Demands for Modern Signaling·

b23 Demands for Modern Signaling· By Burt T. Anderson Director, Bureau of Railway Signaling Economics The Hiawatha on the Milwaukee THE NEW era in railroad transporta tion, brought about by streamlining, Faster train speeds necessitate longer air-conditioning, 100 m.p.h. speeds, shortened schedules, 5,000 h.p. loco stopping distances-need for multiple motives, 152-lb. rail, and increased comfort and speed to the public, has aspects, centralized control and cab signals created new problems for the motive power, engineering, maintenance of way, signal, and operating depart ments of the railroads. Fortunately, vices have been installed to expedite mand for expedited traffic and in the signaling art has kept pace with traffic, reduce delays and produce the creased comfort in travel and we now railroad progress. In fact, many of desired operating results and savings have higher train speeds, both freight the new signal developments brought without sacrificing-indeed, while in and passenger, on a greater number about by the intensive research car creasing-safety. The introduction of of regular scheduled runs than ever ried on by the signal and engineering remote control, centralized traffic con before in the history of American rail committees of the Association of trol, directing trains by signal indica roading and without parallel in the American Railroads in conjunction tion, car retarders, modern interlock world. with signal companies antedate the ings, automatic interlockings, spring The recent 12-1/5-hr. run on the new era in railroading. While safety switches, etc., has produced econ Burlington's new "Denver Zephyr" was undoubtedly the original purpose omies, increased safety, and decrea-sed between Chicago and Denver at a rec for which signaling was installed, for operating costs. ord speed of over 83 m.p.h. for 1,017 many years the safety feature has The changing railway and reduced miles and at a top speed of 116 m.p.h. ; been taken for granted and signaling traffic conditions since 1929 have re 88.9 m.p.h. for 41.5 miles on the Mil has been more often installed to fa sulted in curtailed operating expenses waukee's "Hiawatha"; 83.7 m.p.h. cilitate train operation, improve oper and many railroads have adopted for 202.4 miles on the Santa Fe's ating efficiency and decrease the cost those signaling devices which proved "Super-Chief" ; ami 66.2 m.p.h. for of transportation. of economic benefit. The response of 1,048 miles on the Union Pacific's Thus, in recent years, signaling de- the traveling and shipping public in Streamliner, "City of Denver"; these the past two years to the faster sched last three cases being regular sched *Paper prtsented before Central Railway Club meeting in Buffalo, N. Y., on November 12. ules indicates that there is a great de- uled runs, indicate a few of the high 624 RAILWAY SIGNA LI N G · December, 1936 speed trains. Freight train speeds weight train, actually it is the high the signal system to be adopted should have increased nearly SO per cent in speed·freight train which is the deter provide for the most economical oper recent years and high-speed freight mining factor, as not only the speed ation possible, considering all the fac train runs are averaging 42 m.p.h. for but also the length and the weight of tors involved in each particular study. distances over 500 miles so as to pro these trains have been increased. In The railroads operating high-speed vide faster over-night freight service. general, the question of stopping dis trains have solved this problem in Practically all of the high-speed mile tance is one which must be deter each of the ways just mentioned. The age is on territory equipped with au mined by each railroad, depending on tomatic block signals, two-thirds of the varying speed and weight of the the railways with high-speed trains are trains, the grades and ct}rves in equipped with automatic train control· volved, slow orders, and ·local condi or cab signals, and praCtically all of tions. the railways have either centralized It is at this point that the railroad traffic control or train operation by must determine whether to locate or signal indication without the supe relocate the signals for longer block riority of trains. lengths so as to pwvide safety with The day of the 1,250 h.p. locomo the higher speeds or select a system tive, 20 m.p.h. average running speed of signaling, two-block, three-block, for freight trains, and 40 m.p.h for four-block, etc., which will result in passenger trains, the practice in 1910, a reasonable spacing of trains and the highest possible average speed with the existing trackage. Generally the increased stopping distance has been provided by locating or relocat ing the signals but this practice re- . suits in extending the spacing be tween following trains with conse quent decrease in track capacity. While some railroads do not consid er this an important factor, it will be of increasing importance as traf fic increases with improved business conditions, and in many cases even today it is a factor of consequence at "bottle-neck" locations. System of Signal Indications Four-aspect signaling on the Erie to The simplest form of modem way replace old semaphores is typical of side signaling is that provided by a changes made on several roads system of two-block three-indication signals, named "clear," "approach" Chicago, Burlington & Quincy made and "stop." If passenger trains are extensive changes in block lengths run in a number of sections, or are between Chicago and St. Paul, and scheduled close together. or if freight Chicago and Denver, particularly on trains are run in fleets, with the long the signaling installed 15 to 25 years er block spacing, this may result in an ago. The Chicago, Milwaukee, St. Multiple-aspect automatic signal on the Boston & Maine excessive interval between trains. It Paul & Pacific made similar changes, may also result in delays to following and in addition in their heavy traf is out of the question in this era of trains and in uneven operation due fic territory near Chicago, propose to modem railroading when 60 m.p.h. to the brake applications necessary to shorten the blocks and provide three freight and 100 m.p.h. passenger comply with the indication of succes block four-indication signaling. The trains are the daily practice. A few sive "approach" signals. Brake appli Chicago & North Western replaced writers in the press are talking of cations on long freight trains fre some disc signals with three-indica 125-mile speeds provided the motive quently require a stop. On the other tion color-light signals and in their power and track engineers can ar hand, if the traffic density is not too heavy suburban traffic territory pro range for this service. It is probable great, this system of two-block three vided three-block four-indication sig that this tendency to raise the speed indication signals may be entirely naling. The Pennsylvania provided limits as equipment and track facili satisfactory. 8,500-ft. blocks with two-block three ties are provided, will continue, and The next step is a system of three indication signals and added three the signal departments will be re block four-indication signals, named block four-indication signals for 90 quired to design their systems to suit "clear," "approach-medium," "ap m.p.h. speeds. T he Union Pacific in the higher speed operations demanded proach" and "stop." This system pro creased the block lengths on a two by competitive conditions. vides a shorter interval between block three-indication system. The trains, less delay, smoother operation, Missouri Pacific installed over 100 Freight Trains a Real Problem fewer stops, particularly for freight miles of new color-light signaling trains, and a higher average train where manual block was formerly in Probably the first factor involved speed. Similarly, a system of four operation. The Erie installed some in high-speed train operation is in block five-indication signals provides new two-block three-indication color creased stopping distance. While this an increase in average speed and light signals on an up-grade track and problem has been given more atten flexibility of operation over a three three-block four-indication signals on tion with the advent of the light- block system. It will thus be seen that the down-grade replacing old sema-. December, 1936 RAILWAY SIGNALING 625 phore type signals, while the Santa very materially reduces the capacity trol, and modern interlocking facili Fe is adding a fourth indication at of the line. The real solution is to ties, saving every second possible. special locations between Chicago and increase the number of restrictive An equally important factor in sav Los Angeles. The Boston & Maine indications by going to three or four ing delay time to the high-speed and the New York Central have in block signaling as required by the trains is the elimination of delays to stalled four-block five-indication sig local operating conditions. Modern the slower-speed trains on the high nals in heavy traffic territory in order signaling, as designed for safe high speed routes. This factor is not so to expe~ite traffic and reduce delays. speed train operation, should not be important with one high-speed train permitted to restrict efficient train in operation with slower trains, as the Increased Track Capacity operation: schedules of the slower traffic can normally be adjusted to suit the new The advantages to these railw;tys Reducing Delays operation.

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