Signal and Train ControlRULES, STANDARDS, AND INSTRUCTIONS (R,S&I)

STC – F

Dragging Equipment and Slide Detectors and Other Similar Protective Devices

Subpart F

Dragging Equipment and Slide Detectors and Other Similar Protective Devices

§ Signals controlled by devices used to provide protection against unusual contingencies, such as landslides, dragging equipment, burned bridges or trestles and washouts shall be located so that stopping distance will be provided between the signal and the point where it is necessary to stop the train. 

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Learning Objectives
        - Understand that these regulations are engineering design standards and must be incorporated into the design of any on-board signal system.
        - Understand that actions taken during the installation, maintenance, or modification of the system must not negate these design standards.	

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The purpose of a on-board signal systems is to enhance operational safety by trapping human errors before there are catastrophic consequences.  To accomplish this purpose the system must be designed and maintained to the standard outlined in Subpart E.

CAUTION

The following presentation was developed to provide general information only. For detailed compliance information please refer to 49 CFR 236 – Rules, Standards and Instructions, Subpart E and the S&TC technical manual.  It is recommended that each employee refer to appropriate manuals and regulations when dealing with any specific issue.

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When in doubt, go to the book!

Information

The FRA Rules, Standards, and Instructions are considered to be the minimum standard allowed for the installation, inspection, maintenance, and repair of signal and train control systems, devices, and appliances.  Each railroad may adopt more stringent standards. Refer to your railroad’s signal standard and instruction manual for further guidance.

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236.601 Signals controlled by devices; location.

Signals controlled by devices used to provide protection against unusual contingencies, such as landslides, dragging equipment, burned bridges or trestles and washouts shall be located so that stopping distance will be provided between the signal and the point where it is necessary to stop the train.
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This rule requires that signals controlled by devices to protect against unusual contingencies, such as landslides, dragging equipment, washouts, etc., shall be located so that stopping distance will be provided between the signal and the point where it is necessary to stop the train.

This rule is applicable to all signals or systems governing the movement of trains into one or more blocks that are not covered in Subparts B, C, D, and E of Part 236.

Part 236, Subpart A, contains the applicable sections to use when citing defective conditions of devices or systems covered by this rule.

Such protective devices are installed as safety features and shall not be removed without approval of FRA unless the condition that warranted their installation ceases to exist.  If for some reason the signals or devices are removed from service for a temporary period the carrier shall take appropriate measures to protect safety of train operation.

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Dragging Equipment Detector

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Standards

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Following are the standards to which all traffic control systems must be designed, installed, tested, and maintained.

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236.501   Forestalling device and speed control.
        - May be included as part of an ATS or ATC system.
        - Sometimes referred to as an “Acknowledging Device”.
        - Dictates speed control features for Low-speed, Medium speed, and Maximum speed restrictions.

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This rule permits the use of a forestalling device in automatic train stop systems and sets forth the minimum requirements for control of speed in automatic train control systems.

Applies to automatic train stop and train control systems.

An automatic train stop system may, but is not required to, include an acknowledging device by means of which the automatic application of the brakes can be forestalled.

An automatic train control system is required to have one or more of the following features:

(1)	A low-speed restriction, effective as long as the condition that causes the restriction exists, that prohibits movement exceeding slow speed either after the train has been stopped by automatic application of the brakes or its speed reduced to slow speed by manual application of the brakes.

(2)	A medium-speed restriction that, in order to prevent an automatic application of the brakes, requires the train to proceed under medium speed after passing a signal displaying an approach aspect, or when approaching a signal requiring a stop, or a stop indication point.

(3)	A maximum-speed restriction that will effect an automatic brake application whenever the predetermined maximum authorized speed is exceeded.

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Forestalling Definition

§ 236.747 Forestall.

As applied to an automatic train stop or train control device, to prevent an automatic brake application by operation of an acknowledging device or by manual control of the speed of the train. 

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Forestalling feature allows engineer or operator to forestall the penalty brake application and manually control the speed of the train.

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Medium &Slow Speed Definition

§ 236.811 Speed, medium.

A speed not exceeding 40 miles per hour. 

§ 236.813 Speed, slow.

A speed not exceeding 20 miles per hour. 

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The speeds imposed by the slow speed or medium speed restrictions must comply with the carrier's definition of slow speed or medium speed which may not exceed that defined by Rules 236.813 or 236.811, respectively, without approval of FRA.  Each carrier establishes its own maximum speed.

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236.502  Automatic brake application, initiation by restrictive block conditions stopping distance in advance.

This is a companion rule to Rule 236.504 and requires that the automatic brake application be initiated at least stopping distance from the entrance of a block where any condition exists as described in Rule 236.205. 

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As Reference:

§ 236.205 Signal control circuits; requirements.

The circuits shall be so installed that each signal governing train movements into a block will display its most restrictive aspect when any of the following conditions obtain within the block: 

(a) Occupancy by a train, locomotive, or car, 

(b) When points of a switch are not closed in proper position, 

(c) When an independently operated fouling point derail equipped with switch circuit controller is not in derailing position, 

(d) When a track relay is in de-energized position or a device which functions as a track relay is in its most restrictive state; or when signal control circuit is de-energized. 

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236.502  Automatic brake application, initiation by restrictive block conditions stopping distance in advance.

ABS Territory with ATC or ATS

Safe Braking Distance

Broken Rail

If engineer does not acknowledge or comply with speed rules, system must initiate brake application.

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Applies to automatic train stop and train control systems.

This rule requires that an automatic train stop or train control system be so arranged that it will operate to initiate an automatic brake application at least stopping distance in approach to a block wherein any condition described in Rule 236.205 exists and at each main track signal requiring a reduction in speed.

This rule is applicable to signals governing movements on or onto the main track.  Signals on auxiliary tracks and sidings, whether signaled or non-signaled, are exempt from the requirements of this rule.

236.503  Automatic brake application; initiation when predetermined rate of speed exceeded.

An automatic train control system shall operate to initiate an automatic brake application when the speed of the train exceeds the predetermined rate as required by the setting of the speed control mechanism.

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This is a companion rule to Section 236.501 and requires overspeed protection of all restrictive features used in automatic train control systems.

Applies to automatic train control systems only.  This rule requires that automatic train control apparatus function to initiate an automatic brake application whenever the speed of the train exceeds any predetermined setting of the speed control mechanism.  A tolerance of 3 miles per hour is permitted in excess of the predetermined setting of the speed control mechanism.

236.504  Operation interconnected with automatic block-signal system. 

(a) A continuous inductive automatic train stop or train control system shall operate in connection with an automatic block signal system and shall be so interconnected with the signal system as to perform its intended function in event of failure of the engineer to acknowledge or obey a restrictive wayside signal or a more restrictive cab signal.

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This rule prescribes the interconnection and operation of an automatic train stop or train control system with a wayside block signal system.

Applies to automatic train stop and train control systems.

This rule requires that an automatic train stop or train control system operate in connection with an automatic block signal system.  The train stop or train control system must be so interconnected with the signal system that it will impose an automatic application of the brakes in event the engineman fails, (1) to obey or acknowledge the indication of a cab signal requiring a reduction in speed in a continuous inductive automatic train stop or train control system; or (2) to acknowledge a restrictive wayside signal in an intermittent automatic inductive train stop system.

236.504  Operation interconnected with automatic block-signal system. 

(b) An intermittent inductive automatic train stop system shall operate in connection with an automatic block signal system and shall be so interconnected with the signal system that the failure of the engineer to acknowledge a restrictive wayside signal will cause the intermittent inductive automatic train stop system to perform its intended function.

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This rule is applicable only to those signals governing movements on or onto the main track. 

Signals on auxiliary tracks are exempt from the requirements of this rule.

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236.505  Proper operative relation between parts along roadway and parts on locomotive. 

Applies to automatic cab signal, train stop and train control systems.

This rule requires that apparatus on locomotives and at wayside locations be properly interconnected and function as intended regardless of speed, weather, wear, oscillation or shock. 

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The functionality between wayside equipment and  on-board equipment must be  maintained regardless of environmental conditions.

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236.506  Release of brakes after automatic application.

This rule prescribes the conditions under which the brakes may be released following an automatic brake application.

An intermittent inductive automatic train stop system shall not permit release of the brakes following an automatic brake application until after the train has been stopped.

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Applies to automatic train stop and train control systems.

Once a penalty application of brakes has been initiated in intermittent train stop territory the brakes are not allowed to be released until a complete stop has been achieved.

A continuous inductive automatic train stop system shall not permit release of the brakes following an automatic brake application until after the train has been stopped, unless the condition that caused the brake application no longer exists.

An automatic train control system shall not permit release of the brakes following an automatic brake application until the speed has been reduced to a predetermined rate or until the train has been stopped unless the condition that caused the brake application no longer exists.

This rule prohibits use of a reset device in the control compartment that, when operated, permits release of the brakes before the train has been stopped.

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236.507  Brake application; full service.

Applies to automatic train stop and train control systems.

This rule requires that an automatic train stop or train control brake application be a full service brake application as defined by Rule 236.701.  The imposition of an emergency brake application is prohibited. 

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§ 236.507   Brake application; full service.

The automatic train stop or train control apparatus shall, when operated, cause a full service application of the brakes.

This rule, in conjunction with 236.502 - Automatic brake application, initiation by restrictive block conditions stopping distance in advance, ensure that a train receiving a restricting signal aspect will have adequate distance to make a safe stop using a full service application of the train air brakes.

Full Service Brake Application Definition

§ 236.701 Application, brake; full service.

An application of the brakes resulting from a continuous or a split reduction in brake pipe pressure at a service rate until maximum brake cylinder pressure is developed. As applied to an automatic or electro-pneumatic brake with speed governor control, an application other than emergency which develops the maximum brake cylinder pressure, as determined by the design of the brake equipment for the speed at which the train is operating. 

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236.508  Interference with application of brakes by means of brake valve.

Applies to automatic cab signal, train stop and train control systems.

This rule prohibits the installation and use of apparatus that interferes with the manual application of the brakes by means of the independent or automatic brake valves or that impairs the efficiency of the air brake or blended brake system when operated manually.

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§ 236.508   Interference with application of brakes by means of brake valve.

	The automatic train stop, train control, or cab signal apparatus shall be so arranged as not to interfere with the application of the brakes by means of the brake valve and not to impair the efficiency of the brake system.

In other words,  the automatic train stop, train control, or cab signal apparatus must not interfere with or impair the efficiency of the locomotive braking system. 

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236.509  Two or more locomotives coupled. 

Applies to automatic cab signal, train stop and train control systems.

When two or more equipped locomotives are coupled together, or a pushing or helping locomotive is used, the automatic train stop, train control or cab signal apparatus affecting movement of that train must be so arranged that it is operative only on the locomotive from which the brakes are controlled. 

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§ 236.509   Two or more locomotives coupled.

The automatic train stop, train control or cab signal apparatus shall be arranged so that when two or more locomotives are coupled, or a pushing or helping locomotive is used, it can be made operative only on the locomotive from which the brakes are controlled.

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236.509  Two or more locomotives coupled. 

The automatic train stop, train control or cab signal apparatus affecting movement of the train must be so arranged that it is operative only on the locomotive from which the brakes are controlled.

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236.511  Cab signals controlled in accordance with block conditions stopping distance in advance.

Applies to automatic cab signals.

Cab signals are required to be continuously controlled to indicate that speed is to be restricted and stop may be required at least stopping distance to all conditions described in Rule 236.205.

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This rule requires that ACS will indicate the speed is to be restricted when any of the following conditions obtain within the block: 

(a) Occupancy by a train, locomotive, or car, 

(b) When points of a switch are not closed in proper position, 

(c) When an independently operated fouling point derail equipped with switch circuit controller is not in derailing position, 

(d) When a track relay is in de-energized position or a device which functions as a track relay is in its most restrictive state; or when signal control circuit is de-energized. 

Conditions that cause wayside false restrictive aspects such as open or crossed light circuit conductors or burned out lamp bulbs, except where light-out protection is provided, are exempt from these requirements.

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236.512  Cab signal indication when locomotive enters block where restrictive conditions obtain. 

This rule requires that the cab signal indicate "Proceed at Restricted Speed" when the locomotive enters or is within a 

block in cab signal 

territory wherein a 

condition described 

in Rule 236.205 

exists.

Restricted Speed Indication

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Cab signal must indicate “Proceed at Restricted Speed” if any of the following conditions exist:

§ 236.205 Signal control circuits; requirements.

The circuits shall be so installed that each signal governing train movements into a block will display its most restrictive aspect when any of the following conditions obtain within the block: 

(a) Occupancy by a train, locomotive, or car, 

(b) When points of a switch are not closed in proper position, 

(c) When an independently operated fouling point derail equipped with switch circuit controller is not in derailing position, 

(d) When a track relay is in de-energized position or a device which functions as a track relay is in its most restrictive state; or when signal control circuit is de-energized. 

Rule 236.514 permits the cab signal to change to a more favorable aspect after the train has passed the condition that exists or if the condition ceases to exist. 

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236.513  Audible indicator. 

Applies to automatic cab signal, train stop, and train control systems.

This rule requires an audible indicator be provided in cab signal systems and so arranged that it will sound continuously, until silenced by manual operation of an acknowledging device, when the cab signal changes to display a more restrictive aspect.  

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Applies to automatic cab signal, train stop, and train control systems.

The audible indicator may be electrically or pneumatically operated and must have a distinctive sound that identifies it with the system and be clearly audible through the cab under all operating conditions.  The audible indicator may be so arranged that it will sound continuously during an overspeed condition and silenced only by reducing to proper speed.

Methods to silence or muffle the cab indicator such a wrapping or plugging with paper or cloth or bending or breaking the air pipe to reduce air flow are prohibited.  If such tampering with this safety device is found, refer to Section 218.55.  Any individual who willfully disables or nullifies a safety device is subject to a civil penalty as provided in appendix A of this part, and to disqualification from performing safety-sensitive functions on a railroad if found unfit for such duties under the procedures provided for in 49 CFR Part 209.

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236.514  Interconnection of cab signal system with roadway signal system.

This rule requires the locomotive cab signal apparatus be so interconnected to the wayside signals system that it will not authorize operation at a speed higher than that authorized by the wayside signal indication except when conditions affecting the movement of trains in a block change after the train passes the wayside signal.

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Applies to automatic cab signal systems.

These requirements apply to all signaled track, including signaled sidings and signaled auxiliary tracks, in automatic cab signal territory.

236.515  Visibility of cab signals. 

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The cab signals shall be plainly visible to member or 

members of the

locomotive crew

from their 

stations in the 

cab.

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This rule requires that the cab signal be so located that the locomotive crew member or members can plainly see the aspect.

Applies to automatic train stop, train control, and cab signal systems.

Cab signals are required to be so installed that the crew member or members can plainly see the aspect displayed from their accustomed positions in the cab.

The cab signal is required to be properly illuminated, without cracked or broken roundels and its view not obstructed by other equipment installed in the cab.  If tampering with this safety device is found, refer to Section 218.55.  Any individual who willfully disables or nullifies a safety device is subject to a civil penalty as provided in appendix A of this part, and to disqualification from performing safety-sensitive functions on a railroad if found unfit for such duties under the procedures provided for in 49 CFR Part 209.

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236.516  Power supply.

Automatic cab signal, 

train stop, or train control 

device hereafter installed 

shall operate from a 

separate or isolated 

power supply.

Devices installed on locomotive prior to the effective date of these RS&I are exempt from this requirement.   (prior to February 27, 1984 )

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This rule requires that each automatic train stop, train control, or cab signal device hereafter installed on a locomotive operate from a separate or isolated power supply.

Applies to automatic train stop, train control, and cab signal systems.

The rule requires that the automatic train stop, train control, or cab signal device be provided with a dedicated power supply used solely to operate the device.  It is prohibited to utilize the power supply to provide power to any other device or system.

Devices installed on locomotive prior to the effective date of these RS&I are exempt from this requirement.

Rules and InstructionsRoadway

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236.526  Roadway element not functioning properly. 

Applies to automatic train stop, train control, and cab signal systems.

This rule requires that when a roadway element such as a tripper, inductor, loop, or electric circuit, except track circuit, becomes defective or is being repaired or replaced, the signal associated with the device must be manually caused to display its most restrictive aspect.

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This rule requires that when the roadway element, except track circuit, of an automatic train stop, train control, or cab signal system has failed to perform its intended function, the associated signal shall be caused manually to display the most restrictive aspect.

§ 236.526   Roadway element not functioning properly.

	When a roadway element except track circuit of automatic train stop, train control or cab signal system is not functioning as intended, the signal associated with such roadway element shall be caused manually to display its most restrictive aspect until such element has been restored to normal operative condition.

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236.527  Roadway element insulation resistance. 

Applies to intermittent inductive automatic train stop systems.  This rule applies only to the roadway inductor winding.  The insulation resistance of cable or conductors that connect the inductor to its associated signal must comply with the requirements of Rule 236.108.

Disconnect the coil wires and test each to ground.  Insulation resistance between roadway inductor winding and ground must not be less than 10,000 ohms.

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This rule requires insulation resistance between roadway inductor winding and ground shall be maintained at not less than 10,000 ohms.

Applies to intermittent inductive automatic train stop systems.

Disconnect the coil wires and test each to ground.  Do not test the coils against each other with an insulation resistance tester.

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236.528  Restrictive condition resulting from open hand-operated switch; requirement. 

Applies to continuous inductive automatic train stop, train control and cab signal systems.

This rule requires that switch shunting circuits or switch repeating circuits of hand-operated switch or facing-point lock with circuit controller effectively shunt the track circuit or open the signal control circuits to the extent...

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§ 236.528   Restrictive condition resulting from open hand-operated switch; requirement.

	When a facing point hand‐operated switch is open one‐fourth inch or more, a trailing point hand‐operated switch three‐eighths inch or more, or hand‐operated switch is not locked where facing point lock with circuit controller is used, the resultant restrictive condition of an automatic train stop or train control device of the continuous type or the resultant restrictive cab signal indication of an automatic cab signal device on an approaching locomotive shall be maintained to within 300 feet of the points of the switch.

This rule requires that the restrictive condition of continuous inductive automatic train stop or train control device or restrictive cab signal indication of an automatic cab signal device be maintained to within 300 feet of an open hand-operated switch or unlocked facing-point lock in equipped territory.

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236.528  Restrictive condition resulting from open hand-operated switch; requirement. 

Some “track current leakage” may be present beyond the open switch, however the shunted track circuit must maintain the restrictive cab condition to within 300 feet.

Track Energy

Track E~I Curve

Restricted

Indication

300

Feet

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This rule requires that switch shunting circuits or switch repeating circuits of hand-operated switch or facing-point lock with circuit controller effectively shunt the track circuit or open the signal control circuits to the extent that the restrictive condition of continuous inductive automatic train stop or train control device or restrictive aspect of cab signal device of an approaching locomotive is maintained to within 300 feet of a facing-point switch opened one-fourth inch or more, a trailing point switch opened three-eights inch or more, or, a facing-point lock that is not locked.

Foreign Current Definition

§ 236.733 Current, foreign.

A term applied to stray electric currents which may affect a signaling system, but which are not a part of the system. 

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236.529  Roadway element inductor; height and distance from rail. 

 This rule requires that the inductor pole faces be maintained at a height above the plane of the tops of the rails with its inner edge at a horizontal distance from the gage side of the nearest running rail in accordance with the carrier's specifications. 

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Applies to intermittent inductive automatic train stop systems.

This rule requires that inductors of the inert roadway type be installed and maintained in position in accordance with specifications of the carrier.

§ 236.529   Roadway element inductor; height and distance from rail.

Inductor of the inert roadway element type shall be maintained with the inductor pole faces at a height above the plane of the tops of the rails, and with its inner edge at a horizontal distance from the gage side of the nearest running rail, in accordance with specifications of the carrier.

Roadway Element Definition

§ 236.744 Element, roadway.

That portion of the roadway apparatus of automatic train stop, train control, or cab signal system, such as electric circuit, inductor, or trip arm to which the locomotive apparatus of such system is directly responsive. 

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236.531  Trip arm; height and distance from rail. 

Trip arm of automatic train stop device when in the stop position shall be maintained at a height above the plane of the tops of the rails, and at a horizontal distance from its center line to gage side 

of the nearest running 

rail, in accordance with 

specifications of the 

carrier.

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This rule requires that trip arm of automatic train stop device, when in stop position, be installed and maintained in position in accordance with specifications of the carrier.

Applies to mechanical trip type automatic train stop system.

This rule requires that trip arm, when in stop position, be maintained at a height above the plane of the tops of the rails with its centerline at a horizontal distance from the gage side of the nearest running rail in accordance with the carrier's specifications.

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236.532  Strap iron inductor; use restricted. 

Applies to intermittent inductive automatic train stop system.

The use of strap iron inductors or other roadway element with characteristics differing from its standard type is prohibited on track where speed higher than 20 mph is permitted. 

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§ 236.532   Strap iron inductor; use restricted.

	No railroad shall use strap iron inductor or other roadway element with characteristics differing from its standard type on track where speed higher than restricted speed is permitted.

This rule restricts the use of strap iron inductors or other roadway element with characteristics different from its standard type.

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236.534  Entrance to equipped territory; requirements. 

Applies to automatic train stop, train control, and cab signal systems.

This rule requires that automatic train stop, train control, or cab signal device be operative at least stopping distance from the entrance to equipped territory except...

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 This rule requires that automatic train stop, train control, or cab signal device be operative at least stopping distance from the entrance to equipped territory except: 
          - Where trains are required to stop at the entrance to equipped territory, or 
          - The approach thereto is governed by an operative approach signal, or 
          - When leaving yards and stations where speed until entering equipped territory does not exceed restricted speed.

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236.534  Entrance to equipped territory; requirements. 

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This rule requires that where trains are not required to stop at the entrance to equipped territory, except when leaving yards and stations and speed until entering equipped territory does not exceed restricted speed, the automatic train stop, train control, or cab signal device shall be operative at least stopping distance from the entrance to such territory except where the approach thereto is governed by automatic approach signal.

Applies to automatic train stop, train control, and cab signal systems.

This rule requires that automatic train stop, train control, or cab signal device be operative at least stopping distance from the entrance to equipped territory except where trains are required to stop at the entrance to equipped territory, or the approach thereto is governed by an operative approach signal, or when leaving yards and stations where speed until entering equipped territory does not exceed restricted speed.

Rules and InstructionsLocomotive

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236.551   Power supply voltage; requirement.

The voltage of power supply shall be maintained within 10 percent of rated voltage.

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This rule prescribes the tolerance within which the power supply voltage shall be maintained.

Applies to automatic train stop, train control, and cab signal systems.

The voltage of the power supply must be maintained to within 10 percent of the rated voltage.

This applies to the isolated power supply as required by 236.516.

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236.552   Insulation resistance; requirement.

When periodic test prescribed in 236.588 is performed, insulation resistance between wiring and ground of continuous inductive automatic cab signal system, automatic train control system, or automatic train stop system shall be not less than ... 

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Applies to automatic train stop, train control, and cab signal systems.

This rule prescribes the minimum insulation resistance permitted between wiring and ground.
          -  The insulation resistance between wiring and ground of continuous inductive automatic train stop, train control and cab signal systems shall be not less than one (1) megohm when periodic test is performed and not less than 250,000 ohms between periodic tests.
          - The insulation resistance between wiring and ground of intermittent inductive automatic train stop system shall be not less than 250,000 ohms when periodic test is performed and not less than 20,000 ohms between periodic tests.

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236.553   Seal, where required.

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Seal shall be maintained on any device other than brake‐pipe cut‐out cock (double‐heading cock), by means of which the operation of the 

pneumatic portion of 

automatic train‐stop 

or train‐control apparatus 

can be cut out.

This rule requires that a seal be maintained on any device other than brake pipe cutout cock (double heading cock), by means of which the operation of pneumatic portion of automatic train stop or train control apparatus can be cut out.

Applies only to automatic train stop and train control systems.  Does not apply to automatic cab signal systems.

This rule requires that automatic train stop or train control apparatus be cut in and a seal applied to any device or cutout cock, except double heading cock, by means of which any part of the pneumatic portion of the apparatus can be cut out.  The seal is required to be applied in such a manner that the device cannot be operated to cut out the apparatus without breaking the seal.

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236.554   Rate of pressure reduction; equalizing reservoir or brake pipe.

The equalizing‐reservoir pressure or brake‐pipe pressure reduction during an automatic brake application shall be at a rate not less than that which results from a manual service application.

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This is a companion rule to Section 236.507 and requires that the equalizing reservoir pressure or brake pipe pressure reduction during an automatic brake application be at a rate not less than that which results from a manual service application.

Applies to automatic train stop and train control systems.

An automatic full service brake application is accomplished by piping and venting arrangements different than that accomplished manually.  This rule requires that the efficiency of the automatic brake application be at least equal to the efficiency of the manual application of the brakes.

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236.555   Repaired or rewound receiver coil.

This rule requires receivers to be rewound with the same size wire and number of turns to achieve the resistive value 

and inductance it originally 

possessed or as currently 

specified for new equipment.  

The rule prohibits repair of 

receivers by removing turns of 

wire to eliminate shorts or opens.

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This rule requires that a receiver coil which has been repaired or rewound have the same operating characteristics which it possessed originally or as currently specified for new equipment.

Applies to automatic cab signal, train stop, and train control systems.

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236.556   Adjustment of relay.

This rule prohibits the adjustment of a relay elsewhere than in a shop equipped for that purpose except when receiver coils, electro-pneumatic valve or other essential part of the equipment is replaced.

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Applies to automatic cab signal, train stop, and train control systems.

This rule requires that adjustment of relay be made only in a shop equipped for that purpose except when receiver coils, electro-pneumatic valve or other essential part of the equipment is replaced.  The rule prohibits adjustment of the relay to compensate for irregularities in power supply voltage or other variable factors in its circuit.

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236.557   Receiver; location with respect to rail.

This rule requires that the receiver of an intermittent inductive automatic train stop device or the receiver of a continuous inductive automatic train stop, train control, or cab signal device on locomotive equipped with onboard test device be maintained in accordance with specifications of the carrier.

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Applies to all intermittent inductive automatic train stop systems and to those continuous inductive automatic train stop, train control, or cab signal devices that are installed on locomotives equipped with onboard test device.

This rule requires that the receiver of covered devices be maintained with bottom of the receiver at a height above the plane of the tops of the rails and with its outer edge at a horizontal distance from the gage side of the nearest rail in accordance with specifications of the carrier.

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236.560   Contact element, mechanical trip type; location with respect to rail.

This rule requires that the contact element of automatic train stop device 

of the mechanical trip type be 

maintained in accordance 

with specifications of the 

carrier.

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236.562   Minimum rail current required.
        - This rule requires that the minimum pick-up value of the locomotive apparatus be maintained in accordance with specifications of the carrier. 
        - Applies to continuous inductive automatic cab signal, train stop, and train control systems.

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§ 236.562   Minimum rail current required.

	The minimum rail current required to restore the locomotive equipment of continuous inductive automatic train stop or train control device to normal condition or to obtain a proceed indication of automatic cab signal device (pick‐up) shall be in accordance with specifications of the carrier.

Applies to continuous inductive automatic cab signal, train stop, and train control systems.

This rule requires that minimum rail current required to restore the locomotive equipment of continuous inductive automatic train stop or train control device to normal condition, or to obtain a proceed indication of automatic cab signal device be in accordance with specifications of the carrier.

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236.563   Delay time.

Delay time of automatic train stop or train control system shall not exceed 8 seconds and the spacing of signals to meet the requirements of 236.24 shall take into consideration the delay time.

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This rule prescribes that the delay time of automatic train stop or train control system not exceed 8 seconds and that the spacing of signals to meet the requirements of Rule 236.24 take into consideration the delay time.

Applies to both intermittent inductive and continuous inductive automatic train stop and train control systems.

Delay time is provided to give the engineer enough time to take proper action to prevent an automatic brake application.  This rule prohibits the delay time from exceeding 8 seconds before the brakes begin to apply.  The rule also requires that spacing of signals in equipped territory include the distance traveled at maximum authorized speed for 8 seconds in order that trains may be stopped by the automatic brake application at the signal where a stop is required, or by reduction in speed to the rate prescribed by the next signal in advance where reduced speed is required.

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Delay Time Definition

§ 236.831 Time, delay.  

As applied to an automatic train stop or train control system, the time which elapses after the onboard apparatus detects a more restrictive indication until the brakes start to apply.

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236.564   Acknowledging time.
        - This rule prescribes that the acknowledging time of intermittent automatic train stop device not exceed 30 seconds.
        - Applies only to intermittent inductive automatic train stop systems.

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Acknowledging time is provided in order to furnish the engineer an ample time period to forestall an automatic brake application by holding the acknowledging lever in reverse position while the locomotive passes a restricting signal.  This rule prohibits the acknowledging lever from being held in the acknowledging position longer than 30 seconds before the brakes start to apply.

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Acknowledging Time Definition

§ 236.830  Time, acknowledging.  

As applied to an intermittent automatic train stop system, a predetermined time within which an automatic brake application may be forestalled by means of an acknowledging device."

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236.565   Provision made for preventing operation of pneumatic brake-applying apparatus by double-heading cock; requirements.

This rule requires that where provision is made for preventing the operation of the pneumatic brake-applying apparatus of an automatic train stop or train control device when the double-heading cock is placed in double-heading position, the double-heading cock shall be so arranged that the automatic brake valve is cut out in advance of or simultaneously with the train stop or train control apparatus

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Applies to automatic train stop and train control systems.

This rule prohibits operation of the double-heading cock to the extent that the automatic train stop or train control pneumatic apparatus is rendered inoperative before the automatic brake valve.

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Double Heading Cock Definition

§ 236.729 Cock, double heading.

A manually operated valve by 

means of which the control of 

brake operation is transferred 

to the leading locomotive. 

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236.566   Locomotive of each train operating in train stop, train control or cab signal territory; equipped.

This rule requires that the locomotive, from which brakes are controlled, of each train operating in automatic train stop, train control, or cab signal territory shall be equipped with apparatus responsive to the roadway equipment installed on all or any part of the route traversed, and such apparatus shall be in operative condition.

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Applies to automatic cab signal, train stop, and train control systems.

This rule requires that each locomotive from which the brakes are controlled which traverses automatic train stop, train control, or cab signal territory be equipped with apparatus responsive to the roadway equipment installed on all or any part of the route traversed.  The rule further requires that the apparatus of the locomotive be in operative condition upon departure from its initial terminal.

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236.567   Restrictions imposed when device fails and/or is cut out en route.

The locomotive from which brakes are controlled, of each train operating in automatic train stop, train control, or cab signal territory shall be equipped with apparatus responsive to the roadway equipment installed on all or any part of the route traversed, and such apparatus shall be in operative condition.

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This rule sets forth the procedures and restrictions that shall be followed when an automatic train stop, train control, or cab signal device fails and/or is cut out en route.

Applies to automatic cab signal, train stop, and train control systems.

This rule requires that when an automatic cab signal, train stop or train control, device fails or is cut out en route the train shall proceed not exceeding 20 miles per hour, or, if an automatic block signal system is in operation, according to signal indication not exceeding 40 miles per hour, to the next available point of communication where a report must be made to a designated officer.  Radio communications are permissible for this purpose.

Following the required report, in the event the train is in territory in which an automatic block signal system is not in use, the train may be permitted to proceed at not exceeding 20 miles per hour to a point where an absolute block is established.  In the event an automatic block signal system is in operation in the territory in which the train is operating, the train may be permitted to proceed according to signal indication at not exceeding 40 miles per hour to a point where an absolute block is established.

An absolute block may be established in both signaled and non-signaled territory by use of manual block rules, train orders, track warrants, or other method of train operation, defined by the carrier's operating rules.  An absolute block may also be established in block signal territory by designating in the carrier's operating rules, that when an onboard train stop or train control device fails, all wayside signals displaying "restricting" or "stop and proceed" aspects will be considered to be displaying a "stop" aspect for the train with the failed device. Thus, an absolute block will essentially be established in front of that train.

Upon establishment of an absolute block in front of the train with the inoperative device, the train may then proceed at speeds not in excess of 79 miles per hour.

The carrier's operating rules shall effect these requirements. 

§ 236.567   Restrictions imposed when device fails and/or is cut out en route.

Where an automatic train stop, train control, or cab signal device fails and/or is cut out en route, train may proceed at restricted speed or if an automatic block signal system is in operation according to signal indication but not to exceed medium speed, to the next available point of communication where report must be made to a designated officer.  Where no automatic block signal system is in use train shall be permitted to proceed at restricted speed or where automatic block signal system is in operation according to signal indication but not to exceed medium speed to a point where absolute block can be established.  Where an absolute block is established in advance of the train on which the device is inoperative train may proceed at not to exceed 79 miles per hour.

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Absolute Block Definition

§ 236.709 Block, absolute.

A block in which no train is permitted to enter while it is occupied by another train. 

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236.568   Difference between speeds authorized by roadway signal and cab signal; action required.

The rule requires that in the event a cab signal authorizes a speed different from that authorized by a roadway signal, the most restrictive speed shall not be exceeded.

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Applies to continuous inductive automatic cab signal, train stop, and train control systems.

This rule requires that if for any reason a cab signal authorizes a speed different from that authorized by a roadway signal, when a train enters the block governed by the signal, the lower speed shall not be exceeded.

The carrier's operating rules shall effect this requirement.

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Inspection and TestsRoadway

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236.576   Roadway element.

This rule requires that roadway elements, except track circuits, including those for test purposes, shall be gaged monthly for height and alinement, and shall be tested at least once every 6 months.

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Applies to automatic train stop systems.

This rule requires that inductor of the inert roadway type and trip arm be gaged monthly for height and alinement.  The rule further requires testing of inductor for defective conditions in its winding or external controlling circuit and of trip arm valves and return springs every six months.

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236.577   Test, acknowledgment and cut-in circuits.

This rule requires that test, acknowledgment and cut-in circuits shall be tested at least once every twelve months.

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Applies to automatic cab signal, train stop, and train control systems.

This rule requires test at least once every twelve months of test circuits, including test equipment, acknowledgment and cut-in circuits.

An acknowledgment circuit is installed between the track rails at each signal or stop indication point in territory where an automatic train stop system of the continuous inductive type with two-indication cab signals is in service, to enforce acknowledgment by the engineer of restrictive conditions in order to forestall an automatic brake application.  The acknowledgment circuit is required to be continuously energized and, if interrupted, it must deenergize its associated track circuit.

A cut-in circuit is a roadway circuit located at the entrance of equipped territory by means of which locomotive equipment of continuous inductive type system is actuated so as to be in an operative condition.  The cut-in circuit shall be so arranged that it requires acknowledgment by the engineer of all restrictive features provided by the device.

Test circuits, including portable and onboard test equipment, may be used for performing the prescribed tests of apparatus on equipped locomotives.

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Inspection and TestsLocomotive

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236.586   Daily or after trip test.

This rule prescribes inspection and test daily or after each trip of the automatic cab signal, train stop, or train control apparatus on each locomotive operating in equipped territory, except where periodic tests are performed on such locomotives at intervals of not more than two months.

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Applies to automatic cab signal, train stop, and train control systems.

This rule requires that the automatic cab signal, train stop, or train control apparatus on each locomotive operating in equipped territory be inspected and tested either once every 24 hours or within 24 hours before departure on each trip.  Daily or after trip inspections and tests are not required for locomotives which are subject to periodic tests at intervals of not more than two months.

The purpose of the test is to determine the device is functioning properly before being dispatched into equipped territory.  The test is required to be made by an employee capable of detecting defective conditions and taking corrective action prior to the locomotive being dispatched from its initial terminal.  In all systems the daily or after trip test shall consist of a general inspection of the apparatus for evidence of damage or wear and a complete cycle of the system’s functions, in addition to the following:

In intermittent inductive automatic train stop system, the test shall determine if the apparatus is properly sensitive, that an automatic application can be forestalled, that an automatic application causes a full service application, that the brakes cannot be released during an automatic application until sufficient time has elapsed to stop a train from maximum authorized speed (reset time), and that seals are properly applied unless device is to be cut out between initial terminal and equipped territory.

In continuous inductive automatic train stop system, the test shall determine that an automatic application can be forestalled, that an automatic application causes a full service brake application, that the brakes cannot be released during an automatic application until sufficient time has elapsed to stop a train from maximum authorized speed (reset time), or the condition that caused the automatic application ceases to exist, and in non-coded continuous inductive automatic train stop system that pick-up of the device is within specified limits, and that seals are properly applied unless device is to be cut out between initial terminal and equipped territory.

In continuous inductive automatic train control system, the test shall determine that overspeed causes an automatic brake application unless suppressed, that an automatic application causes a full service brake application, that the brakes cannot be released during an automatic application until sufficient time has elapsed to stop a train from maximum authorized speed (reset time) or the speed of the train has been slowed to a predetermined rate, or the condition that caused the automatic application ceases to exist, and in non-coded continuous inductive automatic train control system, that pick-up of the device is within specified limits, and that seals are properly applied unless device is to be cut out between initial terminal and equipped territory.

In automatic cab signal system, the test shall determine that cab signal indications correspond to proper codes or track conditions, that the audible indicator has a distinctive sound and can be heard clearly throughout the cab and that the audible indicator sounds continuously until silenced manually each time the cab signal changes to a more restrictive indication.  

Results of the daily or after trip test are required to be recorded by Rule 236.110.

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236.587   Departure test.

This rule requires that the automatic train stop, train control, or cab signal apparatus on each locomotive be tested prior to entering equipped territory to determine if such apparatus is in service and functioning properly.

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§ 236.587   Departure test.

(a) The automatic train stop, train control, or cab signal apparatus on each locomotive, except a locomotive or a multiple‐unit car equipped with mechanical trip stop, shall be tested using one of the following methods:

	(1) Operation over track elements;

	(2) Operation over test circuit;

	(3) Use of portable test equipment; or

	(4) Use of onboard test device.

	(b) The test shall be made on departure of the locomotive from its initial terminal unless that apparatus will be cut out between the initial terminal and the equipped territory.  If the apparatus is cut out between the initial terminal and the equipped territory the test shall be made prior to entering equipped territory.

	(c) If a locomotive makes more than one trip in any 24‐hour period, only one departure test is required in such 24‐hour period.	

	(1) Whoever performs the test shall certify in writing that such test was properly performed.  The certification and the test results shall be posted in the cab of the locomotive and a copy of the certification and test results left at the test location for filing in the office of the supervisory official having jurisdiction.

	(2) If it is impractical to leave a copy of the certification and test results at the location of the test, the test results shall be transmitted to either (i) the dispatcher or (ii) one other designated individual at each location, who shall keep a written record of the test results and the name of the person performing the test.  These records shall be retained for at least 92 days.

Applies to automatic cab signal, train stop, and train control systems, except automatic train stop system of the mechanical trip type.

The rule requires the departure test be made on departure of the locomotive from its initial terminal and before it enters equipped territory.  If the apparatus is cut out between initial terminal and equipped territory, the departure test must be made prior to entering equipped territory.

The purpose of the test is to determine the apparatus is in service and is functioning properly.

The rule permits departure tests to be made over track elements or test circuits permanently installed for that purpose, or with portable test equipment, or with onboard test equipment.  In any case, it must be so arranged that it will produce any of the various track circuit, or restrictive conditions encountered in actual service.

If a locomotive makes more than one trip in a 24-hour period, only one departure test is required in such 24-hour period.

Section 236.587 requires that whoever performs the test shall certify in writing that the test was made and that the certification and results of the tests shall be posted in the cab of the locomotive.  Further, a copy of the certification and results of the tests is required to be left at the test location for filing in the office of the supervisory official having jurisdiction.  If these records are left in some type of repository (e.g. mail box) at the test location, it shall be of a design to provide reasonable protection from the elements (e.g., wind, rain, snow, etc.). Furthermore, all such test records left at outlying test locations must be picked up in a timely manner (e.g., at least once a week) and filed in the locomotive office nearest the test point location(s).  These records are required to be available for inspection and copying during normal business hours.

The rule takes cognizance of locations where it is impractical for a copy of the test to be left at the location being tested, by providing that the results of the tests may be transmitted to either the dispatcher or to one other designated individual at each location.  In either case, the employee who receives the information is required to keep a written record of the results of the tests and the name of the person performing the tests.

The rule does not permit the railroad to use a third party for reporting purposes, should the person designated not be available for reporting of departure tests.  If the designated person is not available, the engineer must report the results of the departure test and the name of the person making such test to the dispatcher, or else leave a written record of such test at the test location.

The records of departure tests must be retained for at least 92 days.  Note that Section 236.110 also requires that a record be made of the departure test.

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236.588   Periodic test.

This rule requires that except as provided in Section 236.586, periodic tests of the automatic train stop, train control, or cab signal apparatus shall be made at least once every 92 days, and on multiple-unit cars as specified by the carrier subject to approval by FRA.

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Applies to automatic cab signal, train stop, and train control systems.

In keeping with Section 236.586, the prescribed 92 day requirement of this rule is not applicable where periodic tests are made on locomotives at intervals of not more than two months.  No other deviation from these requirements is permissible without approval of FRA.

The daily or after trip test prescribed by Section 236.586 is a test to determine the device is in good condition and functioning properly before being dispatched into equipped territory.  The departure test prescribed by Section 236.587 is a test to determine that the device is turned on, in service and functioning as intended before actually departing into equipped territory.  The purpose of the periodic test prescribed by Section 236.588 is to provide a more thorough and in-depth test and inspection of the electrical and pneumatic equipment.

All defective conditions shall be immediately corrected during the periodic test which shall consist of at least the following tests and inspections:

1.	Thorough examination of the electrical portion including measurement of the insulation resistance.

2.	Measurement of the power supply voltage.

3.	Measurement of the pickup value required to restore the device to normal condition.

4.	Measurement of the release value of the device in continuous non-coded systems.

5.	Test of sensitivity of intermittent inductive automatic train stop system.

6.	Measurement of acknowledging time.

7.	Measurement of delay time.

8.	Measurement of reset time in train stop and train control systems.

9.	Measurement of height of receiver of intermittent inductive automatic train stop and continuous inductive systems having onboard 	test equipment, and of tripper of mechanical trip stop system.

10.	Test of audible indicator.

11.	Replacement of relays with dates that expire prior to next scheduled periodic test.

12.	Replacement of pneumatic apparatus with cleaning dates that expire prior to next scheduled periodic test.

13.	Measurement of accuracy of governor in train control systems.

14.	Cycle test of apparatus to determine that it functions as intended.

Section 236.110 requires that the results of periodic tests be recorded on a form provided for that purpose.

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236.589   Relays.

This rule requires that each relay, except master or primary relay of torque type, be removed from service and shopped at least once every six years.  Master or primary relay of torque type depending on spring tension to return contacts to de-energized position shall be removed from service and shopped at least once every two years.

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Applies to automatic cab signal, train stop, and train control systems.

The rule requires that each relay be removed from service as prescribed, subjected to thorough test, and necessary repairs and adjustment made.

The rule prohibits the relay from being returned to service unless its operating characteristics are in accordance with the limits within which such relay is designed to operate.  In order to preclude loss of shelf time, a date tag may be applied showing when the relay was placed in service.  In the absence of a date tag, or where the date is altered or illegible, the shop date of the relay will be used to determine when the relay should be removed from service.

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236.590   Pneumatic apparatus.

This rule requires that automatic train stop, train control, or cab signal pneumatic apparatus be inspected, cleaned, and the results of such inspection recorded as provided by § 229.29(a).

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Applies to automatic train stop, train control, and cab signal systems.  

This rule requires that pneumatic apparatus of the automatic train stop, train control, or cab signal device be inspected and cleaned at least once every 736 days.

The results of such inspection recorded as provided by § 229.29.

When a locomotive with automatic train stop, train control, or cab signal pneumatic apparatus receives out‐of‐use credit pursuant to § 229.33, the automatic train stop, train control, or cab signal apparatus shall be tested in accordance with § 236.588 prior to the locomotive being placed in service.

§ 236.590 Pneumatic apparatus.

Automatic train stop, train control, or cab signal pneumatic apparatus shall be inspected, cleaned, and the results of such inspection recorded as provided by § 229.29(a).  When a locomotive with automatic train stop, train control, or cab signal pneumatic apparatus receives out‐of‐use credit pursuant to § 229.33, the automatic train stop, train control, or cab signal apparatus shall be tested in accordance with § 236.588 prior to the locomotive being placed in service.

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S&TC  FUNDAMENTALS

49 CFR 236

Subpart E

ATS, ACS, & ATC Systems 

The End

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