Signal box bell codes

In mechanically-signalled areas, signallers communicate via a series of bell codes with precisely-defined meanings. The signaller at one signal box taps out the appropriate code on a switch, which causes a bell in the next box to ring the same pattern. To make codes distinctive, pauses are inserted between groups, shown in this list by a hyphen (-). For example, a signaller needing to send the message 'train approaching' will tap once, pause briefly, then twice, pause again, then once to give a 1-2-1 bell message. In most cases, the receiving signaller repeats the message back; there are certain circumstances when this is not necessary. Codes evolved across the entire railway system from the earliest days of signalling.

Codes are listed in numerical order of each group. It will be seen that some codes are not unique (e.g. 2-5); the context and rules under which the code is sent will make the meaning clear.

Network Rail codes

This list shows all standard codes used from 2003 (other codes have existed, including special, location-specific codes).

Code	Meaning
1	Call attention
1-1	Answer telephone withdrawn 2007
1-1-6	Police assistance urgently required
1-2	Signaller required on telephone added 2007
1-2-1	Train approaching
1-2-2	Line blockage completed added 2015
1-2-6	Opposite line, or an adjacent line used in the same or opposite direction, to be blocked for the passage of train conveying out-of-gauge load
1-3-1	Is line clear for Class 3 train?
1-4	Is line clear for Class 9 passenger (Class 373 train)? 'or other passenger train if specially authorised' added 2012
1-4-1	Is line clear for Class 9 empty coaching stock (Class 373 train)?
2	Train entering section
2-1	Train out of section, or obstruction removed reference to 'obstruction removed' deleted 2007
2-1-2	Obstruction removed added 2007
2-1-3	Locomotive arrived
2-1-6	Train that carries speed or route restrictions only and which can pass trains signalled 2-6-1 or 2-6-2 on the opposite or an adjacent line replaced 2012
2-1-6	Train with speed or route restrictions only added 2012
2-2	Locomotive assisting in rear of train withdrawn December 2007
2-2-1	Is line clear for Class 5 train?
2-2-2	Block line for protection purposes added 2015
2-2-3	Is line clear for train requiring to stop in section? withdrawn December 2007
2-3	Is line clear for Class 0 locomotive or locomotives?
2-3-3	Working in wrong direction
2-4	Blocking back inside home signal
2-5	Train withdrawn
2-5	Token replaced
2-5-5	Train or vehicles proceeding without authority in the wrong direction
2-5-5	Train or vehicles proceeding without authority
2-6-1	Train that can pass trains signalled 2-6-1 or 2-6-2 on the opposite or adjacent line which will be signalled 2-6-2 or 2-6-3 at some part of its journey replaced 2012
2-6-1	Train which will be signalled 2-6-2 or 2-6-3 for part of its journey added 2012, replaced 2017
2-6-1	Train that can pass trains signalled 2-6-2 or 2-6-3 on an opposite or adjacent line which will be signalled 2-6-2 or 2-6-3 for part of its journey added 2017, replaced 2018
2-6-1	Train that can pass trains signalled 2-6-1 or 2-6-2 on an opposite or adjacent line which will be signalled 2-6-2 or 2-6-3 for part of its journey added 2018, replaced 2018
2-6-1	Train that can pass trains signalled 2-6-1 or 2-6-2 on an opposite or adjacent line but which will be signalled 2-6-2 or 2-6-3 for part of its journey added 2018
2-6-2	Train that cannot be allowed to pass trains signalled 2-6-2 or 2-6-3, on an opposite or adjacent line
2-6-3	Train requiring an opposite or adjacent line to be blocked
2-8	Home signal defective withdrawn 2014
3-1	Is line clear for Class 2 train?
3-1-1	Is line clear for Class 4 train?
3-2	Is line clear for Class 8 train?
3-2-3	Train drawn back clear of section
3-3	Blocking back outside home signal
3-3	Blocking back withdrawn December 2010
3-3-2	Shunting into forward section
3-3-4	Train or vehicles at a stand withdrawn 2009
3-3-5	Line now clear in accordance with regulation 3.4 for train to approach replaced 2012
3-3-5	Line now clear to clearing point added 2012
3-5	Cancelling
3-5	Cancel last description sent withdrawn December 2007
3-5-5	Restricted acceptance
4	Is line clear for Class 1 train?
4-1	Is line clear for Class 7 train?
4-4-4-4	Transference of tokens withdrawn 2007
4-5 or 9	Train passed without tail lamp
4-5-5	Train or vehicles proceeding without authority in the right direction
5	Is line clear for Class 6 train?
5-2	Train clear of section
5-2	Release token
5-3	Train incorrectly described
5-5-5	Opening of signal box
5-5-7	Closing of signal box where section signal is locked by the block
6	Obstruction danger
6	Emergency alarm
6-2	Train an unusually long time in section withdrawn December 2007
7	Stop and examine train
7-5-5	Closing of signal box
8	Shunt withdrawn
8-2	Distant signal defective withdrawn 2014
8-4	AHB level crossing - trains cautioned. Local control being taken (where communication is not available between adjacent signal boxes) withdrawn December 2007
9 or 4-5	Train passed without tail lamp
16	Testing equipment

Southern Railway codes

These codes were in use in 1939. The original document had alterations pasted over obscuring the earlier meanings.

Code	Meaning
1-2	Shunting between signal boxes within station limits in wrong direction: may shunt movement be made on wrong line?
1-2-1	Is line clear for power-worked inspection car or mechanically or power-worked trolley: through?
1-2-2	Is line clear for empty train: branch?
1-3	Is line clear for passenger train or breakdown van train not going to clear the line: branch?
1-3-1	Is line clear for power-worked inspection car or mechanically or power-worked trolley: required to stop in section?
1-4	Is line clear for light engine or light engines coupled together: branch?
1-4-1	Bank engine in rear of train
1-5-5	Shunt train for following train to pass
2	Train entering section: main line
2	Shunting between signal boxes within station limits in right direction: shunt movement entering section
2-1	Train out of section or obstruction removed
2-1	Shunting between signal boxes within station limits in right direction: shunt movement out of section
2-1	Shunting between signal boxes within station limits in right direction: release slot for shunting
2-1	Shunting between signal boxes within station limits in wrong direction: wrong line shunt movement clear of section at box in advance
2-1-3	Engine arrived
2-2	Is line clear for breakdown van train going to clear the line, or light engine going to assist disabled train: main line?
2-2-1	Is line clear for empty train: main line?
2-2-2	Is line clear for trolley requiring to pass through tunnel?
2-2-4	Is line clear for fish, meat, fruit, horse, cattle, milk or perishable train composed of coaching stock: branch?
2-3	Is line clear for goods or through ballast train or engines and brakes: branch?
2-3	Shunting between signal boxes within station limits in wrong direction: wrong line shunt movement clear of section at box in rear
2-4	Blocking back: inside home signal
2-5-5	Vehicles running away on wrong line
3	Shunting between signal boxes within station limits in right direction: replace slot, shunting completed
3-1	Is line clear for passenger train or breakdown van train not going to clear the line: main line?
3-2	Is line clear for goods or through ballast train or engines and brakes: main line?
3-2-3	Train drawn back clear of section
3-3	Blocking back: outside home signal
3-5	Cancelling 'is line clear' or 'train entering section' signal
3-5	Shunting between signal boxes within station limits in right direction: cancelling 'is line clear for shunt movement' or 'shunt movement entering section' signal
3-5-5	Section clear but station or junction blocked
4	Train entering section: branch
4-1	Is line clear for light engine or light engines coupled together: main line?
4-2	Shunting between signal boxes within station limits in right direction: is line clear for shunt movement on down line?
4-2-2	Is line clear for fish, meat, fruit, horse, cattle, milk or perishable train composed of coaching stock: main line?
4-3	Shunting between signal boxes within station limits in right direction: is line clear for shunt movement on up line?
4-4	Is line clear for breakdown van train going to clear the line, or light engine going to assist disabled train: branch?
4-5	Train passed without tail lamp: to box in rear
4-5-5	Vehicles running away on right line
5	Is line clear for ballast train requiring to stop in section or goods train working at intermediate sidings?
5-3	Last train signalled incorrectly described
5-5	Train divided
5-5-5	Opening of signal box
6	Obstruction danger
7	Stop and examine train
7-5-5	Closing of signal box
9	Train passed without tail lamp: to box in advance
16	Testing indicators and bells

Lancashire & Yorkshire Railway codes

These codes were in use in 1919.

Code	Meaning
1	Call attention
1-2	Is line clear for branch goods trains?
1-2-2	Is line clear for ballast train or officers' special requiring to stop in section?
1-3	Is line clear for branch passenger train?
1-3-1	Is line clear for engine and one or two break vans?
1-3-3	Is line clear for "right away" goods train?
1-4	Is line clear for express cattle or express goods train class B?
1-5-5	Shunt train for following train to pass
2	Train entering section
2-1	Train out of section, or obstruction removed
2-1-2	Is line clear for platelayers' trolley requiring to pass through tunnel?
2-2	Bank engine in rear of train
2-2-1	Is line clear for empty coaching stock train?
2-3	Is line clear for light engine?
2-3-1	Engine and one or two break vans in rear of train?
2-4	Blocking back inside home signal
2-5	Shunting completed, tablet replaced
2-5-5	Vehicles running away
3	Is line clear for ordinary goods or mineral train stopping at intermediate stations?
3-1	Is line clear for ordinary passeuger train or breakdown van train not going to clear the line?
3-2	Is line clear for fish, meat, or fruit train composed of goods stock, express cattle or express goods train class A?
3-3	Blocking back outside home signal
3-3-3-3	Attend telephone
3-5	Cancelling "is line clear" or "train entering section" signal
3-5-5	Section clear, but station or junction blocked
4	Is line clear for express passenger train or officers' special?
4-1	Is line clear for through goods, mineral, or ballast train?
4-2-2	Cancelling "bank engine in rear of train" signal
4-3-1	Cancelling "engine and breaks in rear of train" signal
4-4	Is line clear for fire brigade train, breakdown van train going to scene of accident or light engine going to assist disabled train?
4-4-4-4	Transference of tablets by lineman
4-5	Train passed without tail lamp (to box in rear)
5	Is line clear for fish, meat, fruit, horse, cattle, or perishable train; composed of coaching stock?
5-2	Release tablet for shunting
5-3	Last train signalled incorrectly described
5-5	Train divided
5-5-5	Opening of tablet station
5-5-5-5	Testing controlled or slotted signals
6	Obstruction danger
7	Stop and examine train
7-5-5	Closing of tablet station
8-5-5	Time signal
9	Train passed without tail lamp (to box in advance)
9-5-5	Lampman or fog-signalman required
16	Testing block indicators and bells