Within this site and other road sites, you'll find some abbreviations and also jargon. The table below tries to explain what some of the more common terms are. Where possible, official terms are used. Information on this page is compiled with data from government websites, Cameron Kaiser and Sam Laybutt (Ozroads). Click or tap here for route numbering information.

Term:
Definition:
AD / Advance Directional Sign:
Sign giving an early warning of destinations ahead.
Alternative Route / ALT:
Alternative alignment of a route to serve other areas, or to function as a bypass.
Alignment:
The physical setup of a route, which is to say, the actual road itself.
At-Grade Intersection:
Intersection where there is no separation of traffic streams, for example, no bridges or underpasses. At-grade intersections are usually controlled with some sort of device, either stop signs, give way signs or traffic lights.
Bypass:
A route branching off from a route to go around "pass by" a region, and rejoin it later.
Carriageway:
Another name for roadway, especially if a road is split in two directions by a median strip.
Department for Infrastructure and Transport:
The former name of the government body that maintains main roads in the state of South Australia. Former names include Transport SA and South Australian Highways Department.
Divided Road / Dual Carriageway:
Term indicating that groups of lanes travelling in different directions are physically separated into two streams, not just with painted lines. Medians, Traffic Islands and Jersey barriers are some methods of separation.
Duplex / Multiplex:
Refers to multiple routes being signed over the same alignment.
Exit Numbers:
Can be either the distance from the start of a freeway or simply in sequence and is a method of tagging exits with a unique numerical identifier, as an aid to the motorist.
Expressway:
A main road designed to high standards that may or may not have signals or dual carriageways, but does not have properties connecting to it.
Gantry:
A structure, usually made of steel used to display signs and similar traffic control devices over a roadway.
Grade-Separated Interchange:
Interchanges with ramps or connectors to isolate different traffic streams so that conflicts are minimised.
ID / Intersection Directional Sign:
Sign used at an intersection or similar detailing direction options.
Jersey Barrier:
Standard concrete divider with a thick tapered base and thinner top. This is one method of achieving a dual-carriageway configuration.
Kilometre Plate:
Kilometre signs appear on Australian highways and roads informing the motorist how far it is to the next major town or city. They normally appear every 5km, however this varies depending on the state or region.
Limited Access Road:
A road that does not have automatic right-of-way granted to owners of abutting properties. Lanes travelling in different directions may be physically separated, and the route may have interchanges with ramps or other devices to isolate traffic streams.
Main Roads Queensland:
The name of the government body that maintains main roads in the state of Queensland, Australia. The department has had several incarnations, the including the Department of Main Roads and Queensland Main Roads.
Main Roads Western Australia:
The name of the government body that maintains main roads in the state of Western Australia.
Median Strip / Traffic Island:
A piece of earth or man-made fixture designed to separate flows of traffic away from each other.
Motorway / Freeway / Tollway:
A free or motorway is a road that is usually divided and does not allow traffic to stop at signs or signals or allows traffic to enter without using an on or off ramp. Tollways in Australian terms are roads on which a motorist pays a special fee to use it.
Metropolitan Route / MR:
The name given to the blue shielded state routes marked within metropolitan Melbourne. The name originates from the fact that for over 10 years these routes only existed within metropolitan Melbourne.
National Highway / NH:
The National Highway scheme is a now defunct federal classification of road which was 100% funded by the Commonwealth Government. These roads were usually delineated by a green and gold National Route shield.

A National Highway route marker is a National Route marked by the same shield as the National Route shield, but with a green and gold colour scheme and usually the word "National" placed at the top of, but inside, the shield. These routes were specially marked to show that they were funded 100% by the Commonwealth Government between 1974 and 2004. Some sections of routes marked by the National Highway shield were not part of the National Highway network but were marked thus for continuity in navigation.
National Route / NR:
A route marked by a black and white shield for navigation purposes. These routes are generally of national importance, although there are exceptions.
On Ramp / Off Ramp:
A special short road used to enter or exit a main road such as a freeway.
RD / Reassurance Directional Sign:
Sign used to detail towns ahead and their distance.
Road Geek:
A name given to a person that has a significant interest in roads and related infrastructure.
Roundel:
A red circle with a diagonal line through the inside used to prohibit an action.
Route Marker / Shield:
A shape, usually including a number but sometimes including a picture instead, used to denote a route for navigation purposes. The shape of the shield is related to its importance as a route.
Safety Ramp / Arrester Bed:
Used along some steep roads, these devices are a bed along the ground veering off from a route, usually up-hill to stop runaway vehicles.
State Route / SR:
A route marked by a blue, spade-like shield for the purposes of navigation. These routes are generally of inter-regional or intra-metropolitan significance and of less importance than National Routes.
Super-2:
A limited access road that may be destined to become duplicated into a divided road.
Transport Canberra And City Services:
The Australian Capital Territory government department that manages roads, public transport and city services. Formerly known as TAMS: Territory and Municipal Services.
Transport for New South Wales:
The name of the government body that maintains main roads in the state of New South Wales, Australia. Former department names include Roads And Maritime Services, Roads and Traffic Authority, Department of Main Roads and Main Roads Board.
Trailblazer:
A stand-alone route marker / shield, not included as part of a directional sign.
VicRoads:
The name of the government body that maintains main roads in the state of Victoria, Australia.