SUNA collects traffic data from a variety of sources including traffic cameras, road sensors, probe vehicles (including taxis). Relatively static information such as road repairs and special events is also fed into the system.
Congestion information is then transmitted via FM radio and the internet, and used by navigation systems including in-car units to more accurately predict journey times and in some cases to suggest alternative routes.
As a result of the latest expansion, SUNA is available in Melbourne, Sydney, Brisbane, Gold Coast, Adelaide, Perth, Canberra, Hobart, Darwin, Newcastle, Central Coast, Wollongong, Geelong, Ballarat, Bendigo, Sunshine Coast and Ipswich. 97% of the metropolitan population are now covered.