Locomotive cut-in about 2/3 down consist?

I live in Rochester, NY, near the old NYC water-level route, which all in all is pretty flat all the way from the Mohawk Valley to Chicago. Yesterday, while waiting for my car at the repair shop, I was watching on the mainline, when an intermodal came past. First thing I thought was odd was the fact that there was only a single AC locomotive at the head whereas I've only ever seen 2 or more. It was a full-length train (easily 100 cars), but there was a second locomotive cut-in about 2/3 of the way down. Now, I know such things are common in mountainous terrain, but I have NEVER seen such a thing on the old NYC main. Is this something CSX is doing now, and for what reason? Could it be that they plan to break-off the 2nd locomotive and all the cars behind it somewhere between Rochester and Chicago?

That train was set up for Distributed Power,lead unit controls that "cut in" unit by remote radio control.
Tends to allow better train control on grades

This is something CSX has been doing for at least a year in these parts. As they started making longer trains they were having problems getting from A to B, conversations with the dispatcher were ending with 'good luck' before the crew left the yard, that's about when I started noticing the DPU's.

Been nothing the same thing east of Springfield on the B&A. Some of the trains have had units on the rear of the train as well.

Way back when UP started getting into distributed power in a big way, someone started propagating the myth that all DP trains are more fuel efficient. A radical decision was made by Western Region leadership at that time to have a policy of putting DPUs on all trains when possible, even those that were only moderately heavy and/or lengthy. This decision added a good bit to terminal dwell time, since it takes some extra time to set up DP trains for departure, as well as to yard them on the other end of the trip.

Reality is that DP operation saves fuel only when the end result is to move more tonnage with less power (fewer units). However, there are also situations where asynchonous throttle/dynamic brake modulation can introduce greater efficiency -- but to do this effectively requires extra skill and attention on the part of the operator.

I'm not informed about this aspect of CSX operation, but I wonder if they are sorting out different options and their operational consequences.

Last October I shot some photos along the river line, saw no trains with DPUs - Friday morning I was three. Two DPUs halfway through the train, and one on the rear. I'm guessing this is the new norm on the river line too.

I occasionally see CSX running trains with DPU on Metra/Rock Island tracks, on their way to or from the New Rock Subdivision. Normally, though, the extra unit is at the very rear of the train. Sometimes, there will be a Geep idling away at the back instead of a DPU, for switching purposes, replacing the cabooses they used on the New Rock for quite a long time after they disappeared elsewhere.

Whenever I've seen IAIS use distributed power (they use Metra and CSX to get to their own rails), it has always been one unit in the lead and one at the rear.

Saw another train last night through Rochester, all stacked containers, with 2 units spliced in, and it seemed to be longer than the usual ~100 car consists, too. what is the maximum length on a train through this area now?

D Alex wrote: ↑Sun Oct 06, 2019 9:02 am Saw another train last night through Rochester, all stacked containers, with 2 units spliced in, and it seemed to be longer than the usual ~100 car consists, too. what is the maximum length on a train through this area now?

I believe it is 15K feet on the Water Level Route.

'Part of the less but longer trains involved in "precision railroading."

Noticed a long mixed freight running down the RF&P with a double DPU in the middle of the consist the other day. Both engines were powered on.

Is this becoming a common practice for CSX?

KTHW wrote: ↑Tue Apr 20, 2021 8:27 pm Noticed a long mixed freight running down the RF&P with a double DPU in the middle of the consist the other day. Both engines were powered on.

Is this becoming a common practice for CSX?

While CSX was late in adopting the use of Distributed Power (mostly because of communications issues through their mountainous territories) they have now fully embraced the use of DPU - and they did upgrade their communications abilities in the mountains.