This little park is a winner for tiny trainspotters! It's located right on a (very well fenced) train line where you can watch metro, diesel and regional trains go through. There are also top views of the city skyline.
Two swings, slides, a rocker, climbing equipment. There is also a BBQ close by. Free parking. Some shade.
Bellair Reserve is on Bellair Street, Kensington in Melbourne's West. You could also just catch the train to Kensington Station.
Don't forget to bring Thomas!