Are cab cars, DMUs a safety problem?

[tomikawaTT]

Back to the original subject...

Just saw a (copyrighted, unfortunately) photo of a recently-built Japanese private railway EMU set.  The 'interior' cars were of conventional appearance.  The cabs looked as if they were inspired by Darth Vader's helmet!  Obviously built of something approximating naval armor plate, the lower edge of the rather sharply angled pilot all but scraped the railheads.  Just below cab window level, there was a 'fence' of protruding studs, obviously intended to keep anything impacted at a grade crossing from climbing into the driver's operating space.  If that thing hit an SUV, it would punt it into the next county.

That particular EMU set would be an acute safety problem to anything or anyone that got in its way - but not to the driver or riders.

Chuck

[martin.knoepfel]

There are several high-speed EMUs in Western Europa, for example the ICE 3 in Germany (actually out of service because on one train, an axle broke, reasons not yet clear). The Italian Pendolinos and their British  version are EMU's oder DMU's, too. Of course, there are o grade level crossings on proper HS-ROW.

France, Switzerland and Britain (and IIRC Germany too) run conventional push-pull-trains with a driving-trailer at one end and the engine at the other. Top-speed 100 mph. I rode some and did not feel scared. 

[passengerfan]

Over the years I have sampled many trains and planes when they accelerate and can't help but recall returning one Sunday evening from Phoenix to San Diego my first time on Western Airlines (The only way to fly). I had taken the United 727 flight on many occasions so was rather surprised to see our flight was a 4 - engined Turbo Prop Electra. When we taxied out to the runway I had no idea what I was in for. The passenger seated across the aisle from me told his buddy he would put a twenty dollar bill on the back of the headrest ahead and when the plane accelerated down the runway he could not reach forward and pick up the twenty. The United 727 that I normally flew took off just ahead of us.

The Electra turned onto the runway and I have never been pinned into my seat like that plane did on its takeoff run. I know we did not fly as high as the 727 on that flight but we arrived just ahead of the 727. All in all it was one of the few planes that have ever almost taken my breath away. That acceleration I will never forget and by the way try as the guy across from me might he was unable to reach forward for the twenty.

Fastest acceleration I can remember on a train was a CN Turbo pulled by an FPA4 that made better time from Toronto to Montreal than when the Turbo had all of its turbines operating. This was a frequent occurrance in the winter on this run as the turbines did not like the fine snow along the route and one or more turbines failed. As long as they had one for hotel power they would assign an FPA4 or FP9A for power. The MLW smoked more than a GM would have but it could sure accelerate like a scared rabbit.

Al - in - Stockton  

[JT22CW]

The F40PH is very safe although same can't be said for the Genes#!+ (Genesis?)

Is that based on fact or opinion?

remember this was caused by a SUV had a F40PH been leading that train the results would have probely been far less tragic.

For the record, that damage was not caused by hitting the SUV.  IIRC, the cab car pushed the SUV into a switch, which was thrown; the train was then derailed, and the damage was caused by hitting a freight train that was parked on an adjacent track.  If an F40PH were leading (which would not be possible since Metrolink has none), it is possible that the accident could have been more tragic, since the mass of the locomotive might have been pushed into the cars behind it after hitting the freight train.

To pull enough power from one pantograph riding one wire at 150mph, is it possible, don't know

The TGV runs both power cars at 186 mph on one pantograph.

I understand why the Acela trains have a power unit at each end it just seems to me they could put more cars between the cab ends

David Gunn once stated that he wanted to expand the length of the Acela trains to 8 or 9 cars. He assessed the six-car configuration as being "overpowered". In spite of that not being realized, it is still possible to couple two AE trainsets together to form a 12-car train, although this may not be approved in practice perhaps due to insufficient testing of high-speed runs using those couplers. (In Germany, ICE 3 EMUs are coupled together to form 16-car trains, in common practice.)

True, South of Boston and southern Rhode Island is 150 mph track, but much of the line is 135 to 140 mph limit

"Much of the line" on the PRR side has a maximum speed of 125 mph, and this is due to safety concerns regarding the still-unreplaced variable-tension wires, and possible need to upgrade the track to FRA Class 8; there are a lot of speed restrictions due to frequent curves, too. There is possibly one section that allows 135 mph, through Princeton Junction NJ. The fastest average speed of the Acela Express overall is 82 mph. I know of no location on the NEC that has a 140-mph top speed, specifically.

On Metro-North, the Acela Express is held down to speeds of about 70 mph. In spite of the AE being two inches narrower than standard stock (Budd Cosmopolitans, the coming Kawasaki M8, Amfleets, et cetera are 10' 6" wide while AE is 10' 4" wide), Metro-North will not permit Amtrak to use the active-tilt system on their rails.

Acela, alone among bullet trains, have standard 8 wheel cars coupled together

In fact, the TGV is "alone among bullet trains" in its form of articulation (the Talgo's form is quite different). The vast majority of high-speed trains have wheel arrangements like the AE, which includes all ICE trains (plus ICE-T), the X2000, the Pendolino, and IINM the Shinkansen trainsets. Also, the AE cars IIRC are "semi-permanently coupled", which implies some kind of drawbar setup.

150 mph speed is unnecessary and not sustained for any significant distance; but Amtrack got a lot of marketing mileage out of only a few miles.

For shorter base service trains, a cab control coach would be more sensible with all the horsepower in the locomotive. The same Acela nose and safety cab could be built on the end of a coach, much like the previously mentioned X2000. The X2000 runs at 125 mph with 4-5 cars, a cab coach, and an electric locomotive. A similar Acela train could have 352 seats

It's not salient to call 150 mph "unnecessary". If you're comparing the AE and the X2000, then note that SJ has been rather dogged insofar as holding onto those trainsets. They get higher average speeds than the Acela Express while running at a top speed of 125 mph (90 to 109 mph), but they also stop less frequently and actually tilt properly. Remember that most tilt trains in Europe run at a top speed of 143 mph on traditional rail corridors, and achieve (in some cases) average speeds as high as 120 mph. A top speed of 150 mph for sustained distances, with functional tilt running, could raise average speeds on the NEC (and other traditional rail corridors!) well beyond the triple-digit threshold.

[HarveyK400]

David Gunn's assessment of the Acela consist reinforces what I wrote, perhaps in the energy thread.  It also suggests that a single Acela cab-power car, five business/first class and cab-business class end car would be a reasonable consist capable of quick acceleration to 125 mph and able to reach 150 mph (for bragging rights) in short stretches 8-20 miles long.

You speak of sustained 150 mph Northeast Corridor operation with tilt technology and of a stretch through Princeton Junction, NJ where 135 is permitted.  The segment through Princeton Junction and possibly another through Newark, DE may be the only ones with tangents and 0.5-deg curves where 175 mph with tilt suspension may be attained; but, from my experience, hardly sustained long enough to save more than a minute or two.  Interestingly, the Princeton Jct. stretch is where the Turbo Train hit 170 mph on a test run. 

Most of the former Pensyvania Railroad was built to a standard of 1-degree curves that result in 10.94 inches total underbalance at 125 mph.  With 4 inches cant, the 6.94 inches deficiency is just within the Acela's design limit. 

I see no reasonable way to build a new 217mph/350kph line through the Washington, DC - New York, NY - Providence, RI conurbation.  Segments may be identified where less costly curve easement may be possible.  185 mph would require 0.457-degree, 12,600-foot radius curves with 10.94 inches underbalance.   Given the additional distance needed to accelerate to 185 mph from 125 mph and presumably short segments, 175 mph may be a more readily attainable goal.  Over 150 mph would require separate freight tracks as well; but relatively low freight limits and high cant already may have brought on separate tracks in certain areas. 

I think the challenge and priority should be to provide capacity to meet future demand.

[beaulieu]

David Gunn's assessment of the Acela consist reinforces what I wrote, perhaps in the energy thread.  It also suggests that a single Acela cab-power car, five business/first class and cab-business class end car would be a reasonable consist capable of quick acceleration to 125 mph and able to reach 150 mph (for bragging rights) in short stretches 8-20 miles long.

Harvey your suggestion of a trainset consisting of a powercar, 5 coaches, and cabcar, would essentially be a similar train to today with just one powercar. As the power cars are rated at only  4574 kW  each (6115 hp) it wouldn't be anywhere near adequate. When  David Gunn was talking about overpowered he was only talking about adding 1 or 2 cars, not halving the power to weight ratio.

[DMUinCT]

 You do know you're moving!!!

 

 

[HarveyK400]

Maybe we have a difference of opinion of what adequate performance is.  

Admittedly, my first guess was a little off.  I did some acceleration calculations a few years back; and one case in my notebook was for a 396-ton train, the rough equivalent of five cars with a 6100 hp locomotive.  The sixth car may increase the distances and times by a quarter.  A twelve-car Acela Express with two locomotive would do as well as the five-car train case.  

              Speed                 Distance               Time

           0-125 mph              4.2 miles            3.0 minutes

           0-150 mph              9.0 miles            5.1 minutes    

            

[beaulieu]

Harvey, five Acela cars plus the powercar comes to 455 tons (15 % more). Also do your figures include air drag?

[HarveyK400]

beaulieu,

MY bad - I was assuming the Acela cars would be similar to 4 apparently lighter Bombardier LRC cars, which they resemble, with two 3000 hp HST gas-turbine locos, one loco being the rough equivalent of two cars.  I used what I thought was a close example to represent the Acelas.  If you have the information and the capability, I would be interested in seeing what you would come up with.

The point is that a single 6,000 hp locomotive is capable of really good performance with a decent size train from an example without pushing around a heavy NPCC unit.  A cab coach is much more efficient; and it can be built for safety.  I really wonder if the Acela could be lighter and why it is as heavy as it is.

I assumed the weight of 274 passengers which comes to another 24 tons.

I'll repeat a source I found in Railway Gazette International for drag coefficients that I used with the traditional Davis formula: "Optimizing aerodynamics to raise IC performance," Jean-Luc Peters, Dec, 1982. 

Incidently, the default track resistance factor from the mid-1900s, 1.5 lbs/ton used by Davis, is too high for today's mainline track.  Hay referenced a KCS study where 1.5 lbs/ton for 85# rail and 0.9 lbs/ton for 140# rail were found.  I used 1.3 lbs/ton for a conservative approximation for 115# rail on the Chicago - Saint Louis corridor.  I can't find the reference that deep, good quality ballast provides around 10 times the modulus of elasticity of the rail. 

 

[DMUinCT]

  Acceleration rates are limited do to Passenger comfort.  The HP is needed to Hold Speed on curves and hills.  A locomotive hauled passenger train (MBTA) on The Corridor can lose 30mph on Sharon Hill between Boston and Providence.

  Amtrak used the same model Acceleration Meters as we use in the Elevator Industry.  While we can accelerate an elevator at 4fps/ps vertically, trains are set somewhere around 2 fps/ps so you "Don't Spill The Coffee".

[beaulieu]

beaulieu,

MY bad - I was assuming the Acela cars would be similar to 4 apparently lighter Bombardier LRC cars, which they resemble, with two 3000 hp HST gas-turbine locos, one loco being the rough equivalent of two cars.  I used what I thought was a close example to represent the Acelas.  If you have the information and the capability, I would be interested in seeing what you would come up with.

The point is that a single 6,000 hp locomotive is capable of really good performance with a decent size train from an example without pushing around a heavy NPCC unit.  A cab coach is much more efficient; and it can be built for safety.  I really wonder if the Acela could be lighter and why it is as heavy as it is.

I assumed the weight of 274 passengers which comes to another 24 tons.

I'll repeat a source I found in Railway Gazette International for drag coefficients that I used with the traditional Davis formula: "Optimizing aerodynamics to raise IC performance," Jean-Luc Peters, Dec, 1982. 

Incidently, the default track resistance factor from the mid-1900s, 1.5 lbs/ton used by Davis, is too high for today's mainline track.  Hay referenced a KCS study where 1.5 lbs/ton for 85# rail and 0.9 lbs/ton for 140# rail were found.  I used 1.3 lbs/ton for a conservative approximation for 115# rail on the Chicago - Saint Louis corridor.  I can't find the reference that deep, good quality ballast provides around 10 times the modulus of elasticity of the rail. 

 

Harvey I'm afraid its been too long since my math days without much use, for me to solve those equations. I just realized that you were using too low a weight and that it would skew the results.  As far as why they are so heavy, I think it's a price we pay here in the US for fact that we challenge the train at grade crossings, and for the very heavy freight trains, with the result that passenger trains have to be much heavier and consume more energy, whether that energy is electricity or diesel. This wasn't much of a problem when energy was cheap, but we are paying the price now. I look at the Acela, and then at the TGV Duplex, and its pretty sad comparison.

 Using metric measure

Acela weight   566 tonnes

Duplex weight  380 tonnes

 

Acela power     9.2 MW

Duplex power    8.8 MW

 

Acela capacity  304 passengers

Duplex capacity 516 passengers

 

Acela length (w/6 cars) 202 metres

Duplex length (w/8 cars) 200 metres

 

Acela weight per seat  1.9 tonnes per seat

Duplex weight per seat 0.73 tonnes per seat

 

Acela power to weight   16.3 kW per tonne

Duplex power to weight  23 kW per tonne

 

Acela power to seat     30.3 kW per seat

Duplex power to seat    16.2 kW per seat

 

Pitiful

John Beaulieu 

[HarveyK400]

I would have imagined passenger discomfort was more likely to register beyond the adhesion limit of the train.  I'm a little surprised that Amtrak measured acceleration and surveyed passengers for this issue.  More uncomfortable and likely to spill coffee are the sudden jerks starting and stopping.  

Curve resistance is pretty insignificant for a small passenger train on the NEC.  This is not Raton Pass and the Southwest with 10-15 express cars.

Now grades can be another matter.  I was unaware of any substantial grades beside Hell Gate Bridge and the East and Hudson River Tunnels on the NEC.  Even so, the power to accelerate rapidly to 150 mph isn't over-taxed in maintaining that speed on moderate grades.  Acceleration on such a grade, however, would be drawn out. 

My observation of the MBTA 20+ years ago was that trains were short, 4-6 light weight Bombardier cars.  It's hard to think there would be any problem with grades.

The North Western had an 11-car train weighing around 960 tons with an E8 and passengers that could do not much better than 45 mph upgrade from a stop at Arlington Heights to Barrington. 

 

[oltmannd]

The HP for the Acela trainsets came from working backwards from a mandated running time.  If you keep bumping up the HP/ton, you keep shortening the running time.  Not always so much because of trying to hold speed on grade or attaining a high maxiumum speed, but because recovery from reduced speed is faster.

The law of diminishing returns is in full working order with the Acela trains, though.  They had to bump the HP/ton waaay up in order to shave those last few minutes to reach the mandated running time. 

I think what Gunn was getting at was that a common sense approach would have allowed considerably lower HP/ton with only a small sacrifice in running time.  Either longer or single ended train sets might have made more sense.  It was a bad mistake for Congress to mandate a running time in the legislation.

The remarkable thing is, that for all their flaws, Acela does really well economically.  Those 20 train sets are pulling in ~25% of Amtrak's revenue.

[DMUinCT]

  MBTA, average 6 to 8 cars now, about half Double Deckers. F40PH or GP40MC on the point.

  The Ruling Grade north of New York is at Sharon Mass. as you climb from Boston Harbor, across the 170 year old Canton Viaduct, up Sharon Hill and then down to Providence on Narragansett Bay.   No problem for an Acela at carded speed.

[JT22CW]

beaulieu,

MY bad - I was assuming the Acela cars would be similar to 4 apparently lighter Bombardier LRC cars, which they resemble, with two 3000 hp HST gas-turbine locos, one loco being the rough equivalent of two cars.  I used what I thought was a close example to represent the Acelas.  If you have the information and the capability, I would be interested in seeing what you would come up with.

The point is that a single 6,000 hp locomotive is capable of really good performance with a decent size train from an example without pushing around a heavy NPCC unit.  A cab coach is much more efficient; and it can be built for safety.  I really wonder if the Acela could be lighter and why it is as heavy as it is.

I assumed the weight of 274 passengers which comes to another 24 tons.

I'll repeat a source I found in Railway Gazette International for drag coefficients that I used with the traditional Davis formula: "Optimizing aerodynamics to raise IC performance," Jean-Luc Peters, Dec, 1982. 

Incidently, the default track resistance factor from the mid-1900s, 1.5 lbs/ton used by Davis, is too high for today's mainline track.  Hay referenced a KCS study where 1.5 lbs/ton for 85# rail and 0.9 lbs/ton for 140# rail were found.  I used 1.3 lbs/ton for a conservative approximation for 115# rail on the Chicago - Saint Louis corridor.  I can't find the reference that deep, good quality ballast provides around 10 times the modulus of elasticity of the rail. 

 

Harvey I'm afraid its been too long since my math days without much use, for me to solve those equations. I just realized that you were using too low a weight and that it would skew the results.  As far as why they are so heavy, I think it's a price we pay here in the US for fact that we challenge the train at grade crossings, and for the very heavy freight trains, with the result that passenger trains have to be much heavier and consume more energy, whether that energy is electricity or diesel. This wasn't much of a problem when energy was cheap, but we are paying the price now. I look at the Acela, and then at the TGV Duplex, and its pretty sad comparison.

 Using metric measure

Acela weight   566 tonnes

Duplex weight  380 tonnes

 

Acela power     9.2 MW

Duplex power    8.8 MW

 

Acela capacity  304 passengers

Duplex capacity 516 passengers

 

Acela length (w/6 cars) 202 metres

Duplex length (w/8 cars) 200 metres

 

Acela weight per seat  1.9 tonnes per seat

Duplex weight per seat 0.73 tonnes per seat

 

Acela power to weight   16.3 kW per tonne

Duplex power to weight  23 kW per tonne

 

Acela power to seat     30.3 kW per seat

Duplex power to seat    16.2 kW per seat

 

Pitiful

John Beaulieu 

Did you get that comparison from Trainweb?  I never saw the point.  The TGV Duplex was built for 186-mph operation on dedicated high-speed corridors (LGVs); it was not meant for tilt-train operation on traditional rail networks, and when operating on traditional rail networks, it has to run at track speed (which is higher than the USA, at 137 mph, on the best traditional lines).  Also, IINM, the TGV Duplex may be a little too tall to run on the Northeast Corridor (IIRC, it may be over 15 feet tall, which is a bit too tall for the tunnels in NYC) and they can only use low platforms (which would make them ideal for something like the California HSR proposed system).

A better comparison would be Acela Express to ICE 1 (a more even weight comparison); but even that is not parallel.  Not to mention, the AE is not heavy when compared with other trains that have operated in the USA; the power cars are only 2,000 lbs heavier than the AEM-7, and the trailer cars are actually lighter than the PRR's MP54-E6.  (Also, this is anecdotal, but some rails I've corresponded with insist that the power car HP of the AE is actually 8,000, same as the HHP-8.)

[Ham549]

This video should leave no doubt in your minde that a F40PH is safer than a cab car

http://youtube.com/watch?v=HZWpeU55J3E

Hell a F40PH is safer than a genes#it while cabbages take out loaded dumptrucks P42's derail when ramming tow trucks. 

[beaulieu]

This video should leave no doubt in your minde that a F40PH is safer than a cab car

http://youtube.com/watch?v=HZWpeU55J3E

Hell a F40PH is safer than a genes#it while cabbages take out loaded dumptrucks P42's derail when ramming tow trucks. 

All that proves is that the crash standards in the 1970s were higher than those in the 1960's. An F40PH  won't meet current crash standards and neither will a Genesis. That is why the Wabtec MPExpress is the only commuter locomotive being built. Whether or not a locomotive derails when it hits a truck depends on whether the truck crushes and goes under the locomotive lifting it of the rails, a loaded dump truck with the high center of gravity will tend not to go under the locomotive as long as it doesn't break apart too quickly.

[JT22CW]

That video proves nothing.  Not too mention, vehicles in motion crashing into stationary vehicles seem to always exhibit that "climbing" behavior.  Note this "heavy" locomotive (heavier than an F40PH; look at the six axles, which indicates between 40 to 50 tons on the F40PH) slamming into stationary coal cars:

http://www.youtube.com/watch?v=mUF19acPBZA