It is critical that the pavement markings and signs (including electronic signs) used at interchanges and their associated at-grade intersections are:
- consistent with the intended operation of the interchange and intersections
- support the effectiveness of other traffic control devices
- provide adequate warning and guidance to all road users.
The signs and markings required at or in the vicinity of freeway interchanges will involve regulatory, warning, guide (direction and advance direction) and information signs, some of which will relate to particular road users or road user activities. On the freeway itself, the key traffic control devices are the guide signs and associated pavement markings that should provide adequate advance information to drivers to enable them to take up a position early enough to ensure a safe and efficient departure from the facility. Similarly signage and other traffic control devices (e.g. ramp metering signals) on the entry ramps should ensure safe and efficient traffic movement onto the freeway.
Urban freeway to freeway interchanges can be problematic with respect to the satisfactory design and location of advance exit signs and exit signs because of the number of entries and exits and the relatively close spacing of some interchanges. The sign face design and the placement of these signs are critical and should be undertaken by a practitioner who is experienced in the discipline. This is particularly important for system interchanges, and service interchanges that are closely spaced. As a general rule urban freeway to freeway interchanges, because of the high traffic volumes and large numbers of heavy vehicles, should be provided with overhead mounted guide signs. Signs mounted at the side of urban freeways are too often obscured by large high vehicles.
Freeway ramp terminals at the minor road should have all the necessary signs and markings required under local jurisdictional standards and guidelines. These signs may relate to general traffic, parking, pedestrians, cyclists, public transport, or heavy vehicles.
For information on pavement markings and signs for interchanges and associated intersections practitioners should refer to:
- Australian Standard AS 1742 – Manual of Uniform Traffic Control Devices
- NZ Transport Agency Manual of Traffic Signs and Markings (MOTSAM): Part 3 (NZTA 2010b)
- NZ Transport Agency Traffic Control Devices Manual (NZ Transport Agency 2015)
- Guide to Road Design Part 4: Intersections and Crossings – General (Austroads 2009a) or the Guide to Road Design Part 4A: Unsignalised and Signalised Intersections (Austroads 2010a)
- Guide to Traffic Management Part 10: Traffic Control and Communication Devices (Austroads 2009d)
- Specific jurisdictional guides.