catenary

[Joel N. Weber II]

That probably mostly depends on the radius of curves encountered.

It also depends how how closely the tracks are spaced and how much money Caltrain is willing to spend on maintaining the tracks to high speed standards and what the capabilities of the signaling system are and what the maximum speed of the equipment used for the Baby Bullet is and the quality of the crossings of automobile roads and maybe some other things I'm forgetting.

But curve radius is often not something you can easily throw money at fixing if there happen to be a large quantity of buildings in the place where you might want a large radius curve, whereas most of the rest of the factors are pretty much a simple matter of money.

 

[Green Maned Lion]

Top speed would probably not increase. Acceleration, however, very likely would.

 

[Crescent ATN & TCL]

Also, true the locomotives run on electricity, but where does it come from? :huh: Most likely from burning oil or gas! And at least on the NEC, the voltage that runs through the wires is 25,000 volts!
It makes sense in a high capacity corridor (like the NEC) to electrify. (At my station in KIN, I can expect to see at least 1 train an hour - not all of them stop - on average from 6:30 AM to 11 PM.) But it would not make sense in MT or AZ, where there is 1 train a day - or less!

Actually it would make sense. Freight Railroads aren't opposed to electrification, many are looking into it with soaring fuel cost, but right now more focus is on increasing capacity. If congress got on board and issued grants electrification would be a good possibility.

 

[PRR 60]

....The wire will be higher above the rail than in the Northeast, as there is the need to be able to run double stacks under it, at least south of San Jose, and possibly high clearance for freight for most of the distance north of there.

The proposed Caltrain nominal contact wire height above top of rail, 22 feet, is exactly the same as the original PRR design in the NEC and the existing Amtrak clearance. The difference would be the absence of contraints to the nominal clearance. In the NEC the contact wire height is as low as 15' 8" inside the tunnels. Caltrain would not have any limiting areas like that.

 

[gswager]

That's what I thought, the speed would be the same, but the torque is greater (speed up).

 

[Joel N. Weber II]

Better acceleration will probably make the schedule a bit faster, though, especially on the trains that make more stops. And we have another thread showing that top speed has little to do with overall trip time; the Acela Express averages 69 MPH from BOS to WAS, in spite of the more commonly cited maximum speed of 150 MPH.

On the non-Acela trains, Amtrak's usual diesel (the P42) is capable of 110 MPH, and the electric locomotives used on the Regional and Keystone trains can do 125 MPH. But if the Baby Bullet isn't reaching 110 MPH, the reason for that probably isn't entirely the limitations of diesels. On the other hand, accelerating to higher speeds may make sense for shorter stretches of electrified track than track where diesels are pulling the trains.

 

[Green Maned Lion]

They have higher horsepower and higher torque. For instance, a P42 has 4200bhp whilst the HHP-8s have 8000, the Acela has 2x 6000, and AEM-7 locos have 7000. Moreover, the bhp of the electrics are strictly for tractive effort. The HEP provision is seperate. If we were to combine the horsepower for motive traction with the HEP, a total of around 6Mw, we'd get more like 8050 hp.

The point being, an electric engine allows a smaller trainset. An AEM-7AC or HHP-8 can pull a twelve car train. The Empire Builder, a 12 car train, requires THREE P42s. So basically, the single electric can do the job of 3 P42 diesels. Put it another way, NJTransits single engine Comet VI trains can pull 10 cars, a total of about 1400 people can be hauled with a single engine.

 

[PRR 60]

They have higher horsepower and higher torque. For instance, a P42 has 4200bhp whilst the HHP-8s have 8000, the Acela has 2x 6000, and AEM-7 locos have 7000. Moreover, the bhp of the electrics are strictly for tractive effort. The HEP provision is seperate. If we were to combine the horsepower for motive traction with the HEP, a total of around 6Mw, we'd get more like 8050 hp.
The point being, an electric engine allows a smaller trainset. An AEM-7AC or HHP-8 can pull a twelve car train. The Empire Builder, a 12 car train, requires THREE P42s. So basically, the single electric can do the job of 3 P42 diesels. Put it another way, NJTransits single engine Comet VI trains can pull 10 cars, a total of about 1400 people can be hauled with a single engine.

The last time I was on the EB, it used two P42's which ran through to Seattle. The Portland section ran with one.

 

[Joel N. Weber II]

The point being, an electric engine allows a smaller trainset. An AEM-7AC or HHP-8 can pull a twelve car train. The Empire Builder, a 12 car train, requires THREE P42s. So basically, the single electric can do the job of 3 P42 diesels. Put it another way, NJTransits single engine Comet VI trains can pull 10 cars, a total of about 1400 people can be hauled with a single engine.

The number of cars on a train is not the only factor in locomotive sizing. The grades on the route are also a factor. Do we have any evidence that the steepest grade on the NEC is the same as the steepest grade on the Empire Builder?

(The frequency of curves and frequency of stops might also influence decisions about how much acceleration is desired in theory, though I suspect in the real world the people who make the schedules are willing to run the trains a little slower instead of throwing an extra locomotive into the consist.)

 

[Dutchrailnut]

The point being, an electric engine allows a smaller trainset. An AEM-7AC or HHP-8 can pull a twelve car train. The Empire Builder, a 12 car train, requires THREE P42s. So basically, the single electric can do the job of 3 P42 diesels. Put it another way, NJTransits single engine Comet VI trains can pull 10 cars, a total of about 1400 people can be hauled with a single engine.

The number of cars on a train is not the only factor in locomotive sizing. The grades on the route are also a factor. Do we have any evidence that the steepest grade on the NEC is the same as the steepest grade on the Empire Builder?

(The frequency of curves and frequency of stops might also influence decisions about how much acceleration is desired in theory, though I suspect in the real world the people who make the schedules are willing to run the trains a little slower instead of throwing an extra locomotive into the consist.)

Your right Joel a single AEM7ac or HHP-8 would have a hard time with 8 cars in mountenous terain, compared to NEC.

A single engine could never put the ponies to the rail so to speak, it would be sitting there spinning its wheels.

 

[Green Maned Lion]

That is a point to consider, I'll admit. However, my point does stand, and... the grade out of Penn isn't exactly flat!

 

[Neil_M]

Don't forget, electric locos are generally lighter than diesel locos. Might be great to have all that HP on tap, but if its raining and the rail condition is less than ideal then its wheelslip time.....

Even when on the move, a bout of high speed wheelslip can cause lots of damage to wheelsets and traction motors unless it is arrested fairly quickly.

 

[AlanB]

Don't forget, electric locos are generally lighter than diesel locos. Might be great to have all that HP on tap, but if its raining and the rail condition is less than ideal then its wheelslip time.....Even when on the move, a bout of high speed wheelslip can cause lots of damage to wheelsets and traction motors unless it is arrested fairly quickly.

Electric locos aren't all that much lighter than their diesel counterparts. Those transformers that convert 25kV into usable power aren't all that much lighter than the actual diesel motor.

A quick glance at Amtrak's roster shows only about a 47,000 pound difference between an HHP and a P42. And when both weight over 200,000 pounds, 47,000 aren’t that much of a difference. And I'm sure if the need arose, that a few extra pounds could be squeezed into the HHP. And the P42 is the heaviest diesel loco that Amtrak operates on the road.

 

[Neil_M]

Don't forget, electric locos are generally lighter than diesel locos. Might be great to have all that HP on tap, but if its raining and the rail condition is less than ideal then its wheelslip time.....Even when on the move, a bout of high speed wheelslip can cause lots of damage to wheelsets and traction motors unless it is arrested fairly quickly.

Electric locos aren't all that much lighter than their diesel counterparts. Those transformers that convert 25kV into usable power aren't all that much lighter than the actual diesel motor.

A quick glance at Amtrak's roster shows only about a 47,000 pound difference between an HHP and a P42. And when both weight over 200,000 pounds, 47,000 aren’t that much of a difference. And I'm sure if the need arose, that a few extra pounds could be squeezed into the HHP. And the P42 is the heaviest diesel loco that Amtrak operates on the road.

There isn't that much difference over this side of the Atlantic, most of our electric locos weight in around 80 tons and diesels around 120-130 tons, but the large difference in HP means that electrics are more prone to slipping, although modern traction control is a lot better than the older systems of control.

 

[jackal]

Don't forget, electric locos are generally lighter than diesel locos. Might be great to have all that HP on tap, but if its raining and the rail condition is less than ideal then its wheelslip time.....Even when on the move, a bout of high speed wheelslip can cause lots of damage to wheelsets and traction motors unless it is arrested fairly quickly.

Electric locos aren't all that much lighter than their diesel counterparts. Those transformers that convert 25kV into usable power aren't all that much lighter than the actual diesel motor.

A quick glance at Amtrak's roster shows only about a 47,000 pound difference between an HHP and a P42. And when both weight over 200,000 pounds, 47,000 aren't that much of a difference. And I'm sure if the need arose, that a few extra pounds could be squeezed into the HHP. And the P42 is the heaviest diesel loco that Amtrak operates on the road.

Well, the weight of the locomotive itself might not be a huge factor, and those 25kV transformers might be really heavy, but the same weight in 25kV transformers outputs a lot more power to the traction motor than the equivalent weight of diesel combustion engines. In other words, the power-to-weight ratio is much higher in an electric locomotive--for a given weight, much more (more than twice as much) electricity is transferred to the traction motors.

This makes things more efficient, but it can also cause wheel adhesion problems. Almost twice as much tractive effort out of four axles that are being pushed down onto the rail with 47,000 pounds less force (47,000 pounds out of 200,000 pounds is almost 25% less--not insignificant) is a perfect recipe for wheel slippage in less-than-ideal conditions.

Personally, I'm a fan of big freight power of the kind not even comprehended in Europe: I know from personal experience (a placard in the cab) that an Alaska Railroad SD70MAC with HEP weighs 425,000 pounds (212 short tons or 192 long tonnes). With six axles supporting all that weight, wheel slippage isn't much of a problem, no matter how steep and wet things get! :lol:

 

[Dutchrailnut]

That is a point to consider, I'll admit. However, my point does stand, and... the grade out of Penn isn't exactly flat!

Comparing the less than 1 mile long grade at NYP with any of the grades out west is absolutly no- comparison.

The AEM-7 and HHP-8 are light footed even with 8 cars on reletively flat NEC, biggest complaint from any Amtrak engineer, wheelslip.

The enviroment in a tunnel is pretty much controlled, no rain, no leaf residue, no ice , no snow, so again no comparison to western grades.

 

[George Harris]

....The wire will be higher above the rail than in the Northeast, as there is the need to be able to run double stacks under it, at least south of San Jose, and possibly high clearance for freight for most of the distance north of there.

The proposed Caltrain nominal contact wire height above top of rail, 22 feet, is exactly the same as the original PRR design in the NEC and the existing Amtrak clearance. The difference would be the absence of contraints to the nominal clearance. In the NEC the contact wire height is as low as 15' 8" inside the tunnels. Caltrain would not have any limiting areas like that.

Caltrain does have four tunnels, all between mileposts 1 and 5 and all apparently clearance problems. They are tight enough that you definitely feel the pressure pulse in your ears. There is talk of the wire being at 17'-0" through these tunnels, and also that this may not be practical to get it that high. There is freight through tunnels 3 and 4. South of the tunnels, though it will be 22' plus.

Speeds: Just out of the 4th and King station the curve is limited to 25 mph, after that the speed goes to 40 mph for a distance, then to 70 mph to a point somewhere south of the last tunnel. Other than about one more curve and a 40 mph section just north of San Jose and then 15?? mph in San Jose station, the rest of the portion north of San Jose is good for 79 mph. After a couple of slow miles right around San Jose in the UP owned part, most of the rest of the distance to Gilroy is also 79 mph territory.

 

[jis]

Your right Joel a single AEM7ac or HHP-8 would have a hard time with 8 cars in mountenous terain, compared to NEC.A single engine could never put the ponies to the rail so to speak, it would be sitting there spinning its wheels.

I don't know.... a single ALP-46 seems to have very little problem dragging 9 or 10 of those multi-level cars (which are known to be rather heavy, and way heavier than Amfleets) up the ramp from Millburn to Summit even under pretty bad conditions. Well at least they are not spinning their wheels sitting at a single place, so I suspect that Dutch, you are overstating your case a bit, unless of course ALP-46's are so spectacularly better than AEM-7s and HHP-8s.

 

[AlanB]

Your right Joel a single AEM7ac or HHP-8 would have a hard time with 8 cars in mountenous terain, compared to NEC.A single engine could never put the ponies to the rail so to speak, it would be sitting there spinning its wheels.

I don't know.... a single ALP-46 seems to have very little problem dragging 9 or 10 of those multi-level cars (which are known to be rather heavy, and way heavier than Amfleets) up the ramp from Millburn to Summit even under pretty bad conditions. Well at least they are not spinning their wheels sitting at a single place, so I suspect that Dutch, you are overstating your case a bit, unless of course ALP-46's are so spectacularly better than AEM-7s and HHP-8s.

Maybe the ALP-46 was engineered to climb it's namesake, the Alps. :lol: :lol: :lol:

 

[Dutchrailnut]

Your right Joel a single AEM7ac or HHP-8 would have a hard time with 8 cars in mountenous terain, compared to NEC.A single engine could never put the ponies to the rail so to speak, it would be sitting there spinning its wheels.

I don't know.... a single ALP-46 seems to have very little problem dragging 9 or 10 of those multi-level cars (which are known to be rather heavy, and way heavier than Amfleets) up the ramp from Millburn to Summit even under pretty bad conditions. Well at least they are not spinning their wheels sitting at a single place, so I suspect that Dutch, you are overstating your case a bit, unless of course ALP-46's are so spectacularly better than AEM-7s and HHP-8s.

The technology on the NJT ALP-46 is 10 years newer than the HHP-8 and AEM-7ac and 30 years newer than the AEM-7.

so again not much comparison.

And yes the hills in New Jersey or anywhere Commuter trains run can not be compared to western grades some as long as 20 miles.