Guidance

Section 6: glossary of technical terms

Published 17 December 2024

Applies to England

All-purpose trunk roads	Centrally owned and maintained ‘A’ roads.
BCD	Base Condition Data. A bespoke data file format for input of data to HAPMS.
BVPI	Best Value Performance Indicator – BVPIs show the relative performance of English local authorities for different aspects of performance. Replaced by National Indicators. In turn replaced by the Single Data List in 2011.
Carriageway	The paved area of the highway carrying vehicular traffic and including any hard shoulders and marginal strips.
CHART	The Computerised Highway Assessment of Ratings and Treatments. Developed in the 1970s to provide a system of assessing the structural maintenance needs of highways, replaced by UK Pavement Management System and SCANNER.
Classified roads	Local authority owned and maintained roads with ‘A’, ‘B’ or ‘C’ classification.
CSC	Characteristic SCRIM Coefficient. An estimate of the underlying skid resistance once the seasonal variation has been taken into account.
CVI	Coarse Visual Inspection – a method of inspecting road condition at network level developed as part of the UK Pavement Management System.
DBFO	Design, build, finance and operate.
Defects index	Representation of the carriageway defects that will show the trends in condition (1977 value = 100).
DVI	Detailed Visual Inspection – a method of inspecting road condition developed as part of the UK Pavement Management System (see below).
Flexible pavement	A pavement with the base (Road base) and all layers above the base of bituminous material.
Flexible composite	A pavement with a cement-bound base and bituminous upper pavement layers.
Footway	Any area alongside a road intended for use by pedestrians. (Colloquially a footway will be described either as a ‘pavement’ or as a footpath alongside a road).
GAIST	A road condition monitoring supplier applying video-based methods to inspect road condition.
HAPMS	A generic term to cover the computer systems and related engineering and business processes that comprise the Highways Agency Pavement Management System used by National Highways.
HMDIF	Highways Maintenance Data Interchange Format. A standard file format for the exchange of Highways-related data in UK Pavement Management System.
In-situ recycling	Reusing of the existing construction in-situ, with the addition of Foamed Bitumen, Bitumen Emulsion and Cement in accordance with BS9228. Includes Shallow (Retread), Medium (for example, Regen), and Deep in-situ recycling, with a Surface Dressing or Asphalt surface course finish.
Investigatory level	The level of condition at which consideration is given of the need for maintenance. At this juncture, all available evidence (for example, accident rates) would be taken into account.
Local roads	Local authority maintained ‘A’, ‘B’, ‘C’ and unclassified roads. These are also known as Non-Trunk roads.
Long life pavements	A flexible pavement that is thicker than traditional pavement and has a low deflection. Residual life (see below) is not used for long life pavements.
Macrotexture	The texture of road pavements results from the size and distribution of the aggregates within it. Texture ranges across a broad wavelength spectrum from the micrometre to the decimetre range.  The term macrotexture is used to describe texture with wavelengths between to 0.5 and 50mm.
Mean Summer SCRIM coefficient	Mean of 3 or more SCRIM Coefficients measured for a length of road at well spaced intervals between May and September in a year.
Megatexture	The texture of road pavements results from the size and distribution of the aggregates within it. Texture ranges across a broad wavelength spectrum from the micrometre to the decimetre range. The term megatexture is used to describe texture with wavelengths between to 50 and 500mm.
Micro surfacing	A site-mixed, cold-applied asphalt surface course in accordance with Clause 918.
Microtexture	The texture of road pavements results from the size and distribution of the aggregates within it. Texture ranges across a broad wavelength spectrum from the micrometre to the decimetre range. The term microtexture is used to describe texture with wavelengths up to 0.5mm.
Motorway	A particular type of road with restricted use carrying predominantly long-distance traffic. Most motorways are the responsibility of NH (formerly HE) but there are some short lengths of local authority motorways.
NI	National Indicator. Show the relative performance of English local authorities for different aspects of performance. Replaced in 2011 by the Single Data List.
Non-trunk roads	Local authority maintained ‘A’, ‘B’, ‘C’ and unclassified roads. These are also known as local roads.
Non-principal roads	Local authority maintained ‘B’ and ‘C’ roads.
Overlay	Material placed on top of the existing pavement in a layer (or layers) of regular thickness. This is a more substantial treatment than surface dressing.
Pavement	Technical term for the carriageway of a road. Note this is not a footway (see definition above).
Preservation and rejuvenation	Spray-applied, penetrative preservative in accordance with Clause 950, or a Rejuvenator that penetrates and changes the rheology of the binder.
Principal roads	Local authority maintained ‘A’ roads and motorways. In general, they carry less traffic than all purpose trunk roads which are ‘A’ roads and motorways owned and maintained by central government.
Programmed patching	Patching and minor repairs, including haunching, to flexible and concrete carriageway. Patching and haunching associated with reconstruction, overlay, resurfacing, and surface dressing are excluded.
Reconstruction excluding in-situ recycling	The removal of some or all of the structural layers of a road pavement and their replacement with new material, including a new surfacing. This is a more substantial treatment than overlay.
Residual life	The expected period before the structure of a flexible or flexible composite pavement reaches an ‘investigatory condition’. At this point further deterioration is no longer predictable, so that even though the road may still be serviceable it is not possible to predict how long it will remain so. Residual life is therefore a similar concept to the supermarket ‘shelf life’.
Resurfacing	The removal and replacement of the existing surface, in order to restore the running surface and improve surface characteristics.
Rigid composite pavement	A pavement in which the structural layer is cement based concrete and the surface layers are bituminous material.
Rigid pavement	A pavement in which the structural layers and the surface are cement-based concrete.
SCANNER	Surface Condition Assessment of the National Network of Roads. Vehicle-mounted automated pavement surface condition surveys for local authority roads based on the TRACS surveys used on the trunk road network. Like TRACS, the specification covers the requirements for both the machinery used and the survey process.
SCRIM	Sideway-force Coefficient Routine Investigation Machine – a lorry-based machine that when driven over a pavement surface, measures the resistance to skidding of the wet pavement surface.
Single annual SCRIM survey	All of lane 1 of the network is surveyed once during the SCRIM testing season in each year. In successive years each road length is tested in the early, middle and late parts of the season.
Surface dressing	A single/double/triple layer of aggregate combined with one or more layers of binder (for example. bitumen) to form a running surface. This may be laid over the existing surface.
Thin surfacing	Thin surfacing systems are machine-laid proprietary mixes of asphalt that have the capability to regulate and smooth the surface profile of a road pavement, restoring surface texture and skid resistance.
TRACS	Traffic Speed Condition Survey – a label to describe a methodology for machine-based surveys of surface condition, including cracking and rutting, of the trunk road network in England. The TRACS specification covers the requirements for both the machinery used and the survey process.
Trunk roads	Motorways and all purpose trunk ‘A’ roads owned by central government and for which, in England, NH (formerly HE) have responsibility for maintenance and operation. These are strategic roads with a high proportion of long distance traffic, although some trunk roads may also have lengths, with the same number, designated as an ‘A’ principal road, where traffic is predominantly local in nature.
TTS	TRACS type surveys. Now known as SCANNER surveys.
UKPMS	United Kingdom Pavement Management System – this is a standard logical design for software used by local highway authorities for the management of the maintenance of their road networks. The development of UKPMS was funded by DfT. A number of companies market software that meets the UKPMS requirements. Associated with UKPMS are road condition monitoring surveys (including SCANNER, CVI and DVI, see above) and standard ‘rules and parameters’ to be used when processing survey data for ‘national’ purposes for example, for reporting against single data list items 130-01 and 130-02.
Unclassified roads	Minor roads which are not designated as classified roads, and which are owned and maintained by a local highway authority.
Vaisala	A road condition monitoring supplier applying a combination of Artificial Intelligence and video data to inspect road condition.
XAIS-PTS	A road condition monitoring supplier applying a combination of video data, LiDAR and SCANNER technology, as well as engineers surveys, to inspect road condition.

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