Economics of Railway Working
Express goods trains can be operated economically with comparatively moderate loads if the speed is above the average, as this increases the 'wagon-miles per train-engine-hour'. There is an economic limit to the speed of a railway train because after a certain speed is reached, the cost of raising the speed by a few extra miles per hour increases out of proportion to the gain effected. Passenger services must be provided at reasonable intervals, but the actual frequency will depend on the length of the journey. The possibility of providing intensive services in urban and suburban districts where such are required depends on the line capacity and the actual line occupation. Rail cars in certain districts might be found useful in supplementing the ordinary train services or in developing traffic by increasing the frequency of service. They are also well suited to working into terminal stations since they can be driven from either end.