View Full Version : Norfolk Southern - Where are the AC units?

09-14-2003, 09:25 PM
Why doesn't Norfolk Southern go with AC powered units? BNSF has their SD70MAC's, UP has their CW44AC's and so does CSX, so why not NS? Is it a money issue or something else? To the best of my knowledge, the only AC units they have are 17 ex. Conrail SD80MAC's but they use them in helper service! I know that NS hauls alot of coal and on most coal trains they usually need 3 DC powered units. Two AC powered units could easily replace 3 DC powered units. Plus, AC tractions motors last longer and can tolerate more strain at low speeds. Wouldn't it be more cost effective in the long run if they went with AC units?

09-15-2003, 04:57 AM
I seem to recall hearing somewhere that it was more of a logistics issue of having to keep only DC loco parts. Does anyone know if this is right? I would also guess it is a matter of preference. A point to make also is that Union Pacific is heavy into DC power with the bulk of their new units being SD70M's. Still the pulling power of the newest locos AC or DC is much better than say 15 years ago when consists of 4-6 SD40-2, SD50, C36-7, and C30-7's was very much the norm in coal country.

Hope this helps

09-16-2003, 04:30 PM
All that you say about AC units is true, but it all comes down to economics, which can vary from road to road. NS has a "one size fits all" philosophy in that they want locomotives to be equally suited for all types of service. They feel that the utilization benefit from being able to use any locomotive on any train outweighs the benefit from sometimes needing one less locomotive on a coal drag. A 4000 HP, ~110,000 lb TE, DC locomotive fits this description given NS's trains and routes.

About 1/2 the benefit from an AC unit comes from the extra tonnage it can handle in drag service. The other 1/2 is reduced maint costs. Neither alone will justify the extra bucks an AC unit costs, so you have to be able to keep it in service where you can reduce the number of locomotives. If you can only do this some of the time, it's cheaper to go with DC. BNSF and UP can concentrate the AC units on Power River trains in dedicated service, so AC makes sense for them there. NS might be able to do the same thing with Poky and PA coal, it's really not the same animal as Powder River.

Now, a good question might be "Why does CSX have any AC units?" They seem to use them interchangably for and with DC units. They also seem to have a whole mess of "junk" leased power on the property on a continuing basis which suggests to me that their fleet and fleet planning are out of control.


09-17-2003, 02:40 AM
I have to agree with Don in regard to CSX's apparent lack of motive power planning. My in-laws live in Hamler, OH on the old B&O mainline. I am always astounded to see AC6000CW's singlehandedly hauling intermodal trains -- an application that the NS on the Illinois Division handles many times with a single DC Dash9. According to all the basic "laws" of motive power planning, high speed intermodal runs are the one of the least cost effective ways of deploying AC locomotives. I also, like Don, have seen many AC units mixed in with DC units on CSX.

Powder River Basin coal trains appear to have been the best application for the units, but at last count BNSF and UP are buying many more DC units than AC units. At the current time the AC market appears to be reaching the saturation point. GE and, particularly EMD (with its new SD70ACe), appear to be looking for ways to get the AC locomotive finally adopted as the "standard" for all types of service. Railroads like NS and CN will certainly make achieving that goal difficult, at least in the short term. If AC is the most cost effective form of motive power, one must ask how CN has managed to achieve the lowest operating ratio of all the major systems?