• High Speed Rail

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

Moderators: mtuandrew, gprimr1

  by zmuzak
 
Hello,

There has been more talk of high speed rail in Illinois, and the need to upgrade track to get to those speeds over 200 mph.

What is the technical reason why the current tracks and only support 110mph? What is the difference in track for high speed rail?

Thanks.
  by eolesen
 
Several big differences....

1) At 110+, you can't have any at-grade crossings or potential for pedestrians crossing the line; Illinois is either second or third in terms of the highest number of grade crossing accidents in the country if I recall.
2) In order to maintain speed at crossovers, they need to be 2-5x longer than what is used with "classic" rail
3) Curves have to be super-elevated to keep the ride smooth and fight centrifugal forces
4) Segregation from freight
5) Lateral forces on the track -- wood with spikes or screws can't handle the increased forces. You need concrete with clips, and lots of reinforcement on the curves & turnouts to keep the track from shifting...

If you're going to do HSR right, it's got to have all three of those taken into consideration. And if you're going to build all that infrastructure, you might as well electrify it as well... ;)
  by vxla
 
eolesen wrote:Several big differences....
2) In order to maintain speed at crossovers, they need to be 2-5x longer than what is used with "classic" rail
That's if you're taking those cross-overs at speed. What's the likelyhood of taking an xover at 220mph?
eolesen wrote: 3) Curves have to be super-elevated to keep the ride smooth and fight centrifugal forces
Tilt trains will still be needed for true high speed service.
eolesen wrote: 4) Segregation from freight
There's enough room on the current CN/IC row to handle high speed service into Chicago.
  by morris&essex4ever
 
eolesen wrote:Several big differences....

1) At 110+, you can't have any at-grade crossings or potential for pedestrians crossing the line; Illinois is either second or third in terms of the highest number of grade crossing accidents in the country if I recall.
2) In order to maintain speed at crossovers, they need to be 2-5x longer than what is used with "classic" rail
3) Curves have to be super-elevated to keep the ride smooth and fight centrifugal forces
4) Segregation from freight
5) Lateral forces on the track -- wood with spikes or screws can't handle the increased forces. You need concrete with clips, and lots of reinforcement on the curves & turnouts to keep the track from shifting...

If you're going to do HSR right, it's got to have all three of those taken into consideration. And if you're going to build all that infrastructure, you might as well electrify it as well... ;)
For true high speed, I'd say do all of the above and of course electrify. Illinois isn't seeing true HSR anytime soon though.
  by jtr1962
 
For speeds over about 110 mph, you probably need to electrify. You definitely need to for 200 mph speeds. It's probably a good idea to do so anyway on any moderately busy freight or passenger line, regardless of speeds, because in the long term you have much lower operating costs than diesel ( and also no emissions ).
  by morris&essex4ever
 
jtr1962 wrote:For speeds over about 110 mph, you probably need to electrify. You definitely need to for 200 mph speeds. It's probably a good idea to do so anyway on any moderately busy freight or passenger line, regardless of speeds, because in the long term you have much lower operating costs than diesel ( and also no emissions ).
BNSF was considering electrification a few years ago. Anyone know if they still are?
  by jtr1962
 
morris&essex4ever wrote: BNSF was considering electrification a few years ago. Anyone know if they still are?
I haven't heard anything new since late last year, when they were mostly in the discussion phase. I think whether or not it will happen depends upon several factors. One is how much the price of diesel rises. Another is whether or not carbon taxes are passed. This would be a very long-term project, likely taking well over a decade, and costing up to $10 billion. BNSF won't jump into it without thoroughly analyzing the pros and cons.
  by eolesen
 
vxla wrote: That's if you're taking those cross-overs at speed. What's the likelyhood of taking an xover at 220mph?
220? Probably not likely. But in normal service, I've experienced 90 or so in the UK, and I'm sure there are sections where 70+ are done on the NEC.
  by Matt Johnson
 
eolesen wrote: 220? Probably not likely. But in normal service, I've experienced 90 or so in the UK, and I'm sure there are sections where 70+ are done on the NEC.
The highest speed crossovers on the NEC have an 80 mph diverging speed. The fastest turnout I've heard of is 220 km/hr (137 mph) - I believe you'll find those in France.
  by 130MM
 
Matt Johnson wrote:
eolesen wrote: 220? Probably not likely. But in normal service, I've experienced 90 or so in the UK, and I'm sure there are sections where 70+ are done on the NEC.
The highest speed crossovers on the NEC have an 80 mph diverging speed. The fastest turnout I've heard of is 220 km/hr (137 mph) - I believe you'll find those in France.
In case anyone is interested, the frogs on the NEC crossovers are #37.7775.

DAW
  by Nasadowsk
 
Matt Johnson wrote:
eolesen wrote: 220? Probably not likely. But in normal service, I've experienced 90 or so in the UK, and I'm sure there are sections where 70+ are done on the NEC.
The highest speed crossovers on the NEC have an 80 mph diverging speed. The fastest turnout I've heard of is 220 km/hr (137 mph) - I believe you'll find those in France.
186mph, not diverging. You don't even feel them.
  by Matt Johnson
 
Nasadowsk wrote: 186mph, not diverging. You don't even feel them.
Right, I mean 220 km/hr diverging! You don't really feel the newer crossovers with the moveable point frogs on the NEC either...the Acela runs over those at 150 mph.