Senin, 22 April 2013

Re: [CanPassRail] PTC was Perceived Risk on Various Modes



The references in the previous post were to a draft regulation, which has not yet been put into force. Here is a link to the current regulation:,_c._1183/page-2.html#docCont

The pertinent part:

12. (1) Signals shall operate for not less than 20 seconds before the crossing is entered by a train at a speed in excess of 10 m.p.h.; provided that where the distance as measured parallel to the centre line of the highway between the governing signal and clearance on the opposite side of the farthest protected track on which trains operate in excess of 10 m.p.h. is more than 35 feet, the operation time of 20 seconds shall be increased one second for each additional 10 feet or fraction thereof; signals shall continue to operate until the train has cleared the crossing.

That is where the 20 second requirement is defined. As noted by other posts, railways typically add 10 percent margin to the minimum, so it often becomes 22 seconds in actual application.

As I understand it, the railways may be voluntarily designing new crossing protection based on the draft regulation, but I believe it is also supposed to be phased in, so existing crossings won't have to be changed immediately.


--- In, Knut <knut@...> wrote:
> Thanks for posting those details.
> I'm glad to see that all this is spelled out in detail and specifically covers the long commercial vehicles in use today.
> But somehow perhaps I misunderstood the 20 seconds (or 22 seconds) that have consistently been quoted.
> I thought that was the minimum time between the activation of the warning signals and the actual arrival of the train.
> If I add up the times in the post below I get as a "normal" minimum interval:
> 7 seconds from the start of the warning signal to the onset of lowering the gates
> 15 seconds worst case to lower the gates to the final position
> 5 seconds after that the earliest time a train should arrive
> …which adds up to a total time of 27 seconds, not 20 or 22.
> That just happens to be the same number as was posted previously for the UK.
> Does the 20 second interval only apply for crossings without gates?
> Seems a bit confusing.
> Knut

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