Highway & Streets Glossary#

Plain-English definitions of highway, pedestrian and street-design terms used across Farnham Voice pages. This glossary is intended to make council and transport terminology easier to understand.

A–Z#

85th percentile speed — The speed at or below which 85% of vehicles are travelling at a given location. Highway engineers commonly use this measure because it represents the speed most drivers consider reasonable for the road. It is often used when assessing whether a speed limit is appropriate or whether traffic calming is needed.
Belisha beacon — The flashing amber globe mounted on a black-and-white pole at a zebra crossing.
Build-out — An extension of the pavement or kerb into the carriageway. Build-outs can narrow the road, shorten the distance pedestrians need to cross, protect parking areas or encourage lower vehicle speeds. (Surrey CC)
Carriageway — The part of a road primarily intended for vehicles. What is commonly referred to as the road itself.
Chicane — A series of staggered features that changes the otherwise straight path of vehicles. It is normally used to reduce vehicle speeds. (Surrey CC)
Collision cluster — A group of recorded collisions occurring within a defined area or stretch of road. Identifying clusters helps highway authorities assess whether a location has a pattern of collisions that may warrant investigation or intervention.
Controlled crossing — A pedestrian crossing where traffic is required to respond to formal controls, such as signals or zebra-crossing markings. Examples include zebra, puffin and toucan crossings.
Desire line — The route people naturally prefer to take between two places. In pedestrian planning, this can help identify where people actually want to cross a road rather than where existing infrastructure directs them.
Dropped kerb — A section where the pavement is lowered to approximately carriageway level. It allows easier movement for wheelchair users, mobility aids, pushchairs and others who may find a standard kerb difficult to negotiate.
Granite setts — Small blocks of natural stone used as paving or road surfacing. They can also create a visual or textural change within a street.
KSI (killed or seriously injured) — A standard measure used in road safety data to count the number of people killed or seriously injured in recorded collisions. It is used by highway authorities, police and the Department for Transport when assessing road safety.
Pedestrian crossing — A location designed or designated to help pedestrians cross a road. Different crossing types provide different levels of priority and control.
Pedestrian refuge / refuge island — A protected area in the centre of a road where pedestrians can wait. It allows the road to be crossed in two stages rather than requiring pedestrians to cross both directions of traffic at once.
Personal injury collision (PIC) — A collision recorded by police in which at least one person was injured. Only collisions involving injury are included in official road safety statistics (STATS19). Damage-only incidents are not recorded in this dataset.
Raised table — A relatively long, flat section of carriageway raised above the normal road level. It may cover a junction or crossing area and can be used to reduce vehicle speeds. (Surrey CC)
Recorded collision — A road traffic collision reported to and recorded by the police. In the UK, only collisions involving personal injury are included in the STATS19 dataset published by the Department for Transport. The term “collision” is the standard used in official road safety data, replacing the older term “accident.”
Rumble strips — Raised or textured features that create noise or vibration when vehicles pass over them. They are generally intended to alert drivers or encourage lower speeds. (Surrey CC)
SAMs (Smiley Activated Messages) — Electronic roadside signs that detect approaching vehicle speeds and display a message or symbol intended to encourage drivers to comply with the speed limit. They are a form of vehicle-activated sign.
Sight stopping distance — The minimum distance a driver needs to see ahead in order to stop safely if an obstacle appears. It depends on vehicle speed, driver reaction time and road surface conditions. Highway authorities use it when assessing whether a road layout provides adequate visibility.
Speed cushion — A raised traffic-calming feature that covers only part of the carriageway width. Its dimensions can allow vehicles with a wider wheel track, such as buses, to pass with less vertical movement than smaller vehicles. (Surrey CC)
Suppressed demand — The idea that difficult or hostile road conditions can discourage people from walking, cycling or crossing at a particular location. A low observed pedestrian count does not necessarily mean a crossing is unnecessary — it may reflect the difficulty of crossing rather than a lack of need.
Tactile paving — Paving with a raised surface pattern designed to provide information or warnings that can be detected underfoot or with a cane. Different patterns have specific meanings and are particularly important for blind and partially sighted pedestrians.
Textured surfacing — Surfacing that differs in texture, material or appearance from the surrounding carriageway. It can be used to emphasise a particular area or influence how drivers perceive the street.
Traffic calming — Physical or visual measures designed to reduce vehicle speeds, discourage inappropriate driving behaviour or change how traffic moves through a street. Examples include raised tables, build-outs, chicanes and road narrowing. (Surrey CC)
Uncontrolled crossing — A place where pedestrians cross without traffic signals or zebra-crossing controls. It may still include features such as dropped kerbs, tactile paving, a refuge island or a raised table.
Vehicle-activated sign (VAS) — An electronic sign triggered by approaching vehicles, often when a vehicle exceeds a specified speed. It may display the speed limit, a warning or another road-safety message.
Vertical deflection — A deliberate change in carriageway height designed to influence vehicle speeds. Examples include road humps, speed cushions and raised tables. (Surrey CC)
Visibility splay — An area that needs to remain sufficiently clear so road users can see approaching vehicles, pedestrians or other hazards. Required visibility depends on factors including road layout and vehicle speeds.
Zebra crossing — A controlled pedestrian crossing identified by black-and-white road markings and flashing Belisha beacons. Drivers and cyclists must give way to pedestrians who are on the crossing.

Definitions marked (Surrey CC) are adapted from Surrey County Council’s Healthy Streets glossary. Other entries are plain-English explanations of commonly used UK highway and street-design terminology.

Where a formal legal or technical definition applies, the relevant legislation, Department for Transport guidance or highway-authority standard takes precedence over this glossary.