Templot Club Archive 2007-2020                             

topic: 218Prototype pointwork design for dual tramway/railway operation
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posted: 2 Nov 2007 16:32

from:

rodney_hills
 
United Kingdom

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Hello,

Knowing that some folks are into exact-scale modelling, I thought that some might be interested in the following....

There's a post on the closed Yahoo Group: [croydontramlink], commenting on the contents of the recently-published RAIB report into a Midland Metro drailment at Snow Hill:  http://www.raib.gov.uk/publications/investigation_reports/reports_2007/report382007.cfm 

The post is: http://groups.yahoo.com/group/croydontramlink/message/18803 but youll need to join [croyontramlink] to read it in full.

J. Gulliford started it off by writing: recent report from the RAIB highlights the differences between tram and railway switch and crossing parameters and demonstrates the problems in employing contractors' staff with relevant competencies "

Jim Snowdon wrote:"...Further, what it doesn't comment on, but which is known within the tramway industry, are the variations that have occurred in the design of the switches on the different tramways and the failure of some trackwork designers to appreciate the fundamental incompatibilities between some designs of heavy rail switches and tramway wheel profiles. Not only are the switches used on Tramlink not the same profile as those on Midland Metro, but HMRI is actively working with the industry as a whole to set down better standards for the benefit of those, who are often from a heavy rail background, who are designing new tramways."

Dudley Horscroft wrote at length, starting:"

For all its guff about work procedures and the lack of competencies of the various persons concerned, the real reason for the derailment was the bad design of the points.  

 The particular set of points uses heavy rail type switches.  Over it are operated light rail vehicles with tram type wheels.  When all is in perfect order, repeat “PERFECT ORDER” the two, despite the incompatibility of track and wheel, should operate OK.  But Murphy reigns.  And when all was not perfect, the tram derailed.

 Immediate cause

65 The immediate cause of the derailment was the interaction between the wheel and the switch tip, causing the wheel to climb onto the top of the switch rail (paragraph 31).

 This quotation is nowhere examined for a query – Why was there “interaction between the wheel and the switch tip?”

 The problem is not new.  Following is a quotation from an article in “The Railway Gazette?” dated around 1970......

  " etcetera.......

Anyone interested in the whys and wherefores of the different ways that railway and tramway switches are designed (and the differing wheel profiles) is recommended to take a look at the full posting, by joining [croydontramlink] group.

NB - The email I received from the egroup with the new post cited included an inline image (Figure 2c) but there's whitespace at the place it should be in the archived copy at http://groups.yahoo.com/group/croydontramlink/message/18803  -  so I've raised that issue with the group's admins.


Regards,

Rodney Hills

 


posted: 2 Nov 2007 17:33

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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rodney_hills wrote:
NB - The email I received from the egroup with the new post cited included an inline image (Figure 2c) but there's whitespace at the place it should be in the archived copy at http://groups.yahoo.com/group/croydontramlink/message/18803  -  so I've raised that issue with the group's admins.
Hi Rodney,

If a Yahoo group allows image attachments they are distributed with emails but not stored in the message archive. There is nothing the group admin can do about it. The proper course in Yahoo's eyes is for images to be uploaded to the group's Photos or Files sections.

Removing all stored attachments from message archives was their trade-off for the much improved and faster archive search functions which are now available on Yahoo groups.

There's a completely revamped version of Yahoo Groups waiting in the wings, so it could be all-change again shortly.

regards,

Martin.



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