Green Maned Lion
Engineer
They run GrandLuxe?
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Yup, that's what helped to prompt the name change was CRC's aquiring the company.
battalion51
Engineer
I hate to bring this topic back, but there's a significant difference in the way the RDCs were built vs. the DMUs. The RDCs were built back in the days when rail cars were built well, and by someone who knew what the heck they were doing. The DMUs are a different story. Given todays modern commuter operation where every second counts, building a car that takes forever to accelerate, and has trouble making grades is an issue. Locomotives provide a great deal of horsepower to get the train up and running, and great blended braking when you need to set the train down, something the DMU can't. There's a reason why nearly every agency (outside the Northeast) uses Bombardier Bi-Levels, they work.
I'm trying to figure out why this is the case.
The Budd RDCs had two 275hp Detroit Diesels driving the wheels via a hydraulic torque converter.
The CRC DMUs have two 600hp Detroit Diesels driving the wheels via a hydraulic torque converter.
The specs seem to indicate the modern units should be better in nearly every respect.
The only thing I can figure is that the new DMUs are designed to be able to pull up to two unpowered coaches. If a commuter railroad opts for this, then perhaps the performance would suffer. But if a railroad uses only powered coaches, the specs show they should have absolutely no problem getting up to speed.
Maybe there's something I don't know...
(I'm not disputing that acceleration is an issue--Wikipedia details that it actually is an issue in practice--simply that I'm not entirely sure why it would be. That article says it was when Tri-Rail was running one powered coach and one unpowered cab car and that it's less of an issue now with two powered cars and one unpowered car, but it's apparently still an issue...)
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Simply put you can't put the power(2 x 600 minus HEP) to the rail on a railcar, the weight is not there and its after all not a locomotive.
Putting 2400 hp on a 3 car train negates the fuel savings that CRC is so poud of.
todays third generation commuter locomotives save far more fuel than CRC had hoped for.
Putting 2400 hp on a 3 car train negates the fuel savings that CRC is so poud of.
todays third generation commuter locomotives save far more fuel than CRC had hoped for.
battalion51
Engineer
There's two big differences. The RDCs aren't trying to pull unpowered trailers. The DMUs are also much larger vehicles. The DMUs are bi-level, and probably carry at least twice as many people as an RDC. So if you put them on a level playing field of HP per passenger, with the RDC carrying 90 and DMU carrying 190.
3-Car RDC (all powered) (275*2*3)/(90*3)=~6.1 hp/person
3-Car DMU (2 powered-1 unpowered) (600*2*2)/(190*3)=~4.21 hp/person
Can't argue the math.
3-Car RDC (all powered) (275*2*3)/(90*3)=~6.1 hp/person
3-Car DMU (2 powered-1 unpowered) (600*2*2)/(190*3)=~4.21 hp/person
Can't argue the math.
George Harris
Engineer
But what is the horsepower per ton of loaded vehicle?
More importantly for acceleration: What is the horsepower per ton on powered axles?
At low speeds, it gets to simply what is the weight per powered axle? Either power plant could theoretically spin the wheels at low speeds because the adhesion ratio would be exceeded.
Green Maned Lion
Engineer
I got the impression that the RDCs were stainless steel, and that the DMUs are not. I'd imagine that the RDCs are lightweight shot-welded vehicles, since they are Budds. IIRC, the DMUs are carbon-steel. Carbon steel rusts, and as a result, to offer long term structural integrity, the steel would have to be much thicker. Also, IIRC, Budd cars are unitary, although I might be thinking simply of the Amfleets. Unitary construction is inherently lighther.
Finally, the CRC cars are ever so proud of their vast amount of glass area. Glass is uber heavy.
Finally, these cars are bi-levels, of the second-story-stacked-on-top variety. These things probably weigh more than a Superliner. They certainly are bigger.
A three car DMU set would hold 570 people, and run 2400 horsepower. The RDC, to hold 570 people, would need 6 and 1/3rd, or 7, carriages. This 7 car train would have 3,850 horse power, and, I suspect, weight not all that much more.
Finally, the CRC cars are ever so proud of their vast amount of glass area. Glass is uber heavy.
Finally, these cars are bi-levels, of the second-story-stacked-on-top variety. These things probably weigh more than a Superliner. They certainly are bigger.
A three car DMU set would hold 570 people, and run 2400 horsepower. The RDC, to hold 570 people, would need 6 and 1/3rd, or 7, carriages. This 7 car train would have 3,850 horse power, and, I suspect, weight not all that much more.
Joel N. Weber II
Engineer
Does that mean that there exist locations where the tracks used to be maintained to higher standards than they are now (which would totally not be surprising), or does that mean that an RDC would actually run just fine at 50 MPH on tracks that the FRA would limit to 20 MPH?
Also, how do you ever get any significant amount of 20 MPH track these days? Class 1 only allows 15 MPH for passenger trains, and Class 2 allows 25 MPH for freight and 30 MPH for passenger trains. Dark territory is potentially allowed 59 MPH, so it's not a signaling issue. It is certainly possible to construct a curve whose speed limit is 20 MPH, but there can't be all that much track whose curve puts it right at 20 MPH. I guess railroads are allowed to set more conservative speed limits than the FRA requires.
Green Maned Lion
Engineer
Of course they are. Its there railroad.
jis
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I loved it on the NS's joint rail between Charlottsville and Charlotte. Their jointed rail track is in superb shape. CSX's welded rail track felt like a gravel path in comparison.
George Harris
Engineer
jis
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They must have installed special "clickety-clackers" for the audio effect on the welded rails then
Baseball cards maybe? :lol: :lol: :lol:They must have installed special "clickety-clackers" for the audio effect on the welded rails then
The whole Central Florida Commuter Rail issue is now in doubt. The State of Florida has lots and lots of sand and right now the Florida Legislature appears to be checking out the depth of that sand with their heads. If they can be equated to horses, with the horses' heads in the sand, the other end of the horse is now very prominent.
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Here's a couple of stories on the Orlando commuter rail saga.
http://www.news-journalonline.com/NewsJour...03POL050308.htm
http://www.orlandosentinel.com/community/n...0,3111507.story
http://www.news-journalonline.com/NewsJour...03POL050308.htm
http://www.orlandosentinel.com/community/n...0,3111507.story
Green Maned Lion
Engineer
Another case of CSX wanting to remove liability for their notoriously lax safety and maintnence?
M
Myrtonos
Guest
*************** NOTE - From a 2007/2008 Thread ***************************
But it doesn't seem they could run on electrified tracks, in order to allow that, the overhead wires would need to be higher than usual, demanding custom made gantries, and would require any single decker electric trains (as well as all electric locomotives) to have either pedestals or very tall and thus custom made pantographs. I wonder if non-standard overhead wire maintenance support equipment would also be needed.
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