Gordon Callender, Head of Signalling for Parsons Brinckerhoff
on the 19th May 2008
Gordon Callender, Head of Signalling at Parsons Brinckerhoff and one of the leading innovators in signalling, addressed an audience of Young Professionals on May 19th 2008.
Gordon opened his talk with a detailed history of signalling and how it has progressed. Included in this was an explanation of block signalling using levers, which originated in the mid 19th century, and interlocking, a system which ensures there will be no conflicting train movements when different levers are being operated. He was keen to stress that it is the logic of these principles that still underpins the electric signalling of today.
The discussion then moved on to the different types of signalling currently in operation. Chief among these were the Automatic Warning System (AWS) and the Train Protection and Warning System (TPWS), which specifically aims to stop trains that have already passed a signal at danger. Gordon emphasised the crucial distinction that AWS is fail-safe and TPWS is not. This is because AWS can still function without power being supplied, whereas TPWS becomes totally ineffective without such power to energise the equipment installed on the line.
Following on from this, Gordon went on to express his personal frustration at the level of bureaucracy that accompanies some of the more routine changes relating to signalling. He particularly highlighted the variety of risk assessments, which are required for even the most minor of changes which affect signalling, such as simple platform extensions. Gordon clearly felt risk assessments were unnecessary in such instances, as they simply served to delay the work on the changes required. The fact that signalling costs are so much higher in the UK in comparison with the rest of Europe is something which Gordon suggested could be linked to this reason.
A question and answer session followed, after which the young professionals were left to reflect on a most detailed and enlightening account on signalling.
Written by Andrew Jones, IRO Young Professionals Member
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