• Curves, Grades and LFLRVs

  • General discussion of passenger rail systems not otherwise covered in the specific forums in this category, including high speed rail.
General discussion of passenger rail systems not otherwise covered in the specific forums in this category, including high speed rail.

Moderators: mtuandrew, gprimr1

  by Myrtone
gardendance wrote:I don't know the dimensions, so I can't say that Philly actually has curves as tight as 10m as you say. If they do, I assume they're in critical places from the time they were built, and easing those curves nowadays costs too much.
That's what I read, and it's not surprising given all the right-angle curves at intersections.
gardendance wrote:I'm sure if there was some other remedial curve or tunnel work Philly could have done in the 1980's to handle cars with clearance issues, such as what today's low floor cars seem to have, they would have done so.
Clearance is not the problem, the problem is the lateral bearing forces, since entire carbody sections are tracking curves. Entire carbody sections tracking curves that tight is simply begging for trouble, it doesn't matter about clearance.
gardendance wrote:Since Philly went for non-articulated 2 truck cars, I'm betting that they must have felt articulated cars, and presumably low floor articulated cars, aren't worth the effort.
I'm also assuming that whatever insurmountable clearance issues they might have are in the tunnel. I'd imagine straightening a curve would be a lot easier on the street surface than in the subway.
Those twin-bogie 'cars were bought back in the 1980s when low floor trams were still in an early stage of development and as far as North Americans and Australaisians were concerned, science fiction. I'll find out more about the 15t and whether shorter versions are available. And how hard would it be to straighten a right angle curve at an intersection?

wigwagfan wrote:Maybe if the streetcar craze grows, we'll see more than one Streetcar manufacturer. Maybe well see Inkeon enter into an actual partnership so that any of its European spec cars can be easily built here in the U.S. Maybe we'll see Bombardier open up a U.S. plant for its streetcar that it had demonstrated in Vancouver, BC during the Winter Olympics. I believe Europe has some excellent rolling stock available - the Bombardier Talent is one of my favorite DMU designs, but I won't see it here in the U.S.
1. It depends on what you mean by European spec because North American versions will be built to meet North American, not European conditions.
2. Bombardier's on street trams aren't as good (at least by technological aspects) as the Skoda. Bombardier only offers fixed bogies trams, which, even though well designed, will require easing of curves at great cost and inconveniance, not to mention grief surrounding building demolition. Or they offer pivoting bogie part high floor designs. But as far as I know, their DMU and EMU designs are just great.
  by Myrtone
It's been a while since anyone has posted in this thread. Skoda has demonstrated the ForCity in Chemitz.

  by Myrtone
In Melbourne we are getting another pivoting bogie low floor tram with ramp access to raised ailes, this time from Bombardier, I call it the Flexity Melbourne.
  by djlong
When I visited Dublin, I *loved* the Alstom Citadis trams they had running there. Previous to that, my experience with light-rail was limited to Boston's Green Line, the Baltimore Light Rail line to Camden Yards and, in the late 1960s, the PCCs that ran on San Francisco's MUNI.
  by Myrtone
By the way the Dublin Citadis that would have already been running when you were there has pivoting bogies with part high floor, there is another with full low floor but fixed bogies. Alstom does now offer Ixege bogies which do pivot under 95% low floor, one type is already in service in Istanbul. Apparently the Citadis spirit appears to have them too, as well as meeting the buy America requirements.
Meanwhile, Skoda has received orders for the ForCityPlus from Bratislava, which is ordering it in both the uni and bidirectional form.
  by dowlingm
Dublin was also new build so some curve configs could be simply avoided rather than inherited, albeit in a medieval city with a street layout unhelpful to light rail designers ;)
  by Myrtone
While Dublin was not continuing with the use of their previous Irish (5'3'') gauge tramways, nor reusing parts of them, they did reuse part of a railway built to that same gauge, which seemed to help them avoid such curve configs. But they built the new system to a narrower gauge than before consequently changing down the railway, all because Alstom isn't tooled for any other gauge. It's basically a cop out, if they had either kept even one first generation tramline open, or built a new system to the same gauge as before (the (long term) result of either way would be pretty similar), they could have reused that railway without regauging, let alone changing down.
  by dowlingm
The former heavy rail line was only on Line B, the former Harcourt Street line, the trackage of which was lifted in 1960. Line A/C reused no existing railbed. The last tram ran in Dublin city centre in 1949. (The Howth tram, in a suburb, stopped in 1959). In light of that I think it was fair enough to dispense with notions of broad gauge LRVs which would have complicated and added cost to the rollout.

EDIT: another former heavy rail line, to Broadstone station, will be used for Line D which is scheduled to open in 2017. But again, this line is 50 years closed (1961) and the terminus is a city bus garage.
  by Myrtone
One out of three lines taking over a former railways line, that's still a quite a high portion of the entire network. There were two reasons it was considered fair enough to dispense with the notion of broad gauge LRVs, one is that that neither the former tram tracks nor the Harcourt street line where there to be reused, the other is that Alstom isn't tooled for anything but standard gauge.