There must be a section in the Highways Act which enables highway authorities to prevent the laying of SU's equipment under the carriageway, although I can't recall it off hand. After all, we don't see BT digging up the M4 (under statutory undertakers are available)
The M4, like all other motorways and one or two other cases, is a
special road as defined by the Special Roads Act of 1949, now part of the Highways Act. Different rules apply.
Yes they are 'Protected Streets' under Section 61 of the New Roads and Street Works Act 1991:
(a)any highway or proposed highway which is a special road in accordance with section 16 of the Highways Act 1980, and
(b)any street designated by the street authority as protected.
However the Secretary of State can prescribe criteria thatstreet authorities must use in deciding whether to designate a protected street (Section 62)
The guidance in the
Code of Practice for the Co-ordination of Street Works and Works for Road Purposes and Related Matters
States that:
Streets may be designated as protected, only if they serve, or will serve, a specific strategic traffic need, with high and constant traffic flows, and there is a reasonable alternative route in which undertakers can place the equipment, which would otherwise lawfully have been placed in the protected street. This includes services to existing or proposed properties in the street, or trunk supply routes passing through the street.
This also identifies that various features can be protected by other legislation including:
Priority lanes
These include cycle routes and bus lanes. The Special Designation Description indicates the type of priority lane.
Transport authority critical apparatus
This is apparatus used, or owned, by a Transport Authority that is critical to the operations of the Transport Authority and if damaged or interrupted could
disrupt or temporarily stop services; for instance damage to high voltage cables supplying power to a rail network would cause its closure and severe inconvenience to their passengers.
However, Section 91 of the New Roads and Street Works Act 1991 defines a transport authority as:
(1)In this Part—
(a)“transport authority” means the authority, body or person having the control or management of a transport undertaking; and
(b)“transport undertaking” means a railway, tramway, dock, harbour, pier, canal or inland navigation undertaking of which the activities, or some of the activities, are carried on under statutory authority.
So I am not clear that a busway is a 'transport undertaking'