The only problem with train from the airport to the Quay is weekend track work where busses replace trains between the airport and Central station. This is organised chaos. The worst part is being dumped at Central station and lining up to buy a ticket to go anywhere else. It takes ages because most in the line want to discuss ticket options with the person behind the window.

. If this happens, it will be on a weekend rather than week day. Forget about the 3.5 hr city run if you see signs directing you to busses instead of the train at SYD T1.