The future of SEPTA's Push Pulls and EMUs.

Given some of the recent insinuations made against Push Pulls in another thread, as well as another thread which prodded us to develop an opinion of their utilization, I felt we might benefit from a single thread related both to the current utilization of SEPTA's existing Push Pull fleet, as well as a discussion of what future courses of action SEPTA may consider taking in developing it's EMU/Push Pull mix.

I'm somewhat curious as to what people's feelings are on the subject of an EMU/P-P split. SEPTA currently has a very low percentage of P-Ps , while NJT is opting for a nearly 50/50 mix, some would say to the detriment of their on-time rating. EMUs may accelerate fast, but under current FRA regs it seems they're doomed to be high-maitenance, high-cost shed queens who are required to spend an inordinate amount of time in the shops down for FRA inspections. Push-pulls may be slower, but the rolling stock can be utilized in a more efficient manner over the long run, the FRA mandated inspection only knocking the locomotive out of service for any extended time. Even in Europe where EMU-related regulations are far more flexible than the FRA's they run a mixture of Push-Pulls and EMUs, with most express trains seeing the former and locals getting the latter.

Just as an informal poll, would you rather see SEPTA drop it's push-pulls, do nothing, or get more?

Just IMHO, but I'd say that SEPTA could likely use some more push-pull sets. Some ALP46s and Comet V cars would fit well, and they'd allow SEPTA to cover runs like an R2 express to Wilmington (provided DE state ponies up some money), perhaps an R6 express to Norristown, as well as run another train or two of Expresses on the current lines that see them, perhaps taking Silverliners off those runs to do local service.

I'm all for additional push-pulls. The savings from not having to inspect the whole train every time is the clincher for me (plus, they have that "classic" train look ). I also think they'd to well on the Norristown line as an express, as there's a fair amount of space between the stations until Norristown, and that can be a long ride in the evenings on the local after a tiring day. They'd also be great for running expresses to Reading, or Quakertown, if someday SEPTA should perchance run trains out there again...
-JZ

PARailWiz wrote:I'm all for additional push-pulls... plus, they have that "classic" train look. -JZ

http://community.webshots.com/photo/853 ... 3573UZvVRY

Would be nice if they were used more often, especially on the Trenton, West Trenton & Paoli lines outside of peak times. But I guess we have a hard time filling trains during those periods (except for the Trenton Line).

JZ: It's funny you should mention that push-pulls look classic, since historically, as each line on the Pennsy and Reading was electrified, they converted to MU operation. The PRR even had the foresight, in 1910, to design their Class P54 all-steel coaches to be easily converted to electric propulsion. The electrification of the Paoli line was operational in 1915, for the purpose of increasing capacity along the line and at Broad Street Station due to their better acceleration and speed over locomotive-hauled coaches, which at the time meant steam locomotives.

The maintenance issue is a fairly minor point, and historically, MUs had the advantage over locomotives. The initial preference for MUs was because they could be inspected and turned around faster than steam locomotives. Now, with electric locomotives, you will need to compare the actual costs for buying and running a loco+coaches versus MUs. With my "back of the envelope" estimates, MUs are more efficient with 4 or fewer cars, electric locomotives are more efficeint with more than 6 cars, and at 5-6 cars, it's about even.

(Source: Electric Traction on the Pennsylvania Railroad 1895-1968 by Michael Bezilla. Penn State University Press: 1979)

JZ: It's funny you should mention that push-pulls look classic, since historically, as each line on the Pennsy and Reading was electrified, they converted to MU operation.

When I said more classic, I meant relative to the traditional idea of trains, and really only in pull mode. You don't see many MUs (E or D) on model train sets, for instance (although my favorite model car is my Reading Co RDC, but I digress). And don't forget the GG1, possibly the most impressive of the PRR's electric equipment.

With my "back of the envelope" estimates, MUs are more efficient with 4 or fewer cars, electric locomotives are more efficeint with more than 6 cars, and at 5-6 cars, it's about even.

The answer here seems pretty simple, then. Have enough push-pulls so the six+ car peak and express runs can be run with them, and use the EMUs for the smaller local and off-peak trains.

That being said PAR, why is SEPTA looking to purchase more MU's? Clearly their capacity shortfall occurs during peak hours. Even with the retirement of the SII's and III's, there should be no off-peak shortage. So why not order more PP's?

A good litmus test would be to ask how many peak hour trains are currently run with MU's that are 4+ cars? They are the ones that would be good candidates for PP conversion. I notice the Doylestown express that runs express to Ft. Washington is currently MU yet 6 cars long. Why doesen't that get a PP but the R2 Warminster which makes more stops does get a PP?

jfrey40535 wrote:I notice the Doylestown express that runs express to Ft. Washington is currently MU yet 6 cars long. Why doesen't that get a PP but the R2 Warminster which makes more stops does get a PP?

I suspect it's because the power supply of the Doylestown Branch couldn't handle an AEM-7. MU trains are restricted to the P2 notch because of the inadequate power supply, IIRC.

What about running the express just to Lansdale? I'm not sure what a P2 notch is, but I take it has to do with how fast the train can accelerate and how much power the train can draw.

If that's the case, why isn't SEPTA spending money to upgrade the power systems instead of fancy high-level platform projects and nonsense like that?

Does a single AEM-7 draw more power than a 6 car MU train? I guess if a single locomotive is handling all of the acceleration then the answer would be yes.

The Metroliners were rated at 1000 HP per car and although I can't find any exact specs, I believe I read somewhere that the the MU's are around 600 HP per car while an AEM-7 is rated at 7000 HP. If those specs are accurate, a 6 car MU train would draw a little better than half the power of a similar PP at full power.

P2 limits the car to the A+B windings. This gives an effective top speed of 60mph, and full acceleration to full A+B winding voltage. HP is 4 motors at 156HP, or 624HP or an SL II/III.

I don't think P2 limits acceleration (Switching does), but the motors won't develop full power at speed because they're operating at 2/3rds full voltage, max.

I don't have an HP for the Metroliners - annoyingly, GE's service book doesn't list it.

An AEM-7 is NOT 7000 HP, actually. They're really 5800 or so HP, or 4320 kW. That's traction motor input, actual at pantograph wattage is slightly higher, thanks to HEP, losses, etc. This from GM's manual on them.

Substation supply being limited might be it - if a line was a lightly or less used branch (I don't know about the one in question), it would likely get a smaller than usual substation, on account of lower speeds and fewer trains. Or, at some point in history, a substation might have popped and they did a quick fix to keep the line going.

Why not replace it? Does Septa have any plans on going to 60hz or 25kv power? In that case, it'd be worth waiting for the SL Vs and getting rid of the II/III cars (Which are less 60hz and 25kv compatible than the SL IVs, som e of which have changeover gear already), then just bumping the line up to 25kv 60Hz. 25Hz power equipment isn't cheap and isn't readilly available. Waiting a few years for a 25kv 60hz changeover equipped fleet, and then redoing the power system might be a better idea.

On the original topic of Push-Pull vs EMU:

Pros for EMU:

1. Better acceleration
2. Lower weight for trains of 8 cars or less
3. More operational flexibility in making up trains

Cons for EMU:

4. Higher initial cost (6-car MU is about $18 million, while a 6-car push-pull is about $10.4 million)
5. Higher maintenance costs and time since each MU is a locomotive
6. The longer the train, the bigger the cost disadvantage of EMU trains


1. Better acceleration: Because there are more driven axles, an MU can accelerate faster than a locomotive-hauled train. Better acceleration means trains lose less time at station stops, and with SEPTA's closely-spaced stations, you can gain several minutes with better acceleration (end-to-end on locals).

2. Lower weight for trains of 8 cars or less: This translates into less power usage and less wear on the tracks, saving operating costs.

3. More operational flexibility in making up trains: With an MU, you can easily add or drop cars to adjust for ridership. With a push-pull, you have to add/remove trailer cars between the cab car and locomotive to change their length.

4. Higher initial cost: Using NJT's figures from 2002, I adjusted for inflation to 2003 dollars, and an ALP-46 locomotive is about $4.775 million, a Comet V trailer is $911,000, and a Comet V cab is $1,067,000. Silverliner V cars cost about $3 million each. For the same amount of money, you can buy a lot more push-pulls.

5. Higher maintenance costs and time since each MU is a locomotive: I think this was already covered in the original post.

6. The longer the train, the bigger the cost disadvantage of EMU trains: Conversely, the shorter the train, the better for MU operation, especially when you have 2 or 3 car trains. This depends on how much ridership grows over the next few years. The limited ridership data I have (for Delaware Co.) shows ridership dipped in 2001 and 2002, but improved in 2003.

I think on the R6 Norristown line, some stations such as Ivy Ridge have platforms only about 100 feet long, which means they can only platform three cars. The longest train I've seen on that line when I used to take it in the mid-1990's was four cars.

I think the prerequisite for a push-pull is an express train making few stops with enough ridership to run 6-car trains. If there are enough of these for a 7-10 trainset order of push-pulls, I think they should go for it.

I think on the R6 Norristown line, some stations such as Ivy Ridge have platforms only about 100 feet long, which means they can only platform three cars. The longest train I've seen on that line when I used to take it in the mid-1990's was four cars.

Just to clarify, the 7:34AM train into Philadelphia when I was riding it regularly in June was 6 cars long, and before they reinstated the "Schuylkill Valley Flyer," the train at 5:00 was also 6 cars long.

Maybe this belongs more in the SEPTA cost-saving ideas forum, but... I was in Trenton on Sunday and noticed SEPTA's push-pull consist laying over for the weekend. What struck me was that the pan was up, and the whole consist was humming like it was ready to roll. What gives? How much juice does a toaster suck down over the weekend sitting in "idle"? (I know, electric locomotives don't really idle, but you get the point.) And why on earth would you need to power an AEM-7 and 5 empty coaches' lights and ventilation for 48 hours on a warm fall weekend?? When I lived in Germany there were local push-pull sets that shuttled between Kiel, where I was, and Hamburg, an hour and 15m to the south. The consist would pull in to the station (great old place, 6 stub-end tracks and a trainshed) and before everyone was even off the train the crew dropped the pantograph. And their layover in Kiel was probably 2hrs, tops. 5 minutes before departure, they would raise the pan, the engine came to life, and then it was off to the races. If SEPTA is serious about saving money and plugging the deficit, I know one place they can trim their electric bill.

Good point. There's nothing that can freeze on an electric. The Silverliners need a warm up (1 hour or so) below 50 degrees, or at least did, but the AEM-7 doesn't, and it takes no time to hit the "Pan down" button and shut everything. And the book says basically all you do is hit the button, set the parking brake, open the battery switch.

And when the pan's down, power consumption = 0

With the pan up, the main breaker can still be open, and no power's being used. With the main breaker closed, a number of equipment blowers run, plus the HEP system to run the compressor. If unused for 15 minutes or so, the HEP system kicks down a bit. I don't know what an AEM-7 draws at rest not supplying HEP, but it's probbably a few kW - when powered, the transformer MUST be cooled, or it'll overheat (bad).

Silverliners use less power, especially if the MA sets are off. But they too have transformer cooling pumps and blowers that need to run. The IVs also have anode heaters on the ignitron rectifiers, if those tubes are still used in those cars. The SL II/IIIs didn't have these, and need a 1 hour warm up before power operation (if THEY still use ignitrons). This is to ensure that there's no mercury condensation on the anodes of the two ignitron tubes in the propulsion system. If there is, and power's taken, it can severely damage the tube. Septa might have converted these cars to SCRs, as MN did with their M-2 cars. As delivered, they used ignitrons and thus required some care in powering up. I don't know if the propulsion system on these cars is still like this on the SLs.

Anyway, even still, there's zero reason to leave the pan up over the weekend. Especially given it takes about 2 minutes to drop and secure everything.