21 kilometres of overhead needed you say? Maybe after the rest of Melbourne's current suburban rail system enters the 20th century (yes, 20th) by fixing the last of the single-track bottlenecks and electrifying Melton/Tarneit/Wyndham Vale. If lucky, Wallan might just beat Bacchus Marsh to having a Comeng sit in the platform (if they still exist by then).
For comparison, 21 kilometres is roughly between Flinders Street and any of these stations: Cheltenham, Westall, Glen Waverley, Mitcham, Greensborough, Epping, Roxburgh Park, Keilor Plains, Caroline Springs and Laverton, of which only Caroline Springs is lacking overhead. 21 kms is also longer than the Sandringham, Alamein, Upfield and Williamstown lines in their entirety.