Idea for double-deck articulated Tram based on Talgo 22 concept

[bwhughes]

The vertical curve is very poorly illustrated (apologies in advance).


The trams would use trolleybus-type overhead double wires to avoid current return via the rails.

The track would be 'LR55' rails, which are shaped like troughs and are very shallow compared to ordinary tram rails. They could be installed more quickly and without needing to bring streets into turmoil through utility diversions.


It would not matter so much about speed (maximum c.30 mph) because the purpose of this tram would be to provide as much capacity as physically possible in the existing road space, and operate almost exclusively along streets where vertical curves are minimal.

Certainly a means of relieving the London Underground on the surface would be welcome.

I had the London Buses routes 38 and 73 in mind. These operate every 3-5 minutes each from Victoria bus station, whose stands could be adapted to have tram tracks running through.

The routes of 38 and 73 could be swapped in the Holborn/Tottenham Court Road area so that trams using Oxford Street (present 73) would head for Angel via Rosebery Avenue, and those using Shaftesbury Avenue would head for Euston and King's Cross via Tottenham Court Road itself/Gower Street.

At 35 metres in length, they could fit within existing lines of bus stops along Oxford Street.

 

[transmanche]

The trams would use trolleybus-type overhead double wires to avoid current return via the rails.

Just one question: I'm not sure why you'd use trolleybus-type wires if you're going to have rails.

Using trolleybus-type wires without rails gives you the flexibility to steer around obstructions (and with batteries, even to divert the service). The pay-off is that you have more chance of suffering a dewirement.

If you're keeping the rails, then there seems little reason to have all the drawbacks of trolleybus-type wires, without any of the benefits.

 

[edwin_m]

Just one question: I'm not sure why you'd use trolleybus-type wires if you're going to have rails.

Using trolleybus-type wires without rails gives you the flexibility to steer around obstructions (and with batteries, even to divert the service). The pay-off is that you have more chance of suffering a dewirement.

If you're keeping the rails, then there seems little reason to have all the drawbacks of trolleybus-type wires, without any of the benefits.

I agree with this.

I also don't understand how you cope with a vertical curve. Normal tram articulations are designed so at floor level they just rotate and hinge. For a double deck vehicle at least one of the decks will have to expand and contract lengthways as well.

I believe there have been problems with LR55 rail on curves as its shape makes it very difficult to bend horizontally without it twisting. However they do use something very similar in Prague.

Some thinking also needed about stop dwell times, which are usually what determines the maximum frequency of trams. A modern tram with multiple doors can load much more quickly than a bus, but this probably wouldn't be true for a double decker.

 

[WatcherZero]

Im not sure, think I read something about LR55 being trialled in Sheffield but removed after 8 years because it had worn faster than conventional track.

 

[bwhughes]

Just one question: I'm not sure why you'd use trolleybus-type wires if you're going to have rails.

Using trolleybus-type wires without rails gives you the flexibility to steer around obstructions (and with batteries, even to divert the service). The pay-off is that you have more chance of suffering a dewirement.

If you're keeping the rails, then there seems little reason to have all the drawbacks of trolleybus-type wires, without any of the benefits.

Apologies again; I didn't explain it fully. The main reason for trolleybus-type wires is that avoiding current return through the running rails would act as an additional line of defence against electrolytic corrosion of utilities buried under the road surface.

(which is one of the most important reasons I think for the diversion of utilities in the construction of tramways, other than difficulty in reaching them when if tram track had to be taken up)

It would also mean that trolleybuses could operate on the same streets if bus routes from the west along the A402 corridor were not to be terminated before reaching Oxford Street.
--- old post above --- --- new post below ---

Normal tram articulations are designed so at floor level they just rotate and hinge. For a double deck vehicle at least one of the decks will have to expand and contract lengthways as well.

It may be possible to put the hinge at the floor level of the upper deck in order to balance the expanding and contracting on both decks. Admittedly this would necessitate making the tram vehicles higher, but when following the route Piccadilly Circus - Shaftesbury Avenue - Charing Cross Road (direct, when Tottenham Court Rd upgrade finished) - Euston - King's Cross on Google Street View, it appears that even 5 metre-high vehicles might be manageable.

And vertical curves do not appear to be tight in London compared to Birmingham, Nottingham and Sheffield, where a double deck articulated tram would never be able to run.



Instead of the wheel-guiding levers...
(http://railfaneurope.net/pix/es/car/Talgo-200/white-blue/RENFE_Talgo-6_Rodal_1.jpg)




The connection at the Talgo wheelset could consist of a turntable at upper deck floor level inside a centre-section similar to that between Tyne and Wear Metro cars. The wheelset would be on the lower deck, not immediately touching the centre-section:
http://www.thetrams.co.uk/tyneandwear/pictures/002780


The Talgo wheelset would be used instead of the Jacobs bogie used on the Metro car.



Because the tram segments would be 6 metres long or less (not 12 or 13 metres long like Metrolink) it would not have to be as drastic as the T-68 centre section...(!)
http://www.ngaugeforum.co.uk/SMFN/MGalleryItem.php?id=1942

 

[Peter Mugridge]

I wonder if you could get round the deck differential problem on gradients by having two separate gangways, one for each deck, which are each relatively long and floppy like the ones fitted to the S Stock?

You could then use overlapping supporting plates for the floor on the upper deck to give it walking strength while retaining flexibility and at the same time have the hinge mount at the base; guidance rods with limited movement versions of universal joints could be used to keep the upper deck properly in line.

A double deck multi section tram has got to be technically possible somehow - we just have to figure out exactly how...

 

[34D]

I like the idea of doing away with profiled wheels and instead having rubber-tyred ones

 

[RogerB]

How about close-coupling 2 or more buses when demand is high? No tracks, wires or expanding gangways.

 

[starrymarkb]

I wonder if this is the same BWHughes who used to propose PPM as the solution to everything?

 

[34D]

How about close-coupling 2 or more buses when demand is high? No tracks, wires or expanding gangways.

BSI couplers to transmit electrical signals for power, brakes, etc etc? Wow

 

[RogerB]

As each unit would be a complete vehicle in its own right you would only need to transmit control signals, this could be done wirelessly.

If you used hybrid buses then maybe only use one engine and then you'd provide power cables.