The extemities of Canberra span 50 kilometres, north-south. With the exception of three routes, Melbourne's tram network, the largest of any city in the world, lies within a radial span of 10 kilometres centred on the CBD, and within two arcs that total about 180 degress (see overlay map below).
The diagram at the right shows a map of Sydney overlaid by a map of Canberra to the same scale. Clearly if one is planning a rail network for the Canberra of the future it would be ridiculous to build a light rail network given the travel distances that are involved even now in Canberra.
Heavy rail offers high capacity and high speed. A spine route would link Tuggeranong, Woden-Weston, Molongolo, Civic-East Belconnen and Gunghalin, paralleling the Parkways. An east-west line from West Belconnen to the Airport and in the direction of Bungendore is a second consideration.
A major advantage of planning for a heavy rail network is that it would link seamlessly to a future high-speed national network, connecting though Yass or Goulburn.
Melbourne tram network overlaid on Canberra map to same scale