I know nothing about this project and probably shouldn't comment but from previous logistics projects I've worked on I've learned that maintenance costs from wear and tear all seem to increase non-linearly with mechanical speed. An everyday example is that some buildings choose to run their elevators at slower speeds for this reason, but the speeds of industrial and logistical conveyor belts are carefully chosen with this in mind too. Of course air resistance also goes up non-linearly with speed, and that might be a factor here.