| Centreline | The line, normally down the centre of a road carriageway, from which all the road geometry is derived. |
| Chainage | The horizontal distance along a route. For example, the centreline chainage is the distance along the centreline following the curves of the road. The chainage is the 2D plan distance which does not take into account variations in the vertical. The chainage only represents the true distance when the route is completely horizontal. Where the route is not horizontal the true distance is longer than the chainage distance. |
| Channel | The channel is edge of the road carriageway at the base of the kerb. The channel is normally where rainwater would collect and run along to a gulley. Where the road carriageway slopes down away from the kerb (for example, with super-elevation round a curve) the edge line is still referred to as the channel. |
| Driveway | The vehicular access to a property. Sometimes known as a vehicle crossing. Comprised of a kerb ramp and a footway crossing |
| Gulley | A gulley is the drainage point on a channel where rainwater drains off the carriageway. |
| Fillet | A fillet is a curve which tangentially fits into an angle to round it off. For example, a road centreline normally comprises straight lengths joined by fillet curves so that it is a smooth path. |
| Footpath | A pedestrian walkway. It is common for the term to denote a footway, though a footpath can generally be any walkway not adjacent to a road. |
| Footway | The pedestrian path at the side of a road. |
| ICD | Inscribed Circle Diameter. This refers to diameter of the outermost circle of the roundabout. The term ICD is often used to refer to the circle itself rather than the diameter. |
| Interface | An interface is where the edge of the new designed surface joins with the existing ground. Commonly the designed level is interfaced to the ground level by means of a slope of given grade. |
| Invert | The lowest point on the interior circumference of a pipe, or the bottom of a manhole |
| Kerb | The step up at the edge of the road carriageway, often onto the footway. The kerb face usually makes a channel to collect water at the edge of the road. |
| Pram Crossing | A cut down kerb which improves accessibility for baby carriages, wheeled or mobility impaired pedestrians. |
| Soffit | The highest point on the interior circumference of a pipe. Opposite of invert |
| Station | The horizontal distance along a route. For example, the centreline station is the distance along the centreline following the curves of the road. The station is the 2D plan distance which does not take into account variations in the vertical. The station only represents the true distance when the route is completely horizontal. Where the route is not horizontal the true distance is longer than the station distance. |
| Transition | A curve smoothly varying from one radius to another. Geometrically, the transition curve is part of a spiral. A transition would normally be used on a highway either side of a fixed radius bend, to smoothly change the driving path from the straight (infinite radius) to the fixed radius. If a transition was not present the driver would be required to turn the steering wheel instantaneously at the start and end of the curve. |