Railway Signalling and Operations FAQ: Operating Authority

Railway Signalling and Operations

Operating Authority -- North America


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Notes

Incomplete. Additions welcomed.


The authority for operating trains developed and changed over time. The "traditional", AAR-based [American Association of Railroads] rule structure followed this historical development. Newer rules superseded older rules which superseded "default" rules, on specified sections of the railroad. As rule systems have been rewritten in the 1970s-1990s, they have tended to deviate more and more from the original AAR structure. The trend in the newer rule structures is for less and less superseding of one set of rules by another, but rather, of a certain "block" of rules simply being in effect, and another "block" not being in effect.

Timetable Authority

Train separation by time is the oldest means of control. It is also the most difficult, and in some ways, the most complicated. (See PRR Book of Rules, 1857 for an example.) These rules are numbered below 200 and include rules governing superiority of trains, extra trains, hand signals, protection of trains, and so forth.

One of the most important rules is Rule 99, which governs protection of trains:

99. When a train stops under circumstances in which it may be overtaken by another train, a member of the crew must go back immediately with flagging equipment a sufficient distance to insure full protection, placing two torpedoes, and when necessary, in addition, displaying lighted fusees.
When recalled and safety to the train will permit, he may return.
When conditions require, he will leave the torpedoes and a lighted fusee.
The front of the train must be protected in the same way when necessary.
When a train is moving under circumstances in which it may be overtaken by another train, a member of the crew must take such action as may be necessary to insure full protection. By night, or by day when the view is obscured, lighted fusees must be dropped off at proper intervals.
When day signals cannot be plainly seen, owing to weather or other conditions, night signals must also be used.
Conductors and enginemen are responsible for the protection of their trains.
When a pusher engine is assisting a train, coupled behind the cabin car, and the member of the crew that protects the rear end of the train is riding in the cabin car, the requirements as to the use of fusees should be met by dropping them off between the cabin car and pusher engine on the track the train is using, and not between that track and an adjacent track.
Note--When trains are operating under automatic block signal system rules, the requirements of Rule 99 do not apply for following movements on the same track.
Note--When trains are operating under manual block signal system rules, the requirements of Rule 99 will not apply for following movements on the same track where Rule 316 is in effect, except when required by train order or timetable special instructions.

Train Order Authority

Train order rules are numbered beginning at 201. Train orders, of course, supersede the authority of trains running under timetable authority. The first paragraph of Rule 201 is exemplary:
201. For movements not provided for by time-table, train orders will be issued by authority and over the signature of the Superintendent Transportation and only contain information or instructions essential to such movements.

The remaining rules specify in great detail how train orders are to be transmitted from the controlling employee (operator, dispatcher, etc.) to the engineer and conductor so as to provide for safety. A number of standard train order forms, corresponding to common situations requiring train orders, is usually provided in the rulebook. (See PRR Book of Rules, 1956, Forms of Train Orders.)

Signal Authority

Signal rules are numbered beginning at 251. The textual portion of the rules is actually quite brief, comprising 10 or so rules in 3 sets. These are sufficiently important that I will quote at length [from PRR rules, abridged somewhat]. Note that signal rules are in effect only at locations listed in the Employee Timetable/Special Instructions.
Movement of Trains in the Same Direction by Block Signals
251. On portions of the railroad and on designated tracks so specified on the time-table, trains will run with reference to other trains in the same direction by block signals whose indications will supersede the superiority of trains.
254. Except as affected by Rule 251 all Rules for Conducting Transportation remain in force.
Opposing and Following Movement of Trains by Block Signals
261. On portions of the railroad and on designated tracks so specified on the time-table, trains will be governed by block signals whose indications will supersede the superiority of trains for both opposing and following movements on the same track.
262. A train for which the direction of traffic has been established must not move in the opposite direction without proper interlocking or manual block signal indication or train order.
264. Except as affected by Rule 261 all Rules for Conducting Transportation remain in force.
Movement of Trains on Secondary Tracks Where Block Signal System Rules Are in Effect
271. On designated secondary tracks so specified on the time-table, movements of trains will be made on verbal permission of the operator when authorized by the Superintendent Transportation, governed by Block Signal System Rules.
At locations specified on the time-table, fixed signal indication in lieu of verbal permission will be used.
Authority for movement of a train will be recorded at the office of the Superintendent Transportation in book provided therefor.
272. Yard engines working within yard limits must not move beyond those limits without permission of the operator when authorized by the Superintendent Transportation.
273. Except as affected by Rules 271 and 272, all Rules for Conducting Transportation as they apply to main tracks are in effect.

Rules beginning at 280 are pictures or drawings of the forms of signals, along with the meaning of those signals. These rules provide specific information pertaining to the signal aspect -- i.e., they tell the engineer how his action is to be affected at a specific spot, the location of that signal and possibly for some distance beyond -- but they do not cover other eventualities, nor do they cover "overall" operating methods on that portion of track. These specifics are covered, minimally, in Rules 251-[279], but more so in "rule system" rules that follow.

Rule System Rules

Similarly to signal rules, rule system rules [my term] are in effect only on trackage specified in the Employee Timetable/Special Instructions. However, in contrast to signal rules, rule system rules are in effect along with signal rules and do not supersede them (which is why my heading above does not contain the word "authority"). Rule system rules come in several mutually exclusive sets:

Manual Block System [MBS] Rules

Manual block rules are numbered from 301 and comprise a large set of rules. It is apparent, and perhaps reasonable, that anytime manual (i.e., human, pen-and-paper) control of trains is in effect, a large number of rules is needed to govern it. Note Rule 305:
Note--Rules 305 to 373 inclusive will not be effective except by special instructions.
305. Block signals govern the use of the blocks, and except where Rule 251 or 261 is in effect, do not supersede the superiority of trains, nor dispense with the use and the observance of other signals whenever and wherever they may be required.

The remaining rules cover opening and closing of block stations ("towers", "signal boxes"), absolute block working, permissive block working, yard limits, what information is to be given to whom and when, and so forth.

Automatic Block System [ABS] Rules

Automatic block rules are numbered from 501 and, like MBS rules, are in effect by Special Instruction only. For ABS, Rule 251 or 261 were usually, but not always, in effect as well. ABS rules are introduced thus:
501. Block signals, cab signals or both govern the use of the blocks and except where Rule 251 or Rule 261 is in effect, do not supersede the superiority of trains nor dispense with the use and the observance of other signals whenever and wherever they may be required.
Interlocking home signals governing the use of routes leading to a block will in addition govern the use of the block in direction for which traffic has been established for a train to the next block signal.

[Note that the implication is that interlocking signals govern a 'route' within the interlocking, not a block; and that they optionally govern a 'block' beyond the interlocking... as well -MDB]

Following rules cover entering a block between signals, reversing direction, equipment that may not shunt the track, and operating against the current of traffic.

Traffic Control System [TCS] Rules

Now renamed "CTC rules" on some railroads. ...

Cab Signal System [CSS] Rules

Cab signal rules are numbered from 551 and generally supplement ABS, TCS, and interlocking rules. They are in effect only at locations specified in the Special Instructions. The rules cover the expected operation of the cab signal apparatus, frequency of testing, cab signal aspect 'flips' [transient changes of aspect], and non-correspondence of the cab signal aspect with the fixed (wayside) signals. (The expected cab signal aspect, given the fixed signal aspect, is listed with the signal rule diagrams, Rules 280 and up.)

Interlocking Rules

Interlocking rules are numbered from 601 and govern movements within the limits of an interlocking. Interlocking limits are defined by the locations of their home signals, which must be absolute signals. Most interlocking signals are controlled (by humans); at automatic interlockings, i.e. interlockings that operate autonomously, the interlocking signals are controlled only by local circuitry, the signal clearing being initiated by the approach of a train into the approach circuitry.
605. Interlocking signals govern the use of the routes of an interlocking, and as to movements within interlocking limits that are protected by home signals and distant signals, their indications supersede the superiority of trains, and engine and train crews are relieved from observing Rule 99 and Rule 152. Movements against the current of traffic beyond home signal limits must not be made except under flag protection.

The remaining rules pertain in large part to the operator's duties, with some additional rules governing trains. In particular are a rule about delay of the train in the approach block (the engineer must then approach the home signal prepared to stop) and another allowing reverse movements on signal indication, i.e., without train order. Of note, particularly in contrast to British working, is a rule requiring a stop "clear of an interlocking signal indicating Stop".

Absolute-Permissive Block Rules

This may or may not have been a separate set. I'll have to dig out some old Conrail rules/timetables ...


Comments, Apparent Contradictions

Signal Rules Without Rule 251/261

[Jon Roma] The authority to operate was the timetable schedule and a clearance card issued at your initial point on the subdivision. And in the case of an extra, IC's rules allowed an extra train (other than a work extra) to be authorized by clearance on double track.

To add a little light to this, the reason an extra on single track needs orders is that the extra needs to be protected against any opposing extras. Since extras aren't in the timetable, the extras need to be known to each other and a meeting point needs to be set.

On double track, there are no opposing trains one needed to protect if present or by a 10-minute spacing rule otherwise. And by flagging if necessary. This is why extras on double track don't need to be created with a running order.

Cab Signals Without Fixed Wayside Signals

In some locations (interestingly, increasing numbers of locations in the 1990s), cab signals were used without fixed wayside signals. In such locations, CSS rules were in effect, and ABS or TCS rules were as well, except that there were no block (automatic, non-interlocking) signals. Interlocking signals remained.


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Mark D. Bej, M.D.
+216-444-0119
1997.05.31