. Electric railway journal . of stop varies fromfive to ten seconds. The importance, from a power con-sumption standpoint, of shortening the stop to a mini-mum, with maintenance of a given schedule speed, hasbeen shown in Fig. 3. However, there are conditionswhere, instead of maintaining the schedule speed, therunning time is extended. To explain this latter con-dition the curves shown in Fig. 5 were made. With acar geared to a free running speed of 25 , makingseven stops per mile, it is possible to make a schedulespeed of 10 with ten-second stops. With five-second stops the sched
. Electric railway journal . of stop varies fromfive to ten seconds. The importance, from a power con-sumption standpoint, of shortening the stop to a mini-mum, with maintenance of a given schedule speed, hasbeen shown in Fig. 3. However, there are conditionswhere, instead of maintaining the schedule speed, therunning time is extended. To explain this latter con-dition the curves shown in Fig. 5 were made. With acar geared to a free running speed of 25 , makingseven stops per mile, it is possible to make a schedulespeed of 10 with ten-second stops. With five-second stops the schedule speed will be increased to , or 12 per cent. 200 = 160 c o L 120 D_ t 80 Z>O £ 40i 12 per Mi le Data : Weight of car, 4 0 tons : accelerating force 120 lb. per ton :braking force, 150 lb. per ton ; coasting 20 per cent of power-onperiod ; duration of stop, fifteen seconds. CAR OPERATING EFFICIENCY—FIG. 7—GRAPHS SHOWING RELA-TION OF SCHEDULE SPEED AND ENERGY CONSUMPTIONTO STOPS PER MILE. 692 ELECTRIC RAILWAY JOURNAL [Vol. XLVII, No. 15 The curves of Fig. 6 show data for a 20-ton cargeared for free running speeds of 15, 20, 25 and and the corresponding watt-hours per ton-mileare also shown. Fig. 7 gives the same information fora 40-ton interurban car, geared for 30, 40, 50 and free running speeds. The relation of stops permile, schedule speed and power consumption is clearlyshown. With the 20-ton car, geared for a free runningspeed of 25 , by comparing the services of sevenand nine stops per mile, it will be noted that with sevenstops per mile it is possible to make schedulespeed, and that the power consumption is watt-hours per car-mile, while with nine stops per mile aschedule of can be made with an energy con-sumption of per car-mile. To illustrate the power and schedule savings that canbe made we can assume that a car makes 40,000 car-miles per year and the energy costs 1 c
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