Standards for North American railroad signaling in the United States are issued by the Association of American Railroads (AAR), which is a trade association of the railroads of Canada, the US, and Mexico. Their system is loosely based on practices developed in the United Kingdom during the early years of railway development. However, North American practice diverged from that of the United Kingdom due to different operating conditions and economic factors between the two regions. In Canada, the Canadian Rail Operating Rules (CROR) are approved by the Minister of Transport under the authority of the Railway Safety Act. Each railway company or transit authority in Canada issues its own CROR rulebook with special instructions peculiar to each individual property. Among the distinctions are: The US has a much longer history of power operation of switches ("points" in UK parlance) and signals. The US and Canada departed from UK practice wherein a semaphore blade is devoted to each route (Route Signaling). General North American practice is to group routes by speeds and use a single blade for, say, "medium speed" regardless of the number of routes involved (Speed Signaling). The primary exception to this situation is in the field of heavy rapid transit, such as subways and elevated lines, which make use of a localization of the British practice, or a combination of the AAR and British systems. Some freight railroads also still use route signalling.
History of railroad operating rules
In railroad operations, nearly every aspect of employee behavior is governed by operating rules. Employees who perform their jobs in an unsafe manner usually violate operating and safety rules. Human-factors related incidents are caused, or influenced by, unsafe work behavior and attitudes, as opposed to non-behavior related factors like inclement weather or undetected faulty track. Therefore, nearly all human-factor incidents and injuries can be associated with one or more operating or safety rule violations.
By the 1850s, railroad operating rules, often printed as pamphlets or on the back of a time card, had evolved to near universal application. On April 14, 1887 representatives of 48 railroads voted for the adoption of what is now known as the Standard Code of Operating Rules (SCOR), published by the AAR. Thus, all railroad rule books in North America today have as their foundation the SCOR in both development and application.(Shaw, 1978)
The SCOR, however, was never intended to be used as a working rulebook. Rather, its primary intention was to standardize operating practices to the extent practicable while still preserving the flexibility of individual railroads to either modify or omit rules at their discretion. Even rulebooks with identical phraseology could be interpreted and applied differently on different railroads. Although used as a reference book, the SCOR was primarily a matrix document, from which the industry could establish standard text and a common numbering system. Until recently, in fact, railroads rarely deviated from the original numbering system.(D. Yachechak, personal communication, March 1997)
At present, most Class I railroads in the U.S. use one of two “standard” rulebooks: the Northeast Operating Rules Advisory Committee (NORAC) rulebook and the General Code of Operating Rules (GCOR). Conrail, Amtrak, and several commuter and short line railroads in the northeastern United States use the NORAC rulebook. The GCOR is used by every Class I railroad west of the Mississippi River, most of the Class II railroads, and numerous shortline railroads. A few railroads, including CSX, Norfolk Southern, Illinois Central, Metro North and Florida East Coast, have adopted their own rulebooks. In the case of NS and CSX, the NORAC Rulebook was integrated into their existing rulebook structure with the Conrail merger. Metro-North uses a rulebook based on NORAC. The Long Island Rail Road (LIRR) still uses a rule book that is based on the Standard Code of Operating Rules. Canadian railways use the CROR.
Research indicates unsafe work behavior can be influenced by any number of factors, including temperature, workload, time of day, and specific job tasks to name a few.(Ramsey et al., 1983) Unsafe work behavior has also been linked to the organizational culture and to organizational processes.(Andrews, 1997; Marske, 1997) Consequently, before unsafe work behaviors in railroad operations can be reduced, some of the reasons employees do not comply with railroad operating rules must be understood. Also, there must be an understanding of some of the cultural components of rule compliance within the railroad system, particularly the development of railroad rules, and how that culture interacts with unsafe work behavior.
Historic methods of operation Timetable operation All trains must have authority to occupy a main track. Originally possession of a timetable which showed a schedule for that train, authorized a train crew to take their movement onto the main track.
The simplest form of operation, in terms of equipment at least, was operation according to a schedule. Everything was laid down in advance and every train crew knew the timetable. Trains could only operate according to the scheduled time at each station for their train, during which they had exclusive "possession" of the track and no other train could operate on the same track. Trains typically were required to be "clear" of the mainline within five minutes of an opposing or following train's time at the next station. The timetable also specified (usually prominently on the first page) the superiority of trains by direction or class, for example, on most railroads an Eastward train was superior to a Westward train, and a First Class (passenger) train would be superior to a Fourth Class train (freight.) A superior train would normally hold the main track at meeting places, while the inferior train would take the siding on single track territory.
When trains were operating in opposing directions on a single-line railroad, meets were scheduled, where each train waited for the other at a point they could pass. Neither was permitted to move until the other had arrived.
The timetable system had several disadvantages. The first was that there was no positive confirmation that the track ahead was clear; only that it should be clear. This system did not allow for breakdowns and other such problems. The timetable was set up in such a way that there should be sufficient time between trains for the crew of a broken-down or delayed train to walk back up the line far enough to set up warning flags, fusees and explosive devices known as torpedoes, which alerted a train crew to an occupied track ahead.
The second problem was the timetable system's inflexibility; trains could not be added, delayed, or rescheduled without publishing and distributing a new timetable. Trains all down the line might have to stay clear of the main line, waiting for a train which never started from its initial station.
The third was a corollary of the second; the timetable system was inefficient. To give a little flexibility, the timetable gave trains a broad swath of time to allow for some delay. Thus, the line was possessed by the train for much longer than was really necessary.
Nonetheless, this system permitted operation on a vast scale, with no requirements for any kind of communication that travelled faster than a train. Timetable operation was the normal mode of operation on North American railroads in the early days.
Timetable and train order With the advent of the telegraph, a more sophisticated system became possible, since the telegraph provided the first system available where messages could be transmitted faster than the trains themselves. The telegraph allowed the dissemination of alterations to the timetable, known as train orders. These overrode the timetable, allowing the cancellation, rescheduling and addition of trains, and almost anything else. Sufficient time had to be given, however, so that all train crews could receive the changed orders.
Train crews generally received the orders at the next station at which they stop, although sometimes orders were handed up to a locomotive "on the run" via a long staff or hoop. Train orders allowed train dispatchers to set up meets at sidings, force a train to wait at a siding for a priority train to pass from behind, and to keep at least one block spacing between trains going the same direction. Train orders could also reverse the superiority of trains, or give extra or inferior trains rights over superior trains in order to accommodate abnormal operating conditions.
In North American railway traffic control, a Form 19 or 31 train order would modify their schedule. An order which did not require a train to stop was called a "Y" (yellow) train order. The operator at the station would display a Yellow signal, which would cause the train to slow down so that they could receive the train order from a hoop from the operator. These commonly gave crews information about track speed (in areas where tracks and bridges needed repair) and were called "slow orders" by train crews. An "R" (red) order told the station operator to display a red (stop) signal, and dealt with meets, waits and other important traffic control issues, it was necessary for the crews to stop because they often had to sign for them, indicating that they had read and understood the situation. Orders were flagged at train stations by telegraph operators who signaled using a fixed "order board", which usually consisted of a single semaphore blade mounted over the operator's position in the station. The operator usually had to confirm to the dispatcher that the requested Y or R signal had been displayed properly before the dispatcher could issue further instructions to other trains or engines concerning that movement.
Timetable and train order operation was commonly used on American railroads until the 1960s, including some quite large operations such as the Wabash Railroad and the Nickel Plate Road. Train order traffic control was used in Canada until the late 1980s on the Algoma Central Railway and some spurs of the Canadian Pacific Railway. On CN's Deux-Montagnes commuter line, this system lasted on part of the route until the total replacement of signaling and catenary in 1995. The orders were notable for being bilingual.
Timetable and train order was not used widely outside North America and has been phased out in favor of radio dispatching on many light-traffic lines and electronic signals on higher-traffic lines. The only railroads currently still using authentic train order operations is the South Shore line in Indiana and the LIRR in New York.
Modern signaling in the U.S. and Canada
U.S. railroads have historically used a far greater variety of signaling systems than other countries. There have never been national standards for signal appearance and operation, so each of the hundreds of rail lines developed its own signaling techniques.
As Trains magazine describes:
This was no problem as long as crews stayed on home territory. But as roads merged, split, and spun off new short lines, and tenant operators such as Amtrak and regional commuter systems came into existence, train crews could find themselves on several different properties in the course of a work week.
The creation of Conrail in 1976 out of the remains of a half-dozen bankrupt railroads only made things worse. It was hard enough to rationalize the systems of the constituent companies, let alone interact with other operators over the dense Northeastern U.S. rail network.