Can anyone translate this sentence in the section on delays with the Venture cars: "Without that supplier's tables, which provide passenger restraint in case of an accident, the cars ... could not be placed in service"?
And any thoughts on why you would modify several hundred track miles of catenary rather than fix the pantographs on the Acelea 2 trainsets?
PassengerTrainManAnd any thoughts on why you would modify several hundred track miles of catenary rather than fix the pantographs on the Acela 2 trainsets?
You could build a pantograph that tracks fixed-tension catenary above Amtrak track structure at 'achievable' HSR speed (over 125mph sustained). It would involve three separate servo systems with active use of wing-in-ground-effect to position the light flying head relative to the wire. Predictive sensing to determine developing modes of vibration and try to break them. That's under good conditions with no ice on the wires...
Many HSR trains around the world currently run up to 220mph indicated without that kind of sophisticated complexity... but they don't try it on fixed-tension.
Note that substantial portions of the Gibbs and Hill electrification are pushing 100; large parts of the older New Haven electrification have been rebuilt and are in process of improvement to constant-tension. Since much of the infrastructure is likely needing substantial replacement (it was designed around 80mph steady passenger work) it makes sense to adapt it to future high speed and far less 'tetchy' maintenance and repair.
Apparently the table edge was responsible for severe injuries in some accidents and the Amtrak inspired specifications required a thick edge and, as I recall, a deceleration crush component. I have no idea what the supplier’s problems were.
As for the pantographs, maybe it has something to do with reducing the high cost of maintenance. If you increase the pantograph contact pressure, you increase the amount of wear on the replaceable contact. I think I saw a video on this maintenance. Changing to constant tension catenary is a better solution, as explained by Overmod above.
I have not read the Trains article yet and was therefore withholding comment, but I get the impression they were channeling the idea of seat belts without discriminating some multiple things the belts do. To me, "passenger restraint" is holding passengers in position, which is not what the table does other than circumstantially. What is involved here is passenger deceleration, the function the inertia reels (and pyrotechnic pre-tensioners) in shoulder seatbelts and harnesses are intended to assist with. As a table edge is dangerous to encounter in an impact for a variety of reasons, it is valuable to design them with a soft and rounded edge backed by CEM of the right kind.
This may not be obvious, but interior crash management only has to decelerate the effective mass of the passenger, not any part of the mass of the train. The human body does not handle impact or rapid deceleration well in many respects -- aortic dissection being one critical issue even in relatively slow impacts if the external chest is not smoothly decelerated relative to the 'aortic arch'. Padding is of limited help if it 'bottoms' before that deceleration is achieved down to levels the body can endure.
The upper abdomen, where most unbelted 'impact' of an unbelted passenger seated at a table would likely occur, is full of structures that can be damaged, often in life-threatening ways, by an impact with local concentration of "decelerative" force, or without proper CEM over the range of compression or 'crush' to get the way off the whole of the person first to a relative stop, and then to whatever absolute stop the train subsequently achieves -- which may involve subsequent accelerations and decelerations after an initial impact.
In my original development of 225mph trains, I was concerned with this issue; initial calculations indicated that 33 to 36" of controlled crush into conforming foam could do the job without aortic dissection BUT the forces involved are nonlinear and the means to dissipate them more complex...
And your development in 225 mph trains (or less) was adopted/considered where/by whom?
Jim200Apparently the table edge was responsible for severe injuries in some accidents and the Amtrak inspired specifications required a thick edge and, as I recall, a deceleration crush component. I have no idea what the supplier’s problems were.
That might be part of it but tables are part of the passenger restraint system on high speed trains to prevent the "superman" effect if the train were to suddenly stop. Alstom and other manufacturers have been using tables closely spaced to passengers as part of a restraint system for a while now.....at least two decades or more. They do not require padding to be used as a restraint either. They just need to hold the passengers without snapping off at the base.
CMStPnP Jim200 Apparently the table edge was responsible for severe injuries in some accidents and the Amtrak inspired specifications required a thick edge and, as I recall, a deceleration crush component. I have no idea what the supplier’s problems were. That might be part of it but tables are part of the passenger restraint system on high speed trains to prevent the "superman" effect if the train were to suddenly stop. Alstom and other manufacturers have been using tables closely spaced to passengers as part of a restraint system for a while now.....at least two decades or more. They do not require padding to be used as a restraint either. They just need to hold the passengers without snapping off at the base.
Jim200 Apparently the table edge was responsible for severe injuries in some accidents and the Amtrak inspired specifications required a thick edge and, as I recall, a deceleration crush component. I have no idea what the supplier’s problems were.
Right. For those types of seats, that is what Alstom, Siemens, Bombardier use in Europe for years and safety seating on Chinese HSR.
Overmod I have not read the Trains article yet and was therefore withholding comment, but I get the impression they were channeling the idea of seat belts without discriminating some multiple things the belts do. To me, "passenger restraint" is holding passengers in position, which is not what the table does other than circumstantially. What is involved here is passenger deceleration, the function the inertia reels (and pyrotechnic pre-tensioners) in shoulder seatbelts and harnesses are intended to assist with. As a table edge is dangerous to encounter in an impact for a variety of reasons, it is valuable to design them with a soft and rounded edge backed by CEM of the right kind. This may not be obvious, but interior crash management only has to decelerate the effective mass of the passenger, not any part of the mass of the train. The human body does not handle impact or rapid deceleration well in many respects -- aortic dissection being one critical issue even in relatively slow impacts if the external chest is not smoothly decelerated relative to the 'aortic arch'. Padding is of limited help if it 'bottoms' before that deceleration is achieved down to levels the body can endure. The upper abdomen, where most unbelted 'impact' of an unbelted passenger seated at a table would likely occur, is full of structures that can be damaged, often in life-threatening ways, by an impact with local concentration of "decelerative" force, or without proper CEM over the range of compression or 'crush' to get the way off the whole of the person first to a relative stop, and then to whatever absolute stop the train subsequently achieves -- which may involve subsequent accelerations and decelerations after an initial impact. In my original development of 225mph trains, I was concerned with this issue; initial calculations indicated that 33 to 36" of controlled crush into conforming foam could do the job without aortic dissection BUT the forces involved are nonlinear and the means to dissipate them more complex...
I have no idea what your talking about but here is a study that explains it more clearly.......
https://www.researchgate.net/publication/316349211_CRASH_SAFETY_OF_A_TYPICAL_BAY_TABLE_IN_A_RAILWAY_VEHICLE
All you really have to do is look at figure 4 to have the chills start.
I could argue a bit with their methodology, which might overstate the actual momentum the passenger in fig. 4 would develop to cause damage against the table edge, and I could argue greatly with their not discussing the subsequent deceleration forces and shocks once the 'Superman effect' has been overcome with the passenger 'bottomed' against the table structure as described. But their conclusions -- that the damage to a human abdomen or chest can be over 5x the upper bound of safely-survivable impact -- remains a sobering take-home message, quite at odds with the assertion these tables are "proven" safe.
Another problem with the PRR fixed terminal variable tension CAT is effect on other trains. PRR CAT is all tied together with a common support wire runing from one tower across all 4 tracks to opposide tower. The PRR CAT has all 4 ( sometimes as many as 6 ) tracks CAT attached to this support wire.
If an Acela has all the fancy gear attached to its pan the other tracks wires "may" act unpredictably and when another train passes the pan of the other train may snag the CAT pulling down the CAT for all 4 tracks. Now is that a very good idea.?
PRR built their CAT for 80 MPH operation. What is good for 80 MPH is not good for 160 MPH. Remember that aerodynamic resistance goes up with the cube of speed . so 1,728,000 / 3600 =480 times the air forces.
charlie hebdoAnd your development in 225 mph trains (or less) was adopted/considered where/by whom?
One thing about CEM in that era was that there was comparatively little interest in actual passenger protection. There were plenty of discussions of rounding edges, padding surfaces, reducing protrusions, etc. -- this was the age of awareness in automobile interior design that gave us common sense in steering-column design, for example -- but for aircraft speeds there seemed to be the assumption that if you actually hit something at over 200mph everyone would die anyway. I remember a discussion about aircraft experience that even seat-track retaining bolts were designed too weak to restrain seats with actual passengers strapped in them from breaking free and becoming enormous hammers against seated passengers in front of them... let alone any reasoned analysis of progressive CEM to reduce the high-speed trauma that was (even to sources available to me in those years) reasonably well characterized as early as the late 1940s as practical automobile speeds rose above 85mph.
I had some naive ideas about how trains were 'best' designed back then; for example I took as sensible the whole C.F.Adams idea that preventing telescoping was a major, major consideration if you were going to return to lightweight construction in metal fragile to off-design-access shock or in composites that might fracture into slivers. So I carefully designed connections between cars to survive very great stress and put strong framing and interlocking members in the ends of the cars. Modern CEM treats these, probably correctly, as crumple zones to reduce peak accelerations on seated passengers.
Amusingly enough, I was well aware that one of the 'better' ways to implement relatively safe deceleration was to have the passengers ride backward with their arms within the edge of the seat enclosure, and the deceleration material distributed behind the seat padding. Where did I get this? Gerry Anderson's SPV!
But I did not like the idea of making passengers ride backward, even in the name of safety...
So I read the article in Trains Magazine on the table situation, it does not read to be critical and will get addressed in a few weeks or maybe a month or two. Not sure about the overhead wire situation. At any rate, Siemens should have a giant backlog of orders by now between Brightline and Amtrak to keep it busy for the next 3 years at least and probably beyond if Amtrak expands the existing orders which is likely.
I am still holding out for the bi-level replacements for the Superliner cars and curious what the specs for those will be. I think if Amtrak goes with the Siemens bi-level sleeping car for long distance they will hit a home run and we will be finally close to being on par with Japan and Europe for the accomodations piece at least.
CMStPnPSo I read the article in Trains Magazine on the table situation, it does not read to be critical and will get addressed in a few weeks or maybe a month or two.
Not sure about the overhead wire situation.
I am still holding out for the bi-level replacements for the Superliner cars and curious what the specs for those will be.
What is a bigger surprize is that there are not more parts shortages. Siemens does have quite a few mostly finished cars parked outside the factory. It also requested that additional property it purchased be allowed for storage before rezoning application is approved. That seems to indicate a parts shortage. Hopefully it will not get into the bind that CAF did. Most of the AF problems were of their own making.
Cannot remember but did Siemens say they were bringing more parts construction in house.? That would be similar to what Boeing is doing.
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