Re: Woman dragged along platform by Tyne-Wear Metro train

On Fri, 11 Apr 2008 14:38:32 GMT someone who may be Chris J Dixon
<chris@xxxxxxxxxxxx> wrote this:-

http://www.rgsonline.co.uk/docushare/dsweb/Get/Rail-41178/Rt2473.pdf

B6.3 Requirements for obstacle detection

To minimise the risk and extent of injury, all external passenger
doors shall be designed to prevent obstacles being trapped in the
door.

I don't think that the bit before the comma is compatible with the
"prevent obstacles being trapped", bit. One can't minimise something
and at the same time absolutely prevent it. It would be better to
say that "doors shall be designed to minimise the chances of
obstacles being trapped..."

a) When the door is closing and a bar with a maximum rectangular
cross section of 30 x 60 mm is trapped with its long edge
vertically between the door leading edge and the frame, or
between door leaves either:
i) the closing force shall be automatically reduced, or
ii) the door shall automatically re-open to allow the bar to be
removed, or
iii) the bar shall be capable of removal by exerting a force no
greater than 150 N.

3cm is quite a big obstacle. Straps of bags and the like are rather
thinner.

b) When an obstacle, in the form of a smooth bar, with maximum
dimensions of 10 x 50 mm is trapped with its long edge vertically
between the leading door edge and the frame or between two door
panels, it shall be capable of being withdrawn with a force not
higher than 150 N, measured perpendicular to the door surface.

1cm is also quite a big obstacle.

Note that in neither case does this prevent the obstacle being
trapped, rather it allows it to be pulled out by someone able to
exert that force.

Note also that a rectangular bar is not something that many
passengers carry with them or wear. It is not representative of what
may get trapped in doors.

However, in other postings I didn't say there is definitely
something wrong with the systems and I repeat that. I think that the
question of whether what is reasonably practical has been done
remains a debatable one.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54
.

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