The answer about how often is bi-di used is probably ‘not nearly enough’. ETCS is essentially ‘speed signalling’, moving UK rail away from route signalling with a bit of speed control added where necessary. Just think how much interlocking design could be simplified with all the speed control incorporated in the ETCS block processor data.How often are bi-di capabilities we already have actually used? They're good in places but we don't need a national programme of making our railways far more expensive to run. The SWML if done today would probably be bi-di on the centre lines, similar to the Trent Valley, but we don't need every twin track in the country to have the option, even if other countries (mainly ones which use speed signalling) do.
Used creatively bi-di could be used for example to get past failed trains or around possessions with enforced Temporary Speed Restrictions of say 15km/h past work sites. How are train speeds managed past the Hook slip, TSR boards and temporary fencing? A bit crude compared to what ETCS will provide.
The operators need to be asked if bi-di would have helped over a range of incidents over the last twelve months to understand the value (which with the current penalty regime used in the UK will be measured in pounds) of such a change.
BTW why would bi-di be more expensive to run? Once new track layouts have been established and ETCS up and running, apart from extra maintenance if more points are required, (which could be done with trains routed around them more easily than today), where would the extra on going costs arise?
I understand that that UK rail is very risk adverse. I would question if it’s easier to be risk adverse vs. fully quantifying the cost/benefits of mitigating risks.
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Why would bi-di cost a lot more? Yes it will with signals, but marker boards are cheap in comparison. Additional train detection might be required, there is a need to think creatively on signalling layouts, ignoring some traditional concepts, even the need for overlaps might be questioned.Bi di costs a lot more, and in most cases provides limited benefit. The Sums just don’t add up for most locations.
and often extra train detection, plus of course the data / design
As I said previously data generation should be automated. A colleague at Westinghouse in Chippenham was producing Control Tables and SSI data automatically from the track layout some 15 to 20 years ago, AFAIK this was used routinely on a number of Contracts. Extracting data from a CAD drawing isn’t rocket science, it’s something I was doing over 40 years ago.
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