Annetts key
Established Member
This problem appears to be interference on both datalinks that serve part if the area.
Last night, as I understand it sixteen points were clipped.
With computer based signalling systems, the main computers (the interlocking) are located in the signalling centre. Trackside Functional Modules or TFM) located in lineside cupboards control the signals, points, plus receive information from the track circuits or axle counters. The interlocking uses the datalinks to communicate with the TFMs.
If communication fails, all the relevant signals and points have to be considered as defective.
The system is designed with two datalinks for system redundancy. In an idea world, if one datalink fails, everything continues working using the remaining “good” datalink.
However, in practice, some failure modes affect both datalinks. When this happens, the signaller looses control of hundreds of items of signalling equipment.
There is no work around for this apart from clipping points and talking past red signals. Or introducing long block manual working (where drivers are instructed to pass multiple signals in one instruction).
Unfortunately, when the problem is interference on both datalinks, it is very difficult to track down the cause. A process of elimination has to be done, with the techs visiting every single location cupboard where the datalinks visit.
As the railway reduces the number of staff and resources, should a failure like the above occur, it takes longer to locate the problem and to try to implement manual signalling. For example, it’s not uncommon for the staff on the ground to find that they don’t have enough point clips to secure all the points.
Lack of staff, staff running out of shift time, lack of spares all add to the problems.
Last night, as I understand it sixteen points were clipped.
With computer based signalling systems, the main computers (the interlocking) are located in the signalling centre. Trackside Functional Modules or TFM) located in lineside cupboards control the signals, points, plus receive information from the track circuits or axle counters. The interlocking uses the datalinks to communicate with the TFMs.
If communication fails, all the relevant signals and points have to be considered as defective.
The system is designed with two datalinks for system redundancy. In an idea world, if one datalink fails, everything continues working using the remaining “good” datalink.
However, in practice, some failure modes affect both datalinks. When this happens, the signaller looses control of hundreds of items of signalling equipment.
There is no work around for this apart from clipping points and talking past red signals. Or introducing long block manual working (where drivers are instructed to pass multiple signals in one instruction).
Unfortunately, when the problem is interference on both datalinks, it is very difficult to track down the cause. A process of elimination has to be done, with the techs visiting every single location cupboard where the datalinks visit.
As the railway reduces the number of staff and resources, should a failure like the above occur, it takes longer to locate the problem and to try to implement manual signalling. For example, it’s not uncommon for the staff on the ground to find that they don’t have enough point clips to secure all the points.
Lack of staff, staff running out of shift time, lack of spares all add to the problems.
