They use two locomotives on the Chicago to Milwaukee trains when they are unsure of the reliability of the other locomotive. Such is the case with the new Siemens Charger locomotives, they have no clue how they will perform in harsh winter conditions so on the Chicago to Milwaukee runs they have been assigning two operating locomotives during harsh weather and running the cabbage cabs during moderate weather.
December 30th the Milwaukee to Chicago run I rode had a Cabbage Cab, Amtrak GE Frieght Style unit, and the Siemens Charger loco. It was minus 5 to minus 10 which is a Temperature unique to CONUS vs. Europe. Hence the caution on the new Siemens design. I expect once the Siemens Chargers experience a few winters they will trust them to run solo in harsh conditions.
I used to work long ago at the GM HQ building on West Grand Blvd with excellent views of the GT and Detroit trackage. They have several handy wyes in Detroit area and Northern Burbs such that the Chicago to Detroit trains can be easily turned at several points from near Detroit’s Amtrak station onwards…North. I am not entirely sure of Pontiac but there is another Wye somewhere up the line North of Detroit. Also remember from the old Bluewater Michigan trips the GT had a proliferation of WYE trackage in eastern Michigan.
The existence of these wyes doesn’t necessarily mean that they can be used easily. The wyes may be beyond yard limits which would translate into paying for a road crew to turn the train.
I had wondered about this too, on MO River Runner or IL service, there is never a rear engine, train is short. But they do have to carry some extra cars now in MO, UP wants extra axles, something to do with crossings so the train is longer, but not a push pull operation.
Back in the day, my carrier restricted single locomotives or single Budd car trains to 30 MPH. The limited number of axles did not guarantee the proper operation of the signal system at the time (relay based signals). The single moving piece of equipment could go through ‘detector’ circuits faster than the relays could detect the equipments presence and do their job properly.
I don’t know how big the Missouri River Runner’s are, no do I know what types of issues UP is seeing with their operation.
CSX still maintains the 30 MPH restriction on the operation of a single locomotive.
Two locomotives, or one locomotive pulling one car - 50 mph
Anything more than that is allowed track speed. These rules were introduced in years past after Dispatchers began noticing that small consists (caboose hops, single RDCs etc) would intermittently disappear from their CTC display panel.
The most recent instance of this becoming an issue was when VIA Rail was testing a 3 car Danish ABB Flexliner in Ontario and Quebec, operating it at the permitted track speeds of over 90 mph. Being articulated, the Flexliner had only 8 axles and did not properly activate track circuits or crossing warning devices at the higher speeds.
This is interesting because the fastest I ever saw an early Geep run was on the Northeast Corridor, just west/south of the Trenton bridge, in 2001: light engine and, to my eyes, considerably faster than 85mph (I was extremely surprised that the engine could run that fast, let alone be sanctioned to run that fast – I suspect some shop personnel had ‘breathed’ on it a bit). This was one of the Amtrak ‘orange’ units; perhaps someone knows what modifications these may have had.
Is there some aspect of ACSES or other systems that make signaling more reliable for light engines on the high-speed parts of the NEC?