British shunt signal disc

A white disc crossed by a red bar.

Also known as: Ground disc signal, Dod signal, Shunt disc

Engineering & technicalRoad & transportStandard profile

Meanings

A British ground signal authorising a shunting movement, showing a bar across a disc when on and clear when off.

Officially standardisedVerified fact
Authorises a shunting movement rather than a train movement, and applies only to the line it is provided for.
Contexts: Public information
Officially standardisedVerified fact
Is mounted near the ground because it governs slow movements over short distances, where sighting from a height is unnecessary.
Contexts: Public information

A low circular disc mounted near the ground with a straight bar across its face, rotating clear of horizontal when the movement is authorised.

IdentityHigh confidence: High confidence because the identity is defined by a current official standard.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references.

GERT8000 Rule Book, Signals, handsignals, indicators and signs
Rail Safety and Standards Board (RSSB), Great Britain · retrieved 2026-08-24
The British national rule book module covering signals, indicators and lineside signs. Cited for a signal's identity and its defined meaning on the Great Britain network. Records are descriptive; the Rule Book itself is the operating authority and is not reproduced here.
Railway signalling
Wikipedia · retrieved 2026-08-23
Tertiary reference, cited for the conventional form of a marking or signal and where it is used. Where a national authority or standards body defines it, that source is cited alongside and governs.

Last reviewed 2026-08-25

Meanings

A British ground signal authorising a shunting movement, showing a bar across a disc when on and clear when off.

Officially standardisedVerified fact

Authorises a shunting movement rather than a train movement, and applies only to the line it is provided for.

Officially standardisedVerified fact

Is mounted near the ground because it governs slow movements over short distances, where sighting from a height is unnecessary.

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references.

Sources

GERT8000 Rule Book, Signals, handsignals, indicators and signs
Rail Safety and Standards Board (RSSB), Great Britain · retrieved 2026-08-24
The British national rule book module covering signals, indicators and lineside signs. Cited for a signal's identity and its defined meaning on the Great Britain network. Records are descriptive; the Rule Book itself is the operating authority and is not reproduced here.
Railway signalling
Wikipedia · retrieved 2026-08-23
Tertiary reference, cited for the conventional form of a marking or signal and where it is used. Where a national authority or standards body defines it, that source is cited alongside and governs.

Last reviewed 2026-08-25