O
O.R.C.	Conductor. (See Big O)
O.S.	1) On Schedule. 2) To report the passing of a train.
Observation Car	Passenger carrying vehicle, usually at rear of train, with windows and seating arranged to give maximum view of passing scenery.
Occupied Camp Car Signal	A white circular sign with black letters, which must be supplemented by a white light at night. When displayed, it signifies that employees are in, around, or in the vicinity of camp cars.
Oilcan	Tank car
Offsider	[AU] See Second Person
Old Girl	Affectionate term for steam engine.
Old Hand	Experienced railroader usually with high seniority. Also called old head.
Old Man	Superintendent or general manager.
Ole Hoss	Salvage warehouse, or freight on hand.
On The Advertised	According to schedule; right on time. Often called on the card (timecard) and sometimes on the cat hop.
On The Carpet	Commoner version of dancing on the carpet.
On The Ground	Used to describe a derailment.
On The Spot	See Spot.  (See Spot run. Run, Spot, run. Sorry, I couldn't help it.)
Op	Telegraph operator.
Open Air Navigator	Hobo riding freight on top.
Open The Gate	Switch a train onto or off a siding. Close the gate means to close the switch after the train has passed it.
Operation Lifesaver	Nationwide railroad public safety outreach program.
Operator	(Opr) The person in control of a designated section of track who is accountable to the Dispatcher for movement of trains.
Operating Employees	Railroad employees who run trains, such as conductors and engineers.
Operating Rod	The bar connected to a manually operated switch stand or mechanically powered switch machine that moves the points of a switch.
ORC	Old Reliable Conductors, The union that represented conductors during the mid to late 19th century.
Order Board	See Board.
Originating Line Haul Road	The railroad on which any freight shipment starts.
Originating Station	The first station on each subdivision from which a train is authorized to occupy the main track.
OTM	Other Track Material.  Materials other than ties and rails ... spikes, bolts, tie plates, rail anchors, beer, etc.
Out	When a trainman is at a point other than his home terminal, either on or off duty, he is out.
Outlawed	See dogcatchers.
Over The Knoll	Getting up the hill.
Overhead	Electric wire strung above the track which supplies power to electric locomotives.
Overhead Bridge	Any bridge whether railroad, automotive, or pedestrian, which crosses above the trackage.
Overhead Line Haul Road	Any railroad or railroads between the originating line haul road and the terminating line haul road. Also known as a bridge line haul road.
Overhead Route	(Also called Bridge route or bridge traffic.) Freight which is delivered by one railroad to a second railroad for delivery to a third railroad.
Overlap	Where two block signals control the same stretch of track.
Overlap Sign	A sign marking the limit of control of a block signal.