Anna Noyd-Dryver Wrote in message:
Clank wrote: Anna Noyd-Dryver Wrote in message: Clank wrote: On the other hand... What's wrong with trolley poles? They seem pretty reliable even in inclement weather*. On a tram, where the poles wouldn't even have to deal with the vehicle moving all over the road to overtake etc., I don't see any reason why they should be particularly problematic. More prone to dewirement, particularly as speed increases. Junction'pointwork' more complicated and prone to failure. More maintenancerequired too, I think. Need changing over at every terminus. Anna Noyd-Dryver With all due respect - and I use that in its extremely unusual totally sincere sense - are all those true, or are they just "received wisdom" used to back-justify the UK's resistance to trolleys (and indeed trams)? My post was based on my knowledge and experience of UK heritage tramwayoperations, my knowledge of UK heritage tramway maintenance, and of OLEequipment fitted;

Genuine question - do you think heritage operations are representative of modern equipment? Do you use modern OHLE in fact? (As I say, genuine question - not clear to me if a heritage tramway is all about the rolling stock or if you also try to keep everything else about it "heritage".)

and finally the fact that non-heritage tramways usingtrolleypoles rather than pantographs are a tiny minority if indeed anyexist at all.

Oh, don't get me wrong - I think it's a bonkers idea and I can't see why anyone would bother to install a new tramway that used trolley poles instead of pans. I'm more interested in the thought experiment of whether it not it's actually as "unpossible!" as might have been suggested.

The junction pointwork here is generally lightweight and simple, and even if it wasn't how much trouble would it be; an awful lot (crossovers etc.) can be done entirely passively, so given that a system like Croydon Tramlink would require all of about 3* sets of points how much overhead (no pun intended) do they really add? * Approximately, and I've not looked in detail, but pretty sure the central loop, and all the various sets of track points for the single line sections on the Wimbledon branch could be handled by passive trolley OHL with no points required - so the only places you need actual points in the OHL are Sandilands, Arena & Church Street. Even in the trailing direction, a frog casting in the OLE presents adisruption to smooth passage of the trolley head, and extra complication tothe layout of wiring and supporting wires, compared to having two plainwires which don’t even have to touch. Taking Croydon specifically, with a little imagination you could get awaywithout a facing frog in the OLE leaving any of the termini or the singleline sections, however you’d need them for entering the three double-tracktermini, at each end of the depot (and vastly increased complication withinthe depot), at Church Street, Sandilands, Arena and each end of EastCroydon. Plus, of course, you lose flexibility for any unusual working, wrong linemoves etc, without added operational complication.

How much of this is goldplating, though?

I mean, the depot, for example... Here, tram and trolleybus operations are simple because drivers are not too proud to routinely get out and use a point lever to change the points when necessary, or to manually move the trolley poles if needed. Does a depot really need fully automated switching, or could someone just buy the drivers some gloves?


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