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Railroad Glossary and Definitions

A B C D E F G H I J K L M N P R S T  W  Y  
  

ANCHOR SPIKE: A plate holding spike.

 
AUXILIARY FASTENINGS: Tie plates, rail anchors, lock washers, and rail braces.
 
BALLAST: Selected granular material placed on the roadbed for the purpose of holding the track in line and surface.

basic rail terminology

CANT: The inward inclination of a rail, effected by the use of inclined surface tie plates, expressed as a rate of inclination, such as 1 in 40.
 
COMPOUND CURVE: A horizontal curve in which the degree of curvature varies in different parts of the curve.
 
COMPROMISE JOINT: A joint for uniting the abutting ends of rails of different cross section (for example an AREA 90 rail to an AREA 115 rail), or of rails of the same section but with different joint drilling patterns.
 
CONTINUOUS WELDED RAIL (CWR): A number of rails welded together in lengths of 400 ft. or longer.
 
DERAIL: A track structure designed to derail rolling stock in case of an emergency (say for example, a cut of cars rolling down an industrial spur to a mainline track would likely derail upon hitting the turnout at the mainline. A derail set ahead of this point would derail the cars before reaching the mainline reducing the risk of damage to mainline equipment and trackage).

super elevated

SUPERELEVATION: The vertical distance of the outer rail above the inner rail (banking on curves).
 
FASTENINGS: Joint bars, bolts, and spikes or alternative hold down devices such as Pandrols or screws.
 
FIELD SIDE - GAUGE SIDE: The field side of a rail is the face pointing away from the track or the outside face. The gauge side is the side of the rail which guides the wheel flange.
 
FROG: A track structure used at the intersection of two running rails to provide support for wheels and passageways for their flanges, thus permitting wheels on either rail to cross over the rails (you'll see this again when we talk about turnouts and crossings).
 
GRADE: The ratio of rise and fall of the grade line to its length (typically measured in percent grade. Say if a track is on a 1.5% grade, it rises 1.5 feet in every 100 feet of track. The maximum typical grade for railroad practice is on the order of 2% or 2 feet of rise in every 100 feet of track.
 
POINT OF SWITCH: The end of the switch rail farthest from the frog. This is where the switch stand or operating mechanism moves the switch points to change switch position.
 
RAIL ANCHOR: A device attached to the base of the rail designed to prevent it moving lengthwise on the ties.
 
REVERSE CURVE: Two adjoining horizontal curves of opposite direction.
 
ROADBED: The part of the roadway upon which the track structure is supported. I will also refer to this as the SUBGRADE of the track though the subgrade is really just the top surface of the roadbed which is below the ballast.
 
ROADWAY: Includes in addition to the roadbed, the slopes of cuts, fill, ditches, access roads and other related works in the right of way.
 
SHOULDER: The portion of roadbed and ballast which is between the end of the ties and the toe of the ballast slope.
 
SIMPLE CURVE: A horizontal curve of uniform degree throughout the curve.
 
SUBBALLAST: A select granular material which is used to separate the roadbed, or subgrade, from the crushed rock ballast.

tangent track

TANGENT:  
          A straight track.
 
VERTICAL CURVE:
          A special type of curve used to connect two different grades in the track.

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Abutment. A substructure composed of stone, concrete, brick or timber supporting the end of a single span or the extreme end of a multispan superstructure and, in general, retaining or supporting the approach embankment placed in contact with it. (See also Retaining Walls, Wing Wall.)

Adzing machine. A portable power-operated machine designed to adz crossties to provide proper bearing for tie plates.

Aggregate. The sand, gravel, broken stone or combinations thereof with which the cementing material is mixed to form a mortar or concrete. The fine material used to produce mortar for stone and brick masonry and for the mortar component of concrete is commonly termed "fine aggregate" while the coarse material used in concrete only is termed "coarse aggregate."

Alignment: The horizontal location of a railroad as described by curves and tangents.
 
Angle bar. A rail joint bar.

Antichecking iron. A piece of flat iron sharpened on one edge driven into the end of a tie to prevent checking and splitting. It is bent to special designs or to the shape of C, S or Z and called C-iron, S-iron and Z-iron. Drive dowels are used by some roads.

Anticreeper. A device attached to the base of a rail and bearing against a crosstie, to keep the rail from moving longitudinally under traffic. Also called Rail Anchor.
Apron. A waterway bed protection consisting of timber, concrete, riprap, paving or other construction placed adjacent to substructure abutments and piers to prevent undermining by scour. Also placed at the ends of pipes and culverts.

Automatic block signaling. See Signal, automatic block.



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Backfill. Material placed adjacent to an abutment, pier, retaining wall or other structure or part of a structure to fill the unoccupied portion of the foundation excavation. Soil, usually granular, placed behind and within the abutment and wing walls.

Backwater. The water of a stream retained at an elevation above its normal level through the controlling effect of a condition existing at a downstream location such as a flood, an ice jam or other obstruction.

Ballast. Selected material placed on the roadbed to support it and to hold track in line and surface. Ballast preferably consists of sized hard particles easily handled in tamping, which distribute the load, drain well and resist plant growth.

Ballast cleaning. The process of separating dirt from the ballast by shaking and depositing stone back onto the track.

Ballast shoulder. The portion of ballast between the end of the tie and the toe of the ballast slope. It distributes the traffic load over a greater width of roadway and helps hold the track in alignment.

Ballast section. The cross section of a track around and under the crossties and between and above the toes of the ballast slopes. This section may include sub ballast.

Ballast, sub. See Sub ballast.

Ballast tamper. A power-operated machine for compacting ballast under crossties.

Ballast tamping. Compacting ballast under crossties to maintain the line and surface of track.

Batter. Deformation of the surface of the railhead usually close to the end of the rail.

Batter Pile. A support pile driven in an inclined position to resist forces which act in other than a vertical direction. When located in a stream, river or other waterway, it sometimes functions as a cutwater in dividing and deflecting floating ice and debris.

Beam. See Bridge Beam.

Bed Rock. (Ledge Rock.) A natural mass formation of rock material either outcropping upon the surface, uncovered in a foundation excavation, or underlying an accumulation of unconsolidated earth material.

Bench Mark. A point of known elevation or point from which several other elevations are established.

Block. A length of track of defined limits, the use of which is governed by block signals or by some other type of signaling.

Block signal. A fixed signal at the entrance to a block, to govern trains and engines entering and using the block.

Block station. A place at which block signals are located and from where they may be operated.

Block system, automatic. A series of consecutive blocks governed by block signals actuated by a train or engine or by certain conditions affecting the use of the block.

Block system, manual. A series of consecutive blocks, governed by block signals.

Bolted rail crossing. A railroad crossing assembled from rolled rail with bolted connections as distinguished from solid cast crossing frogs.

Bond plug. A piece of metal resembling a tapered rivet, used to fasten a bond wire to a rail.

Brace, rail. A device used at switches, movable-point frogs, etc., in combination with switch tie plates, for holding rail in place. Also used on rails at sharp curves to maintain the gage and prevent overturning rail.

Branch, branch line. The route miles of track carrying trains from mainline to destinations on lesser priority trackage than mainline track.

Bridge, ballast deck. A bridge with a solid floor provided with drains and covered with ballast, to provide normal and uniform support for track and conforming generally to standard construction used in the same tracks as constructed on roadbed.

Bridge beam. A portion of the bridge structure receiving and transmitting vertical, transverse, or oblique stresses produced by externally applied loads, when supported at its end or at intermediate points and ends. The beam resists the development of internal bending or flexural stresses. It could be rolled metal I-shaped or H-shaped. An I-shaped piece or member composed of plates and angles or other structural shapes united by bolting, riveting or welding. In general, those types of pieces or members are described as built-up beams. These terms are also applied to and define, in general terms only, variations in shape, size and arrangement of beam type members notable circles; to introduce bend in stock rails; and for a variety of allied operations. Two common types are the Samson and the Jim Crow, the latter sometimes modified by addition of a roller for continuous bending of rails.

Bridge, deck span. A bridge in which the track is carried on top of the stringers (girders) or trusses.

Bridge, girder. A bridge in which the track is supported on the top of (deck girder) or between two or more steel plate girders (trough girder), normally used on spans of 30 to 120 feet.


Bridge, I-beam. A stringer type bridge in which the stringers are steel I-beams that directly support the track or ballast section.
  

Bridge seat. The top surface of an abutment or pier upon which the superstructure span is placed and supported. For an abutment it is the surface forming the support for the superstructure and from which the hackwall rises. For a pier it is the entire top surface.


Bridge, stringer. A deck type bridge in which wooden or steel I-beam stringers carry the track across from one bent or pier to another with or without intermediate support.


Bridge, through span. A bridge in which the track is carried between girder or trusses. Girder and pony truss bridges (trusses without overhead braces) are called half-through spans; truss bridges with overhead bracing are called through spans.


Bridge tie. A sawed tie usually preframed and of the size and length required for track on a bridge. Usually hardwood.


Brush. Woody growth along the right-of-way.


Buckle. To fail by an inelastic change in alignment (usually as a result of compression). To lose line of track by bulging.


Butt Weld. A weld joining two abutting surfaces by depositing weld metal within an intervening space. This weld serves to unite the abutting surfaces of the elements of a member or to join members of their elements abutting upon or against each other. Butt rail welding one rail to another can be accomplished in-plant electrically or by a thermite process in the field.


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Cant. Tilt or inclination, as the inward inclination of a rail, accomplished by using canted tie plates. The undesirable outward tilt of tie plates on sharp curves.

Capillary action. The process by which water is drawn from a wet area to a dry area through the pores of a material.

Car, ballast. A car specially designed for carrying and distributing ballast.

Car, Hand. A four-wheeled, hand operated railroad work car for transporting men and tools.

Car, motor. A motor-driven railroad work or inspection car.

Car, trailer or push. A four-wheeled railroad work car designed to be pushed by hand or pulled by a motor car.

Catenary System. A system of wires suspended between poles and bridges supporting overhead contact wires normally energized with electricity.

Cattle guard. See Stock guard.

Check. A small lengthwise crack or separation of wood fibers, caused by superficial shrinkage of a timber.

Chisel, track. A handled tool to be struck by a sledge, for cutting rail by scoring the base and web until breakage occurs, or for similar cutting. A rail cutter.

CTC-Centralized Traffic Control. The manipulation of automatic and/or cab signals and power operated switches from a central location where signals supersede the superiority of trains.

Circuit, track. A low-voltage flow of electricity in the rails of a track when they are bonded at the joints and form a complete circuit.

Catch basin. A receptacle, commonly box-shaped and fitted with a grilled inlet and a pipe outlet drain designed to collect rain water and debris from the surface and retain the solid material so that it may be removed at intervals. Catch basins are usually installed at the junction where several drain pipes join, beneath a bridge floor, or within the approach roadway with a grilled inlet adjacent to the roadway curb.

Clip, switch. The device by which the switch rod is jointed to the switch rail. It is usually united with the switch rail by bolts or rivets. It sometimes has staggered bolt holes in the horizontal leg for making detailed adjustments in positions of the switch rails.

Clip, transit (switch). A switch-rod clip drilled with several holes in a line diagonal to the axis of the switch rod, for effecting adjustments in the throw of the switch.

Closure rail. The lead rails connecting the heels of a switch with the toe ends of a frog.

Coefficient of Thermal Expansion. The unit strain produced in a material by a change of one degree in temperature.

Compression. An axle force or stress caused by equal and opposite forces pushing at the ends of a member. In simple bending it is also present above or below the neutral axis.

Compromise bars. Special joint bars to connect rails of different section in such a way that the gage sides and the top of the head and running surfaces are held in line. Also called offset bars.

Computer. An electric calculator capable of receiving programmed data and interpreting, manipulating and storing the data. The system is composed of (1) a card reader/punch which functions as an input/output device, (2) a central processing unit (CPU) which is where the actual computing is done, (3) a printer which is an output device, and (4) a disc drive and (5) a plotter which can provide graphic display of program output. Computers vary in size and speed of computation. Data storage varies between disc, tape and drum types.

Contact (Trolley) Wire. The overhead wire, sometimes referred to as trolley wire, which the pantograph of an electric locomotive rides against (contacts) to collect its electrical current (source of power).

Crane, track. (Also called maintenance crane.) A power-operated crane used principally for setting rails in track renewal, but having many similar uses in maintenance work.

Crank, adjustable (switch stand). A switch operating device by which the position of the mechanism at the base of the spindle can be altered to adjust the switch.

Crank, breakable (switch stand). A short crank casting of soft metal, designed to break when the switch is run through and therefore prevent damage to switch-point rails.

Creosote. An oily aromatic compound distilled from tars, used in the preservation of wood exposed to the elements.

Crib. (1) The ballast or the open space between two adjacent crossties, (2) A crisscross structure of logs, timber, concrete or other members, used to retain a fill or as a bridge support.

Cross level. The distance one rail is above or below another. This should not be confused with Superelevation on curves.

Crosstie. See Tie.

Crossing, grade (Xing). A crossing or intersection of a railroad and a highway at the same level or grade.

Crossing protection. An arrangement of signs or electric signaling devices designed to prevent accidents at grade crossings. May include short arm gates.

Crossover. Two turnouts with the track connecting their frogs, arranged to form a passage between two nearby and generally parallel tracks.

Curvature, degree of. A measure of the sharpness of a simple curve in which a 1deg. curve is taken as the central angle subtended by a chord or arc of 100 feet and for which the radius is taken as 5,730 feet. Sharper curves are in direct proportion, i.e., a 10deg. curve is taken as one having a radius of 573 feet. Railroads use the chord definition - highways the arc of definition.

Curve, compound. A curve composed of two or more simple curves which join on common tangent points or common easement curves and which lead in the same general direction, i.e., to left or right, but each with different radii.

Curve, easement. A curve, the degree of which varies in some definitely determined manner to give a gradual transition between a tangent and a simple curve or between two simple curves. Also called spiral easement and transition spiral.

Curve, reverse. A curve composed of two simple curves which join at a common tangent point or by a short tangent track or a reverse easement curve, and bear in opposite directions, i.e., as to left and right or vice versa.

Curve, simple. A curve in the form of an arc of a circle usually described as to its degree of curvature.

Curve, vertical. A curve in the profile of a track to connect intersecting grade lines and to permit safe and smooth operation of trains over summits and across sags.

Curved lead (turnout). The rail from heel of switch to toe of frog.


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Degree of curvature. See Curvature, degree of.

Depth, ballast. The depth from the bottom of tie to top of sub ballast or sub grade. (The ballast between the ties (in the cribs) is a part of the ballast section but its depth is not a part of the specified ballast depth.)

Deenergized-Apparently Dead. Electric apparatus, such as overhead wires, third rail, transformers, switches, motors, etc., is deenergized when disconnected from the normal power source, but such apparatus is dangerous to life until it is known to be properly grounded.

Derail. A track safety device to guide rolling stock off the rails at a selected spot as a means of protection against collisions or other accidents.

Derailment. Anytime the wheels of a car or engine are off the head of the rail.

Dolly, rail or timber. A device consisting of one or more wide rollers mounted in a frame, used as a platform and as a truck for moving rail, long heavy timbers, and other items.

Drill, track. A machine designed to operate horizontally to drill holes through webs of rails, especially for track bolts. It may be a one man ratchet drill or a geared drill machine with a frame, rail clamps, feed screw, high speed steel bit and chuck, and alternating crank handles turned by two men otrack to another.

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Easement curve. See Curve, easement.

Electrified Territory. That portion of the railroad consisting of main tracks, secondary tracks, sidings, yards and industrial tracks equipped for electric train operation by catenary system or by third rail and necessary substations, transmission and signal power lines located above or adjacent to the tracks.

Elevation (of outer rail on curve). See Super elevation.

End post. The piece of an insulating joint which separates the rail ends.

Energized-Live (Dangerous to Life). Electric apparatus, such as overhead wires, third rail, transformers, switches, motors, etc., is energized when connected to the normal power source. All systems are considered to be energized until a qualified individual knows the circuit has been de-energized.

Engine, Booster. Dating from the Superpower steam engine days. The booster was located on the rear axle of the trailing truck (usually) or the fore axle of the forward truck on the tender. Most booster engines were built by the Franklin Steam Engine Co.  Due to  the added weight of the larger grate area on the superpower steamers (after about 1925, the Lima A-1 Berkshire being considered the first of that extended family). this weight and the little steam traction engine driving the axle added 10-15,000 lbs additional tractive effort for starting up heavy freights ( they could run up to about 25 mph).

Engine Burn. Destruction of rail head metal caused by spinning locomotive wheels. Engine Burn Fracture is a rail break caused by an engine burn.

Expansion shim (rail). Spacer inserted between ends of abutting rails while track is being laid to provide allowance for expansion of steel when temperature changes.

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Fastener, tie-plate. A special tie-plate long enough to support the bases of a guard rail and the adjacent running rail and with a rail brace riveted to it for supporting the guard rail.

Fastenings, auxiliary track. Spring washers, tie plates, rail braces, rail anchors and other accessories.

Fastenings, track. A term commonly applied to splice bars, bolts and spikes.

Fill. (Filling). Material, usually earth, used for the purpose of raising or changing the surface contour of an area, or for constructing an embankment.

Fishing space. Space between head and base of a rail occupied by a splice bar (angle bar, joint bar).

Flange. 1. A projecting edge, rib or rim on any object such as the base of a rail on the top and bottom horizontal parts of a beam or girder. 2. On a car wheel, the inside rim which projects below the tread.

Flange frog. See Frog, self-guarded.

Flanger. A form of plow for clearing ice and snow from the inside of rails to provide a clear passage for wheel flanges. Sometimes placed under a special car called a flanger car, but usually carried under a snowplow. Also frequently attached to locomotives, either on or just behind the pony trucks.

Flangeway. Space between running rail and guard rail or timber in road crossing to provide clearance for passage of wheel flanges.

Flare opening. Horizontal distance between the gage line of running rail and the side of the head of a guard rail or frog wing rail at the widest part of its flared end.

Flow of metal (rail). Rolling out of steel on the crown of a rail toward sides of the head. More common on the low side of a curve located where less than established speed is used frequently.

Forms. (Form Work, Lagging, Shuttering). The wooden or metal construction, providing means for receiving, molding and sustaining in position the plastic mass of concrete placed therein to the certain dimensions, outlines and details of surfaces planned for its integral parts.

F.R.A. Federal Railroad Administration. A government agency under the U.S. Department of Transportation.

Fracture, detail. A progressive transverse fracture originating in the head of a rail.

Frog. A device used where two running rails intersect, providing flangeways to permit wheels and wheel flanges on either rail to cross the other.

Frog angle. Angle formed by intersecting gage lines of the rails, or by tangents to the gage lines at their point of intersection when the frog is curved.

Frog number. One-half the cotangent of one-half the frog angle, or the number of units of centerline length in which the spread is one unit. The rate of spread of the gage lines at the frog. The number of units of length for a spread of one unit.

Frog, point of. The actual point of frog, also called the 1/2 inch point of frog, is the point at which the spread between gage lines is one-half inch, which is the standard width of all manufactured frog points except solid manganese steel frogs. In the latter, the metal point is five-eighths inch wide, but the 1/2 inch is marked on the casting. All measurements are made from the 1/2 inch point of frog. The theoretical point of frog, the point of intersection of the gage lines, is at a distance ahead of the 1/2 inch point which in inches is equal to one-half the frog number. This dimension is needed in turnout layouts.

Frog rigid bolted. A frog built entirely of rolled rails, with fillers between rails, and rigidly held together with bolts.

Frog, self-guarded (flanged frog). A frog with a guard member for guiding the flange of a wheel past the point of frog by engaging the tread rim of the wheel in a horizontal plane above the top of the running surface of the frog. This makes a guard rail unnecessary.

Frog, spring. A frog constructed so that one wing rail will spring open when activated by force of the wheel flange passing through it.

Frog, throat of. Point at which the converging wings of a frog are closest together.

Frozen joint. A joint so tight that the rails cannot move as temperature varies.

Fusee. A pyrotechnic signaling device carried by train crews and track workers. When ignited it burns with a red light for a short period of time. A fusee may be dropped from the rear of a train to warn following trains of danger and it is used in many other ways, including emergency use by track workers to indicate to an approaching train a dangerous condition of track or structure. It is used either in daylight or darkness.

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Gage Line. A line five-eighths inch below the running surface of a rail on the side of the head nearest the track center; the line from which measurements of gage are made.

Gage, narrow. A gage narrower than standard gage. A gage of 24 inches or less is commonly employed for industrial railways. Meter gage is often used in foreign countries.

Gage of track. Distance between gage lines of rails laid in track.

Gage rod. A device for holding track to correct gage, generally consisting of 11/4 inch rod with a forged jaw on one end and a malleable jaw on the other end, adjustable through a locknut. Sometimes consists of a rod made in two parts with a solid jaw on each, united by a turnbuckle. Also called a tie rod.

Gage tool. A tool by which the gage of track is determined. It is made of wood and steel, or all steel and sometimes has a guard rail gage attached. It may be combined with a track level.

Gaging (of track). Bringing two opposite rails into their correct relative positions as regards to their distance apart.

Grade. Rate of rise or fall of the grade line, expressed as a percentage of length; feet of rise or fall per 100 feet of length. Also, gradient. A steady rise or fall of one foot per 100 feet is a 1% grade.

Grade crossing. See Crossing, grade.

Grade line (grade). 1. The line of a profile representing top-of-rail elevations of track. 2 A series of staked elevations transferring this line to the ground or roadbed.

Grade separation. A term applied to the use of a bridge structure and its approaches to divide or separate the crossing movement of vehicular, pedestrian or other traffic, by confining portions thereof to different elevations.

Grade rail. The rail first surfaced to track elevation; the line rail on tangents, the inner or low rail on curves.

Guard rail. 1. A rail laid parallel to and inside a running rail to prevent wheels from being derailed or to hold wheels in proper alignment and keep wheels on the other rail from striking the points of switches or frogs in turnouts or crossings. 2. An additional pair of rails laid parallel to and between the running rails of bridges, bridge approaches, and at other critical locations, to keep derailed wheels on the ties and near the running rails.

Guard rail clamp. A device consisting of a yoke and fastening devices engaging the running rail and guard rail. Not all guard rails have clamps.

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Head block (switch). A pair of ties (or, in old types of turnouts, a single tie) used to support the switch-point operating mechanism and the switch stand.

Head rod. The switch rod nearest the point of a switch, usually placed between the two head block ties.

Heater, switch. A device for melting snow at switches by means of steam, an electric current, gas jets, or oil.

Heel block (switch). A block which spans joints and fills the space between adjacent rails at the heel of a switch, joined with outside splice bars by continuous bolts to form a unit joint. Also serves as a foot guard.

Heel length. Disering freight at the house. Distance between the heel end and half-inch point of a frog, measured along gage lines.

Heel of frog. The end of a frog farthest from the switch.

Heel of switch. The end of a switch rail farthest from the point of switch.

Heel spread (frog). Distance between gage lines at the heel end of a frog.

Heel spread (switch). The distance between the gage lines at the heel of the switch rails.

Highway-crossing protection. An arrangement of one or more highway-crossing signals, with or without gates, to protect highway traffic.

House track. Tracks serving freight houses.

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Insulating rail joint. Sometimes called Insulated Joint. A rail joint designed to stop the flow of electric current from rail to rail, as at the end of a track circuit, by means of nonconductors so placed as to separate rail ends and other metal parts.

Insulated switch. A switch in which the fixtures, principally the gage plates and the switch rods connecting one rail to the other, are provided with insulation so that electric currents will not be shunted. Also, the turnout rail contains an insulating joint.

Impedance bond. An electrical apparatus at code change points in electric traction areas to separate signal and traction current.

Interchange track. A track used for the transfer of cars from one railroad to another.

Interlocking. An arrangement of signals, switch lock, and signal appliances so interconnected that their movements succeed each other in a predetermined order. It may be operated manually or automatically.

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Jack, track. A compound ratchet-lever jack which trips its load by a single operation, as distinguished from an automatic lowering jack which lets the load drop by successive stages. There are two kinds: single-acting, in which the load is raised on the down stroke of the lever; and double-acting, in which the load is raised on both up and down strokes. Track jacks now usually have 15 ton capacity.

Joint. The junction of two rails or of like materials in bridge members.

Joint bar. A steel angle bar or other shape used to fasten together the ends of rails in a track. They are used in pairs, and are designed to fit the space between head and flange (fishing space) closely. They are held in place by track bolts. Also, called angle bar, rail joint bar, and splice bar.

Joint-bar drilling. Provision of suitable holes at the ends of rail, switch, frog, or other track member to receive joint-bar bolts. In specifying joint-bar drilling, give the distance from rail end to center of the first hole, successive distance between centers of holes, vertical locations of holes, and their diameter.

Joint, compromise. A special rail joint, sometimes also called a step joint, for uniting rails of different sections; made so it brings gage sides and joined rail heads into line so that continuous smooth surfaces are presented to treads and flanges of passing wheels.

Joints, supported and suspended. A supported rail joint has a tie directly under the rail joint. A suspended joint is one in which ends of the rail joint are carried by two consecutive ties.

Joint tie. A cross tie used under a rail joint.

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Keeper, switch-stand. See Latch, switch-stand.

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Latch, switch-stand. A device for catching and holding the lever of a switch stand in position; also called a switch keeper. Two latches are used at each switch stand.

Lead, actual. The length between the actual point of switch and the half-inch point of frog, measured on the line of the straight track.

Lead, curved. The degree of curvature in a turnout between the heel of the switch and the toe of the frog, measured on the centerline of the turnout track.

Lead track. An extended track connecting either end of a yard with the main track.

Lens, switch lamp. A lens set in a switch lamp. A wide-angle lens, which spreads a light of low intensity over a wide area, is most commonly used with yard switches.

Level. The condition of a track in which the elevation of the rails is transversely equal. Also a tool used to determine that condition in surfacing track.

Line. The condition of track in regard to uniformity in direction over short distances on tangents, or uniformity in variation in direction over short distances on curves.

Line rail. The rail on which alignment is based; the east rail of tangent track running north and south, the north rail of tangent track running east and west, the outer rail on curves, or the outside rails in multiple track territory.

Lining track. Shifting the track laterally to conform to established alignment. Maintenance lining is ordinarily done during repairs; general lining is done to make the track conform throughout to predetermined alignment.

Lipped joint. The junction of two rails when the gage sides are not in alignment.

Live load. A dynamic load such as traffic load that is supplied to a structure suddenly or that is accompanied by vibration, oscillation or other physical condition affecting its intensity.

Lock washer. A spring washer.

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Mainline. Route miles of track systems carrying main tracks.

Main track (M.T.). A track extending through yards and between stations upon which trains are operated by timetable or train order or both, or the use of which is governed by block signals.

Marker, snow flanger. Post or sign indicating the proximity of an obstruction which makes it necessary to raise snow flangers or close snowplow wings.

Mate. A structure somewhat similar to a frog point, placed opposite a tongue switch to guide wheels and carry them throughout the extent of the switch. It is frequently used in industrial tracks laid in paved streets.

Middle ordinate. The distance measured from gage line of rail on a curve to the middle of a string drawn taut and held to contact with gage line of rail at its ends. The middle ordinate forms a convenient means of measuring detailed curvature and is used in the adjustment of curves and the investigation of accidents. It is also a factor in bending rails to a desired curvature.

Movable bridge. A bridge of any type having one or more spans capable of being raised, turned, lifted, or slid from its normal vehicular and/or pedestrian service location to provide for the passage of navigation. The movements of the superstructure may he produced either manually or by engine power

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Nail, dating. A galvanized or copper nail with a large head in which the last two numerals of the year are stamped; used when a tie is laid or treated to indicate its service life.

Number, turnout. The number corresponding to the number of frog used in a turnout.

Nutlock. A spring washer.

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Pantograph. A device located on top of electric engines which collects power from the overhead contact wire by means of a sliding contact shoe.

Parent track. A track from which a turnout is constructed. A main track is the parent track in regard to a passing track or spur, a ladder track is the parent track in regard to the yard tracks.

Passing track. A track auxiliary to the main track used for meeting or passing trains.

Phase break. A location where overhead wires are arranged to provide an insulated section between different sources of electric power.

Pile. A member usually driven or jetted into the ground and deriving its support from the underlying strata, and by the friction of the ground on its surface. The usual functions of a pile are: (a) to carry a superimposed load; (b) to compact the surrounding ground; (c) to form a wall to exclude water and soft material, or to resist the lateral pressure of adjacent ground.

Platform, high. A passenger station platform at approximate car-floor height.

Platform, low. A passenger station platform at approximate top-of-rail height.

Point of switch, theoretical. The point where the gage line of the switch rail, if produced would intersect the gage line of the stock rail. Also called vertex.

Point rails. Switch rails.

Post, bumping. A device at the end of a stub track to prevent rolling stock from going off the ends of the rails.

Pressure grouting. A method of pumping concrete into unstable soil to restore support.

Profile. A longitudinal section through a track that shows elevation and depression. Also, a drawing showing grade line of a railroad, usually obtained from levels taken on top of the rail.

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Rail. A rolled steel shape designed to be laid end-to-end in two parallel lines on ties, to form a track for railroad rolling stock, traveling cranes, and the like.

Rail anchor. A device attached to a rail to keep it from moving longitudinally as a result of temperature change or under traffic. Also called anticreeper.

Rail bender. A tool or shop machine for bending rails to fit curves in tracks, turnouts, or turntable circles; to introduce bend in stock rails; and for a variety of allied operations. Two common types are the Samson and the Jim Crow, the latter sometimes modified by addition of a roller for continuous bending of rails.

Rail bond. A device used to transfer an electric circuit at a rail joint.

Rail brace. A metal casting made to fit against the side of a rail or guard rail and to be spiked to the tie on the outside of a track or the inside of a guard rail to prevent the rail from inclining backward with the thrust of wheels. Made in plain and adjustable types.

Rail brand. An identification mark, including manufacturer's name or initials, month and year the rail was rolled, weight per lineal yard, initials of section, number of the heat, portion of the ingot, and process of manufacture.

Rail creeping. Intermittent longitudinal sliding movement of rails in track under traffic or because of temperature changes. The effect of rail creeping is resisted by anticreepers or rail anchors.

Rail fastenings. See Fastenings, track.

Rail, high. The outer or elevated rail of a curved track.

Rail joint bar. See Joint bar.

Rail joint base plate. A special tie plate used under some types of rail joints.

Rail joint expander. A rail puller/expander operated by hand or by machine which increases or decreases the gap between adjoining rail ends.

Rail joint, insulated. A rail joint which arrests the flow of electric current from rail to rail, as at the end of a track circuit, by means of nonconductors separating rail ends and other metal parts.

Rail joint, pumping. A rail joint usually poorly supported so that mud is created by passage of wheels and pumped up through ballast.

Rail layer. A small crane, manually or power operated, to set new rail in place with the use of few men.

Rail, lead. See Closure rail.

Rail, low. The inner rail of a curve which is maintained at grade while the opposite or outer rail is elevated.

Rail, relayer. Rail with some wear suitable for reuse in track. Relayer rail is divided into main track relayer rails, and yard and side-track relayer rails. It may be cropped then welded or used as shorter length rail.

Rail rest. A support for one or more emergency-repair rails consisting of two or more shelved upright posts or slabs of timber, iron or concrete.

Rail saw, portable. A tool or machine for sawing steel rails, commonly a hacksaw or a circular steel saw, set in a vertical frame.

Rail section. The pattern or dimensional details of rail, such as width of base, height of rail, thickness of web, width and thickness of head, angle of head, and angle of base. Each particular pattern is identified by a brand name or symbol such as ASCE, AREA, ARA, PRR and others in addition to its weight per yard.

Rail, ribbon. Continuous welded rail free of joints or with very few joints in long stretches.

Reamer. A steel tool designed to true or enlarge holes in wood or steel, to facilitate passage of bolts or rivets.

Reflector. A lens device attached to switch stand, showing different colors to indicate position of switch. The colors arise from light reflected from the locomotive headlight.

Relay. An electrical device which contains motors or magnets which, when excited, cause circuits to open and/or close. This, in turn, allows switches to be thrown or signals to display desired indications.

Relayer rail. See "Rail, relayer."

Retaining wall. A wall for sustaining the pressure of earth or filling deposited behind it, used at railroad fills or cuts. See also Wing Wall or Abutment.

Right of Way. Land or water rights used for the railroad roadbed and its structures.

Riprap. Brickbats, stones, blocks or concrete or other protective covering material of like nature deposited upon river and stream beds and banks, lake tidal or other shores to prevent erosion and scour by water flow, wave or other movement.

Roadbed. The finished surface of roadway upon which track and ballast rest.

Roadbed shoulder. The portion of subgrade lying between the ballast-covered portion and the ditch in cuts, and the top of slope on embankments.

Roadway. The part of a railway prepared to receive track. During construction the roadway is often referred to as the grade.

Rod, operating. A rod attached to a switch, derail, or other device, for moving it from one position to another.

Rotary snowplow. A car with a bladed wheel on the front end set at right angles to track and driven by an engine on the car. It cuts the snow and discharges it to one side of track.

Running rail. The rail or surface on which the wheel bears, as distinguished from a wing rail or guard rail.

Runoff (suface). The grade through which the raised portion of a track is connected with the old grade. It generally includes the two rails and is made at a long easy slope for comfort and safety.

Runoff (curve). The profile through which the super elevation of a curve is brought to the level of the tangent, or through which different elevations on a compound curve are connected.

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Scale, track. A scale with a weighbridge supporting a section of running track, used to find weight of rolling stock.

Scrap rail. Rails of standard section not fit for use as relayer rail.

Screw spike. A cylindrical threaded steel spike with a special head, designed to be turned with a special wrench into holes bored in ties, to secure rails or to act as a tie plate holder in tie plates with holes intended for this use.

Section tool house. A small building used for storing the section motor car or hand car, maintenance-of-way tools, and other equipment of a section gang.

Separator, adjustable. A metal block of two or more parts, acting as a filler between running rail and guard rail and providing a means of maintaining the proper width of flangeway.

Shake (timber). A lengthwise separation of wood, following annular rings.

Sheave. A wheel having a groove or grooves in its face surface for the passage of cable. This term may be applied collectively to include both sheave and its housing block.

Shim, track. A bearing piece, usually wood or metal of various thickness, at least equal to the width and length of the tie plate, for temporary use between the tie plate and ties to raise (surface) the rail to a desired relative elevation. Usually, used to spot surface a track when the roadbed is frozen and the ties cannot be surfaced tamped; or for temporary use to bring the tops of adjoining rails of different height to a desired plane or elevation.

Shoulder, ballast. See Ballast, shoulder.

Side planning. Cuts made on sides of the head of the switch rail to form a taper from the full width of head to the point.

Signal, highway, electric. A highway crossing signal which is actuated automatically by the approach of a train and which then displays one or any combination of several features such as red lights (flashing or nonflashing) horizontally swinging disk, crossing gates, or warning bell, all designed to warn motorists of the approach of a train.

Side track (S.T.). A track used to temporarily store cars.
Siding. A track auxiliary to a main or secondary track for the meeting or passing of trains.

Signaling, automatic block. A system of signals of fixed location, each located at the entrance to a block, to govern trains and engines entering and using that block. Such signals govern movements over a series of consecutive blocks and are actuated by a train or engine or by other conditions affecting the use of the block, such as a broken rail, switch not properly lined, car standing on a turnout foul of a main track or other track obstruction.

Skeletonized track. Track with ballast removed from the cribs between ties.

Slide fence. A warning device connected to signals which warn trains of rock or landslides when fence wire is broken by rock fall.

Snow fence. A structure erected to form artificial eddies on the windward side of a cut far enough to cause snow to deposit between fence and cut. A portable or permanent wood fence, a hedge, or stone fence is usually employed.

Snow melter. A contrivance designed to prevent accumulation of snow and ice in tracks; sometimes a blowtorch held close to the snow, or a steam, electric, oil, or gas heater attached to the rails through the switch leads at interlockings or railroad crossings; sometimes chemical poured or strewn along the tracks.

Snowshed. A roofed structure built over tracks to protect traffic against snow blockades. Restricted to locations where snow encroaches seriously and cannot be handled with plows, usually in side-hill cuts on mountain slopes where snowslides amounting to avalanches frequently bury the tracks.

Spike puller. A steel bar about 5 feet long with a claw end shaped for pulling spikes by leverage; also called a claw bar.

Spike puller extension. A tool with a claw end and two or three pairs of knobs on a straight bar. A spike puller is engaged with the knobs after the claw is slipped under the spike head. It is used to withdraw spikes from flangeways and other places in which a spike puller alone cannot operate.

Spiked switch. A switch with its points held in fixed position by a spike, usually to prevent a disconnected or damaged switch from being thrown through error, or to prevent trains from using a track that has been taken out of service.

Spiral easement. See Curve, easement.

Splice bar. A joint bar.

Split switch. A device consisting of two tapered rails with necessary connections, designed to divert rolling stock from one f reinforced concrete structures.Spotboard. A sighting board placed above and across a track at an established height above top of rail elevation, to indicate a new surface and insure uniformity of surface.

Spring frog. See Frog, spring.

Spring washer. A washer designed to prevent a nut from loosening under vibration. Spring washers are of two types: helical and elliptical. Also called lock washer and nutlock.

Stock guard. A rail-high panel of material difficult for hoofed animals to traverse, used to continue a stock fence across a railroad.

Stock rail. A running rail against which a switch point operates.

Stock rail bend. The bend or set which must be given the stock rail at the vertex of a switch to allow it to follow the gage line on the turnout. Usually, only one stock rail of a switch is bent. The opposite one is straight.

Stop, car. A device for stopping a car by engaging the wheels, as distinguished from a bumper, which engages the coupler of a car or the front bumper beam of a locomotive.

Strain. The distortion of a body produced by the application of one or more external forces and measured in units of length. In common usage, this is the proportional relation of the amount of distortion divided by the original length.

Stress. The resistance of a body to distortion when in a solid or plastic state and when acting in an unconfined condition. Stress is produced by the strain (distortion) and holds in equilibrium the external forces causing the distortion. It is measured in pounds or tons. Within the elastic limit the strain in a member of a structure is proportional to the stress in that member.

Stringlining. A method for determining the corrections to be made in the alignment of a curve, by measuring ordinates to the outer rail and without the use of surveying instruments.

Subgrade. Gravel, crushed rock or the like, usually inferior to the ballast used in the track, spread on the surface of the cut or fill prior to distributing ties and ballast. That portion of ballast over 18" inches below bottom of ties is usually classified as subballast, commonly known as subgrade material.

Subballast. Any material of superior character, which can be spread on the finished subgrade of the roadbed, to provide better drainage, prevent upheaval by frost and better distribute the load over the roadbed.

Substation. A location where power is received at high voltage and changed to required voltages and characteristics for distribution to the catenary system, third rail, and other electric apparatus. It may contain transformers, rotating machinery, circuit breakers, sectionalizing switches, rectifiers, etc.

Superelevation. The height the outer rail is raised above the inner or grade rail, on curves, to resist the centrifugal force of moving trains. This should not be confused with cross level, on tangent (straight) track.

Surface (of track). The condition of a track as to vertical evenness or smoothness over short distances.

Surface, running (tread). The top surface of the railhead on which the wheel tread rides or runs.

Surfacing, out-of-face. Raising the entire track to a new grade.

Switch. A pair of movable track rails, with their fastenings and operating rods, providing a connection over which to move rolling stock from one track to another. Also called split switch.

Switch fixtures. The connecting and bearing parts for the rails of a split switch.

Switch guard. A structure, usually of manganese steel, secured outside the running rail at the point of switch, with suitable flares to engage with the tread rim of wheels and guide them past the switch point without blow or undue wear.

Switch heater. A device for melting snow with heat generated by an electric current, or by gas or oil; used for movable parts of switches, etc.

Switch lock. A fastener, usually a spring padlock, used to secure the switch or derail stand in place and thus maintain correct position of these members.

Switch plate. A special metal tie plate for use on switch ties, each plate being long enough to extend not only under the stock rail and its supporting braces, but also under the switch rail in open position. Switch plates are furnished in sets to correspond with switch length. There are two plates to each tie; however, at point of switch, the two may be replaced by a gage plate which carries both switch rails.

Switch, actual point of. See Point of Switch.

Switch, theoretical point of. See Point of Switch.

Switch-point lug. The lug attached to a switch point, to which the front rod is connected.

Switch rail (point rail). The tapered rail of a split switch.

Switch rod, adjustable. A switch rod with an attachment for altering its length to keep the switch rails in their proper positions. Adjustment is usually effected through staggering holes in the clips which connect switch rod and switch rail.

Switch, staggered-point. A switch in which one point is placed in advance of the other, as in a turnout from inside a curve.

Switch stand. A device by which a switch is thrown, locked, and its position indicated. It consists essentially of a base, spindle, lever, and connecting rod, together with target, and can be equipped with a lamp or banner. Unless described as "low" or "center throw", its target spindle extends 2 feet or more above top-of-rail elevation.

Switch stand, center throw. A switch stand with a spindle higher than 1 foot but less than 2 feet. This type is commonly used in yards, less frequently on main track because targets are not as readily visible to engineman as are high switch stands.

Switch target. A visual day signal fixed on the spindle of a switch stand, or the circular flaring collar fitted around the switch-lamp lens, and painted a distinctive color to indicate the position of the switch.

Switch, throw of. The distance, measured along the center line of the rod nearest the point connecting the two switch rails, through which switch points are moved sidewise to bring either point against the stock rail; standardized at 43/4 inches.

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Tamper, air. An air-driven tool for compacting ballast under ties. Commonly used in sets of 4, 8, or 12 tools in connection with a portable air compressor.

Tamper, electric. An electrically driven tool used for compacting ballast under ties. Commonly used in sets of 4, 8, or 12 tools in connection with a portable generator set. (Electric tampers are of three general classes: vibratory, magnetic impulse, and mechanical impulse.)

Tamper, mechanical. A power-driven machine for compacting ballast under ties.

Team track. A track on which freight is transferred directly between railroad cars and highway vehicles.

Thimble. The cylindrical pieces of an insulating joint which surround portions of the bolts.

Third rail. An electric conductor located alongside the running rail from which power is collected by means of a sliding contact shoe attached to the truck of electric equipment.

Throat of frog. The point at which the converging wings of a frog are closest together just ahead of frog point.

Throw of switch. See Switch, throw of.

Throw rod. The rod attached to the head rod of a switch, connecting the switch to a switch stand or other operating device.

Tension. An axial force or stress caused by equal and opposite forces pulling at the ends of the members. In simple bending it is also present above or below the neutral axis.

Tie. A transverse support to which rails are fastened to keep them in line, gage and grade. Usually wooden or concrete.

Tie plate. A metal plate at least 6 inches wide and long enough to provide a safe bearing area on the tie, with a shoulder to restrain outward movement of the rail.

Tie, plate, canted. A tie plate tapered in thickness usually on a slope of 1 in 20, for the purpose of inclining the rail toward the center of track for easier maintenance of gage, more uniform wear of head, and central loading of rail.

Tie plate, twin. A tie plate in two parts which mate to form a combined width equal to that of the stand tie plate, for use back of the heel of switch to the point where standard tie plates may be applied without their ends infringing.

Tie plug. A wooden pin driven in to fill an unused spike hole in a tie, to exclude moisture, prevent decay, and provide solid wood for redriving the spike. Usually supplied in the form of sticks containing several plugs; frequently of treated wood.

Tie rod. See Gage rod.

Tie spacing. The distances between tie centers in track or turnout.

Tie tamper. See Ballast tamper.

Tie tongs. A tool designed to engage a tie with a lever grip; with handles by which ties can be carried or drawn into or out of the track renewals.

Toe end of frog. The end of a frog nearest the switch.

Toe spread. The distance between gage lines at the toe end of the frog.

Tolerance. An allowance made for a small variation from dimensions specified.

Track, body. Each of the parallel tracks of a yard, on which cars are switched or stored.

Track. The rail, ties, rail fastenings, hardware and roadbed between points four feet outside of each rail.

Track brace. An auxiliary fastening designed to function as a rail brace and a gage rod.

Track fastenings. The term commonly applied to rail joints, bolts and spikes.

Track fastenings, auxiliary. The term commonly applied to spring washers, tie plates, rail braces, anticreepers and gage rods.

Track, house. A track alongside of or entering a freight house; used for cars receiving or delivr operated by electric, gasoline or air power.

Track, ladder. A track connecting successively the body tracks of a yard.

Track-laying machine. A machine designed to minimize the manual labor of placing rails, fastenings, ties and other materials.

Track level. A board with a spirit level attached, to level the rails of a track usually equipped with a series of steps to set superelevation on the outside rail of curves.

Track liner. A device designed to minimize manual labor in lining track. It consists generally of a base resting securely on the roadbed to act as a fulcrum for some form of lever arm.

Track, repair or rip. One of the body tracks in a car repair yard or shed, on which repairs are made to rolling stock.

Track shim. A hardwood or fiber plate, generally as wide as the bearing of a standard tie plate but of a varying thickness; used to restore the running surface of track heaved by frost or otherwise distorted.

Track, storage. One of the body tracks in a storage yard, or a track used for storage purposes.

Track, spur. A track connected with the parent track at one end only.

Trailing point. A switch in which points face away from the normal direction of traffic. A trailing point move would pass over the frog and then the switch points.

Transformer. Apparatus which serves to increase or decrease voltage.

Transpose rail. Changing rail from one side to the other on curves because of headwear from tangent to full curvature or just reversed.

Transition spiral. An easement curve.

Trestle. A bridge structure consisting of beam, girder or truss spans supported upon bents. The bents may be of the piled or of the frame type. When of framed timbers, metal or reinforced concrete they may involve two or more tiers in their construction. Trestle structures are designated as "wooden", "frame", or "framed", "metal", "concrete", "wooden pile", "concrete pile", etc., depending upon or corresponding to the material and characteristics of their principal members.

Train. A locomotive with or without cars and displaying markers.

Truss. A jointed structure having an open built web construction so arranged that the frame is divided into a series of triangular figures with its component straight members primarily stressed axially only. The triangle is the truss element and each type of truss used in bridge construction is an assemblage of triangles. The connecting pins are assumed to be frictionless.

Turnout (T.O.). An arrangement of a switch and a frog with closure rails, by which rolling stock can be diverted from one track to another.


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Wide Flange Beam (Carnegie Beam). A steel rolled member having an H-shape with its flanges wider and its web thinner than an I-beam.

Wing Wall. An extension wall of an abutment wall which retains adjacent earth and/or deflects or guides a stream into pipes, culverts, and the waterway of a bridge.


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Yard Track (Y.T.). A track within a yard used to receive cars for classification for rerouting.

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