[quote=apw5910]Get back to us when it gets better than this:
Feb 1983 (Vol 34 No. 544)
Railway operations in the 'great wet' May 1889 (Audley, D.)
This detailed and interesting article describes the difficulties faced by the NSWR during the unseasonal wet conditions experienced in May 1889. 11 photos. Contribution from D Burke appears in Bn 574, Aug 1985, p 192.
The BOM site has lots of old data.
530 mm in May 1889 in Sydney, 480 mm of which fell in just 4 days.
Not to overlook the Maitland Floods of 1956 or thereabouts - I think Flood Gates still protect Maitland Station.
I haven't really seen much rain damage to railways in my time in Sydney, I do recall the lower level of the Flying Junctions being under water for an hour or so following a Thunderstorm in the early 1990's, and I remember the ESR being flooded for a few hours during the 1980's between Town Hall and Central (the line is below sea level there) when pumps failed during a storm.