- inflow of ratio of ppl choosing cars is mainly affected by effect of mrt utilisation. effect of degradation is minimal because after the initialisation period, we always have an excess of money to repair mrt and so there is zero degradation.
- even after factoring in money, the scale of degradation is way smaller than the effect of mrt utilisation: degradation is in units of utilisation and degradation describes utilization not covered by money for maintenance, which is very little.