replacing old vehicles doesn’t bother me.. for train I simply first buy a new one and put it on same line and after that recall old train to depot …
for buses and trams .. usually all buses on same line have same age … so first I buy exact number of new buses … recall entire line to depot and set same line to new vehicles …
doesn’t take to much work… but i’m a casual player who enjoy the life in game .. (play on easy)