Sydney's transport system has been ranked second in Australia behind Brisbane for sustainability and effectiveness in a report by a design and consultancy firm.

But on a global measure, Australia's largest city was ranked 51st out of 100 cities around the world, while Brisbane came in at 48th, Canberra 53rd, Melbourne 55th and Perth 87th.

Hong Kong took first place in Arcadis' 2017 Sustainable Cities Mobility Index report, followed by Zurich, Paris and Seoul.

The report said part of the reason for Sydney ranking outside the top 50 cities for transport was due to a concentration of "knowledge worker employment" in the central business district, which was a significant distance from the city's geographical centre.