The Guide to Road Design Part 4A: Unsignalised and Signalised Intersections (AGRD Part 4A) provides road designers and other practitioners with guidance on the detailed geometric design of all at‑grade intersections (excluding roundabouts). However, some of the guidance in AGRD Part 4A may be appropriate for the design of approaches to roundabouts and is relevant to the design of ramp terminals where freeway ramps intersect with the minor road at an interchange.
AGRD Part 4A does not provide all the information that is necessary to design a satisfactory intersection and therefore, depending on the situation, should be used in conjunction with all other parts of the Guide to Road Design, in particular:
- Part 4: Intersections and Crossings: General (Austroads 2017)
- Part 4B: Roundabouts (Austroads 2015c)
- Part 4C: Interchanges (Austroads 2015d).
In addition, road designers should also refer to the Austroads Guide to Traffic Management Part 6: Intersections, Interchanges and Crossings (Austroads 2013a) which provides guidance on the traffic management aspects of intersection design and road users’ requirements.