The Scenario has some glaring issues, mostly with the timetabling. The Haymarket-Linlithgow Leg is unachieveable if you drive it in an manner that approaches realism, even if you drive it like an arcade racecar, aka power notch 8 fromt the standstill it is impossible to arrive on time in Linlithgow, the best I've done was 22 seconds late. Aside from that the Passenger comfort penalties are another hindrance, as they limit you in braking as well as failing to take the route, it's age and it's limitations into account. For example there is no Superelevation and you cannot go Linespeed in the S-Curve 4 miles out from Croy. I think this scenario might need some reworking.
My advice? Copy the scenario and reduce the step percentages to be 75% or less. People do have a tendency to max them up not realising that the time are set for AI driving standards which are less complex than player standards