is required for a highway. Airspace and subsoil above and below the surface of the highway may well be included within the 'zone of ordinary use' where they would previously have been excluded from the commonly understood definition of 'surface and top two spits of subsoil'."
"Additionally, there is scope to widen the horizontal extent of the highway beyond its surface, to adjoining land, where such land is required to facilitate the ordinary use of the highway. This will be an important consideration for both the dedication of land as a highway and also the 'stopping up', or closure, of a highway, as parties will need to ensure that only necessary land is included within the highway and any development value in the airspace; subsoil and adjoining land around the highway is protected," she said.
Transport for London (TfL) had sought clarity from the Supreme Court about the legal definition of 'highway' following the transfer to it of roads previously maintained by London's borough councils, in this case the London Borough of Southwark and City of London. The transfer was governed by the 2000 GLA Roads and Side Roads (Transfer of Property etc) Order ('the transfer order'), which provided for the transfer of "the highway, in so far as it is vested in the former highway authority".
The councils argued that only that part of the vertical plane necessary for the operation, maintenance and repair of the road transferred, following the definition of 'highway' as settled at common law. It referred to a long line of cases, culminating in the 1896 decision of the House of Lords in Tunbridge Wells Corpn v Baird, from which the "surface and top two spits of subsoil" definition ultimately emerged. The Supreme Court referred to this as the 'Baird principle'; with 'spit' meaning a spade's depth.
"Although colourful, that phrase says nothing about the necessary airspace above the surface," said Lord Briggs, giving the Supreme Court's judgment.
"There is in my view no single meaning of highway at common law. The word is sometime used as a reference to its physical elements. Sometimes it is used as a label for the incorporeal rights of the public in relation to the locus in quo. Sometimes, as here, it is used as the label for a species of real property. When used within a statutory formula, as here, the word necessarily takes it meaning from the context in which it is used," he said.
In the absence of a common law definition, and with reference to the statutory context, the Supreme Court concluded that transfer order "transfers to TfL ownership of all that part of the vertical plane relating to a GLA road vested in the relevant council on the operative date, but only to the extent that ownership was then vested in the council in its capacity as former highway authority".
"There is no reason why the Baird principle should apply so as to restrict the nature or extent of property being transferred between two public highway authorities, one of which is stepping into the shoes of the other," Lord Briggs said in his judgment.
"The only limitation which does need to be imposed is one which restricts the rights transferred to those enjoyed by the former highway authority in its capacity as such. If the former authority enjoys rights in the vertical plane of the highway in some other capacity, such as adjoining owner, or for other public purposes, there is no sensible reason why those rights should be transferred to its successor as highway authority, merely because of the happenstance that they were vested in the former authority on the operative date," he said.