Two improvements have been made to the ground level signalling, aimed at making the railway easier to operate. At the beginning of the season, the 'Castell' interlock switch, which puts outer home signal GL3 to 'danger' when the key is withdrawn, was re-located from the carriage shed to the ground level steaming bay area. This saves the track steward having to walk to the carriage shed to get the key, whenever an engine or stock movement requires the yard point or steaming bay lifting barrier to be unlocked. The interlock is now housed in a lockable box next to the lifting barrier, the key to the box being kept on the track stewards' key ring. As before, signal GL3 will not return to 'green' until the key is replaced in the lock and turned.

The second improvement concerns the operation of the points. Anyone who has been a points operator on a busy day, with three (or sometimes four) trains running on the ground level track, will know how difficult it is to remember which trains are due to come in to the platform, and which trains are still on their first lap and need to be routed through the loop. In response to requests from several drivers, a facility has been added, to allow the driver to select his own route through the station. The old control handset has been replaced by a new one incorporating an extra switch, which enables the system to be worked under 'driver control' or 'station control'.

Roughly halfway between signals GL3 and GL4, a push button has been mounted on the fence that separates the ground level and raised level tracks. The push button is only active when the handset is switched to 'driver control' mode. Pressing the button operates a latching relay, which toggles the selected route between 'station' and 'loop'. Thus, if the selected route is not the one which the driver requires, pressing the button will switch the station entry point to the alternative route, and inner home signal GL4 will change accordingly, all before the train reaches the signal. Once the button has been pressed, an adjustable timer ensures that it cannot be pressed again until a time interval has elapsed, sufficient to allow the train to pass by. This is to forestall any interference by passengers on the train, who might be tempted to press the button just to see what it does!

The push button has no influence on the station exit point, and the control of train departures is still in the hands of a person at the station. However, this function can now be performed by the platform assistant, removing the need for a points operator. If the driver of an approaching train selects 'loop', and the station exit point is set for the platform road, the driver will see a yellow aspect at signal GL4, followed by a red aspect in the loop itself.

Should it be necessary to control both points from the station for any reason (perhaps during a shunting movement), the handset can be switched to 'station control' mode. In this instance, the driver's push button is disabled, and the handset will perform in the time-honoured manner.

Meanwhile, the raised track signalling continues to perform well, and is nearing the end of its third season of operation. We have had a couple of instances of treadle switch blades catching on the insides of the rails, but these were soon re-adjusted and re-greased. Beyond that, the system has been fault-free. In fact, it is true to say that the only real problem has been with some of the drivers, who occasionally miss a red light through inattention. The result is what is known on the big railway as a SPAD.

A SPAD causes a major headache, because it leaves a red aspect that cannot be cleared after the offending train has moved on. The signal that becomes 'stuck on red' is never the one that was passed in error, but the one preceding it. The explanation is that the treadle of a 'red' signal is inactive, and therefore should the signal be passed, it cannot perform its function of restoring the preceding signal. The offending driver is often unaware of the chaos he has caused, and continues blissfully on his way. This is the one drawback of a sequential system, compared to a track circuited system.

The immediate reaction of most track stewards is to carry out a general reset of the system, by pressing the start button on the controller. This, however, can lead to a dangerous situation, as a train can then enter an occupied section under a green signal aspect. We have therefore decided that an individual reset facility is required, enabling a bogus red aspect to be cleared by the track steward (only) without affecting the rest of the system. The circuit for this has been designed, and the signal gang (Tony Vereker and myself) will be busy again at the close of the season.