Backdrop
A painting or scenic photograph on the wall behind the layout.
Ballast
On real railroads, a layer of material – usually crushed rock, cinders, or gravel – on top of the roadbed that holds the ties in position and facilitates drainage. On a model railroad, ballast is simulated by fine gravel spread between the ties and alongside the track.
Benchwork
Supporting framework for a model railroad layout.
Big hook
A wrecking crane.
Block
On a model railroad, a block is an electrically isolated section of track.
Block signal
A signal at the entrance to a block indicating whether the block is occupied by a train.
Bolster
The crosswise member of the frame of a car at the truck (body bolster) or the crosswise piece at the center of a truck (truck bolster).
Booster
In DCC, the booster takes the low-current signal from the command station and “boosts” it to the high-current signal needed by locomotives to operate DC motors, etc., in conformance with NMRA Standards S-91. Also referred to as power stations or power boosters.
Branch line
Secondary line of a railroad.
Bridge
A structure that supports a track passing over a depression in the terrain or a stream.
Bridge pier
An intermediate support used between bridge spans.
Bridge shoe
An iron or steel casting which transfers the weight of a bridge to its supports.
Bumper
A braced, coupler height blocking device that keeps cars from rolling off the end of a track.
Bus, or bus wire
A main wire, or trunk wire, running under a model railroad. Shorter branch wires, such as track power feeders, are connected to it.
