A high proportion of road traffic crashes occur at intersections. This is due to the often unavoidable conflict points where vehicle and other traffic paths cross, merge or separate. In 2023, for example, approximately 45% of all reported casualty crashes in Victoria and NSW occurred at intersections. Especially evident in urban areas across Australia, serious intersection crashes frequently involve vulnerable road users such as pedestrians, cyclists, and motorcycle and scooter riders. While relatively less common in rural than urban areas, rural intersection crashes can often be severe due to high speeds and other factors such as impact angles. According to the data cited above, more than 95% of intersection crashes occur at T- and Cross-type intersections (including roundabouts) in comparable proportions. At the broadest level, intersections are generally characterised as either signalised or unsignalised (Information sourced from Austroads Guide to Road Safety Part 2 and (US) FHWA “Intersection Safety”)
Signalised intersections
Signalised intersections are, by definition, “controlled” intersections. This is typically achieved using traffic lights, which are often programmed to prioritise the highest volume traffic paths. From an operational perspective, this is clearly a logical traffic management approach. However, seeking to maximise network efficiency can necessitate a compromise between mobility and safety. A safe system approach attempts to minimise this trade-off through engineering and design features such as protected turns, speed reduction/management measures, and limiting the number of conflict points, among others. Red light running is a major contributing factor to intersection crashes.
Unsignalised intersections
Unsignalised intersections may be controlled or uncontrolled, where the latter will generally only be found on low-speed roads of the lowest traffic volumes, such as in rural, remote and some residential areas. Controls at unsignalised intersections include Stop signs and Give Way (yield) signs on at least one of the intersection approaches. For unsignalised intersections, a safe system approach would always include the use of such controls except where speeds are appropriately and reliably managed through other measures.
[1] Information sourced from Austroads Guide to Road Safety Part 2 and (US) FHWA “Intersection Safety”.
