A disaster at such an intermediate location occurred on the Somerset & Dorset Joint Railway at Foxcote, near Radstock, in the Foxcote collision of 1876. This occurred before the S&DJR was equipped for token working and was relying on block instruments only - a catalogue of errors led to two passenger trains entering the same section from opposite ends. In double line working, at times when traffic is light it is convenient to "switch out" an intermediate signal box, allowing the signal boxes on either side to communicate directly for train control. On single lines this is more complicated because of the train tokens being identified with single line sections, but the difficulty can be overcome by some form of long section working. A simple system used separable train staffs which fit together when intermediate block posts are closed, so that a driver receives the train staff for two or more consecutive sections from the first signalman. An alternative system employs special long-section token systems; when long section working is to be instituted, all the short section tokens must be in their respective instruments; by switching to the long-section method, tokens for the long section can then be obtained in the ordinary way. Obviously all the long-section tokens must be restored before the normal working can be resumed. Token instruments can be arranged for unattended operation, when they are operated by the train crew at intermediate crossing loops or at the terminus of the line. This system is widely found in Australia, where traffic density on many lines is low. In the UK it is known as the "No-signalman key token system". Examples on the UK national network are the North Devon Line, where the system was brought into use on 1 December 1987, the Heart of Wales Line (commissioned in 1986), the Matlock branch in Derbyshire and the Liskeard to Looe line in Cornwall. On the latter, the train guard not only operates the Tyer's No.9 electric token instrument controlling the upper section of the branch, but operates the points as well. The lower section is operated on the "One Engine in Steam" principle with a simple wooden staff. Possession of the staff is required to unlock the ground frame controlling the points at Coombe Junction, where the two sections meet. There is no other signalling on the branch except to control entry and exit to and from the main line. After early experience with token systems, it became customary for the starting signal at token stations to be interlinked with the token instrument; on withdrawal of a token, the starting signal lever was released for one pull.