Yours trains doesn't reach max speed between stations or doing it at the end of the route which cost you time. I recommend to upgrade your train fleet to max (locomotive and wagons). Pay more attention to power of the train not the vmax. And last but not least, more advanced vehicle = more money for the route, you can make 2x money on the same line with the same numbers of passengers but newer vehicle, i know they cost more annualy but imo it's worth it