Xenophon PCDGS
Veteran Member
This subject appears to appear upon numerous threads, so I feel that one master thread should be created to allow all discussions on this particular mode of transport to appear in the same place.
Surprised Boris or TfL haven't suggested such an idea for London perhaps as part of the London Tramlink
I think I read that the vehicles for the tram-train pilot are going to have dual-voltage capability. Is that correct? Also, are they going to be low-floor or high-floor?
If the answers to my questions are "yes" and "low-floor" they sound ideal for my idea of serving the two HOWL stations on the Swansea District Line if a direct link to Gowerton is ever built to allow HOWL trains to avoid Llanelli.
EDIT2: Was rather confused for a moment, thought I'd posted in the wrong thread- they were merged while I was writing this post!
Why cannot the official Tram-train trials in the Sheffield/Rotherham area take place and be evaluated first, without all this unseemly speculation taking place. Do forward planning by all means, but keep the publicity profile given to this at a low level at the current time.
The Tram-Train vehicles have to be designed to work with both types of infrastructure. They must work on the grooved rails within the street tram network and also be able to interact correctly with switch and crossing equipment as well as check rails on the mainline track. The wheel profile design was therefore important, since we had to ensure it could cope with street rails and heavy rail tracks.
One of the key elements of the [Manchester Metrolink] tram wheel design is that the flangeback has a step in it and we've incorporated that into our wheel design.
We carried out design iterations of the wheel profile to optimise the contact conditions; this gives us the best design compromise for successful operation on both Sheffield tram and Network Rail tracks.
Next, we determined the dynamic behaviour of the vehicle and conducted stability analysis to ensure that the design of the new profile doesn't impact on the risk of vehicle instability, known as 'hunting'.
The wheel design work was complicated by the very different rail head shapes of the two systems; the Sheffield Supertram network has a very flat rail head profile, while the worn Network Rail sections typically have a much smaller effective rail head shape. This necessitated compromise in the wheel and tread design, with significant simulation work being carried out to optimise the new wheel profile shape.
This allowed wheel-rail contact stress and wear rates to be minimised on both systems, while also maintaining safety against derailment.
'Hunting', and the resultant track wear pattern, is causing on-going ride quality issues on the Manchester Metrolink Altrincham and Bury lines.We've submitted our design to the Tram-Train project team for scrutiny and in time that will get submitted to the Rail Safety and Standards Board (RSSB) for approval, because it's a non-standard wheel profile, it has to be approved to make sure it is safe to run on Network Rail. Vossloh is also using the profile for optimising its suspension and once the wheel design has been approved by RSSB, the plan is that services will start at the beginning of 2016.
Technically trams could have heavy rail wheel profiles, but then the grooved rail used on street would have to have a wider and deeper groove than normal tram rails. This would be more hazardous to other road users, particularly cyclists.What I don't understand is why tram vehicles could not have been created with the same type of wheels and track as heavy rail. This would mean that train lines could be converted to tram lines easily, or reversed if in the long term it didn't make any sense. It would also mean that trams and trains could use the same track.