On Sunday, 1 September 2013 01:24:05 UTC-7, kenw wrote:
Spud



If you would prefer to travel on a deep-level underground railway with

untested control systems, that's up to you.



But I suspect most Londoners want the Underground to be safe. And that

means testing new systems thoroughly.



Do you think some signal sengineers simply obtained a full weekend

possession without a proper examination of the needs / alternatives /

impacts?



Think for a moment of the thousands complex actions and interactions

involved in running any kind of high-density railway. The system and

its controllers / users have to "understand"



- state (moving or stationary), location and speed of every train



- route and destination



- location of every signal, junction and station



… and dozens more about which the brethren here will be able to inform us.



Then each of those factors has to be tested both in combination and

with any / every other.



What's the alternative? Trying to squeeze it in to overnight posssions

lasting 4-5 hours, when other routine maintenance is already under way

– for which the power has to be turned off? Assuming that an overnight

posession allows, say, 3.5 hours work, the weekend equates to abut 15

overnights. That's three weeks in which little or no track work or

other maintenance can be done.



And for which, assuming the tests require a number of moving trains,

drivers will have to be taken off their normal duties and rostered for

special "out of hours" shifts (thus reducing their availability during

normal days, which would mean fewer trains when you might want one).



I think if LU inflicted that on us we would indeed be tempted to

describe them in the terms used.


Well said. Hear, Hear.