Railway block code
Encyclopedia
The railway block code is a system of bell rings used in Great Britain
to communicate between manually operated Signal Boxes
(the system is not used in modern power signal boxes). Each signal box would have a bell circuit to the box on either side of it along the line. The equipment would consist of a plunger or key (rather like a Morse key) which if pressed, rings the bell in the neighbouring box. The neighbouring box would have a key for communicating back, therefore each box has a key which rings the bell in the other box. Where a signal box communicates with more than one other box (in either direction along the line, and possibly along a branch line
too), each bell would have a different tone, so that the signalman
could tell them apart by ear.
Although codes varied from region to region, the following shows a few selected UK Western region
bell codes:
These would be used as follows (assuming a simple exchange between two signal boxes on a plain section of line) between two signal boxes A and B. Assume a train is to pass from the block controlled by A to the block controlled by B. This must be agreed and permitted by the signalman in box B. Here is the sequence of bell codes and associated actions:
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
to communicate between manually operated Signal Boxes
Signal box
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable...
(the system is not used in modern power signal boxes). Each signal box would have a bell circuit to the box on either side of it along the line. The equipment would consist of a plunger or key (rather like a Morse key) which if pressed, rings the bell in the neighbouring box. The neighbouring box would have a key for communicating back, therefore each box has a key which rings the bell in the other box. Where a signal box communicates with more than one other box (in either direction along the line, and possibly along a branch line
Branch line
A branch line is a secondary railway line which branches off a more important through route, usually a main line. A very short branch line may be called a spur line...
too), each bell would have a different tone, so that the signalman
Signalman (rail)
A signalman or signaller is an employee of a railway transport network who operates the points and signals from a signal box in order to control the movement of trains.- History :...
could tell them apart by ear.
Although codes varied from region to region, the following shows a few selected UK Western region
Western Region of British Railways
The Western Region was a region of British Railways from 1948. The region ceased to be an operating unit in its own right in the 1980s and was wound up at the end of 1992...
bell codes:
| Code | Meaning |
|---|---|
| 1 bell | Call attention |
| 2 bells | Train entering section |
| 2 - 3 bells (2 bells, pause, 3 bells) | Is line clear for light engine? |
| 3 - 1 | Is line clear for stopping passenger train? |
| 4 | Is line clear for express passenger train? |
| 2 - 1 | Train arrived |
| 3 - 3 | Blocking back |
| 5 - 2 | Release token Token (railway signalling) In railway signalling, a token is a physical object which a locomotive driver is required to have or see before entering onto a particular section of single track. The token is clearly endorsed with the name of the section it belongs to... |
| 2 - 5 | Token replaced |
| 5 - 5 - 5 | Opening signal box |
| 6 | Obstruction danger |
| 16 | Testing bells and instruments |
These would be used as follows (assuming a simple exchange between two signal boxes on a plain section of line) between two signal boxes A and B. Assume a train is to pass from the block controlled by A to the block controlled by B. This must be agreed and permitted by the signalman in box B. Here is the sequence of bell codes and associated actions:
- Box A sends 1 bell to box B. (Call attention.)
- Box B replies with 1 bell to box A. (Acknowledgement, indicating readiness.)
- Box A sends 4 bells to box B. (Is line clear for express passenger train?)
- Box B sends 4 bells to box A. (Acknowledgement, giving permission for box A to signal the train into the block controlled by B.)
- (Slightly later.) Box A sends 2 bells to box B. (Train entering section.) This is sent as the train passes box A and enters the block controlled by B.
- Box B sends 2 - 1 bells to box A. (Only after confirming that the train has arrived complete and no portion of it remains within the block section between A and B. This could be done by the guard of the train notifying the signalman or by the signalman observing the tail-lamp.)
See also
- Bell codeBell codeBell codes or buzzer codes are a series of bells or buzzers used on passenger trains in Great Britain and India for communication between the driver and guard.All codes, except 3—2—1, must be acknowledged by repeating the code received....
s are used on multiple unit trains for communication between drivers and guards. - Whistle codes are used by railway engines to communicate with signal boxes and other staff.