Signalling Query

Generally, we think of the single tracked narrow gauge railways as a less trafficked low cost solution to higher capacity and more expensively built forms of railroading, but there are exceptions to that. These came about because of expanded traffic without any funds to increase line capacity by investment in right of way( as in the TransAndean), or under pressure from things like disasters such as war, or tectonic or climatological events which destroy alternative means of transport. Another form of event is related to one time (or few times) construction projects that are not rail related, but require an existent narrow gauge railroad to provide transport for materials and manpower. Dams, large scale irrigation projects, the creation of alternative transport system artifacts (notably for canals, and other devices to improve interior navigation or build coastal harbors, as well as for building bridges and other components of trunk highway systems), all place burdens on existent narrow gauge railways, that will not justify investments in fixed plant. Another separate category of narrow gauge line, is the passenger oriented operation, that may will increase capacity by investmant in fixed improvements, such as multiple tracking, automatic signalling, grade crossing protection (both rail and road), and so forth. The reasons for not increasing the transport prism while making the move to modern, safer train operating and control devices, can be as simple as that: the fixed plant is imbedded in public streets, and the cost of rebuilding it to a larger gauge exceeds the potential returns. Another factor is that on every continent and in many countries municipal or other local governments did not want the transit rights of way to be accessible to the interstate (i.e. trunk line) freight operators. Local citizens early on, figured out that if the trunk lines could not physically run their trains on their street railways for example, - then some later set of politicians, or those based in a national government could not make an end run around the will of the people as it was set forth in the initial charters granted to transit line operators. So there were, and are, narrow gauge railway systems with a diversity of train control systems comparable to virtually any form found on standard gauge railways.

That said, if you wish to model pre1950 narrow gauge, single track, common carrier railroads in the United States, it will consist of single manual blocks between telegraph stations. The main exception would be a few tunnels controlled by staff systems, but that is probably outside your modelling interest..

Commonly, the agent/operator set the signals against movement. Approaching trains would whistle for clearance. The operator, who may or may not have had the benefit of a track alarm that indicated the direction from which the train was approaching; could also figure it out from the messages passing on the wire. If not he would have to leave the stop indication up while he went outside to see what was up. He had two types of messages for the crews of trains. Basically, they either required the crew to stop the train and sign for receipt of the message, or those that could be passed up by means of hoops to the crew while the train was in motion. The thin manifold paper orders were tied in a string stetched across a hoop (later elastiisized string material). The engine crew picked up a copy and the conductor, or a trainman acting for him, picked up a copy by holding on to the safety railing with one hand and thrusting his free arm through the center of the hoop. He would discard the hoop along the track so the agent/operator could collect same for reuse after taking out the paper message..

The two men in the cab would read and agree to the orders meaning, as would the conductor and trainma(e)n. On freights, the conductor was in the caboose so the pickup was from the platforms, or from the window (in the case of cabooses without end platforms). All read the orders, and hence were in agreement as to contents meaning. This was designed to eliminate the possibility of accidents caused by misinterpretation of the trainorder(s). It didn't always work, since nothing is perfect.

Railroad management, in order to save money, were known to do things that sometimes adversely effected train safety. Additionally, there were times when climatological conditions made any attempt to pass orders to moving trains impossible. So every order was one that had to be picked up by stopping. Under extremely poor conditions finding stations and signals, prior to cab signalization, could become impossible virtually any where in the world.

Stations agents also had some other controlling devices that used train registers and warrants.They mostly applied to one time and out of the ordinary activity, engendered by such things as roadway work, changes in standard operations at junctions and extra train movements that were exceptional in some way.

However, by and large the carbon copies written on manifold paper (referred to as "flimsies" by railroaders) were the principal means of conducting train movement. The station agent would have a semaphore blade type signal that rose or fell. These would have had the usual colored fresnels which passed in front of a fixed lamp. There were also station signals (referred to as "order boards" in railroadese) with horizontally rotating paddles that had a center mounted lantern. It had different colored lenses and rotated with the paddles to display the needed information.

O.S. Nock, your countryman, wrote a book called SINGLE TRACK RAILWAYS years ago, which discussed all the forms of train control used in that format. It should be widely available in used book stores in the UK. Pertinent to understanding what was used by North American railiroads , and I believe you would find very helpful is volume 4 of Anthony Bianculli's TRAINS and TECHNOLOGY: the American Railroad in the Nineteenth Century. This is in print and distributed in UK by Associated University Presses; London. It is pricy, so I would suggest getting it (to read the relative material) at a University or other reference library. If your local municipal library is a member of the Interlibrary Loan Service they should be able to get you a copy to peruse. The kind of signalling used on the standard narrow gauge lines that survived into 20th century, is well covered by Bianculli. The rest of the books in his magnum opus (from Delaware University Press if you are a North Amerucan) are also highly rewarding, but except for some signal towers and interlockers in volume 3, are not germane to train control. Good-Luck, Peter