Via Flemington using both existing rail line and a new rail tunnel. This option would include some tunnelling but incorporate the existing Flemington rail reservation. It would also include a new station at Highpoint shopping centre and run through contaminated land at the Maribyrnong Defence Site. Found the least satisfactory of the four routes when modelled by Public Transport Victoria in 2013 because it was expensive but still had serious social and construction impacts.

Via the Maribyrnong Defence Site using tunnelling all the way. More expensive than any other project - as much as double, according to the 2013 study - but also the quickest route to the airport. Along with extensive tunnelling, this route would need to deal with serious contamination at the federal government’s Maribyrnong Defence Site. Canberra is in the process of selling that site for housing and is keen to make the airport rail link part of that "legacy" project.