QUESTION 4 4.1 4.2 An electric train is required to maintain a scheduled average speed of 90 km/h between two stations that are 11 km apart. Allow for 30 seconds for stopping time at one station. The acceleration is 0,7 m/s and the braking retardation is 0,9 m/s. Assuming a simplified rectilinear speed-time curve, calculate the maximum speed of the train. Name FOUR basic types of maintenance philosophies that one will consider when maintaining the rolling stock in the rail transport industry and give a brief description of each type. (12) (8) [20]