SYD - WALK TO WOLLI CREEK STATION
For some healthy exercise and to avoid the private railway fare, it is possible to walk from SYD International terminal to Wolli Creek railway station in about 20-25 minutes. I have done it three times, twice with no luggage and once with a backpack. Each time I saw airport employees doing the same walk. You start by crossing the river on the bridge behind the car park.
The only hard part is crossing busy Marsh St, which is best done near the Hilton Hotel, where the median strip is wider.
From Wolli Creek station, you pay the normal State Rail fares only, i.e. not the Airport line surcharge.
I do NOT recommend doing this walk with luggage other than a backpack.
(From the domestic terminal you would walk to Mascot Station, not to Wolli Creek).