MikeLowaryI am a brand new forum poster although I have been a member a few years. Today while housebound with the crazy -25 windchill here in NW Illinois I was watching activity at Rochelle online and spotted an EB UP mixed fright being pulled by 10!locomotives at 250 pm. I've never seen that many locomotives in a set before. I'll post a pic when admin allows me to. First of ALL: Mike! The 'move' you observed with multiple locomotives, would generally be a move to redistribute the locomotives back into an area where the 'Power Desk' controling that operational area would antisipate a 'need'. Here in South Central Kansas, we'll see those moves of power with a higher frequency than many other areas ( Eastern end of the Southern T-con of BNSF). Several over time, I've seen, were as many as thirteen locomotives on one train. Some of those engines were D.I.T. (Dead in Tow). Generally, Eastbound trains will have 4 to 5 units on the head end. Westbounds seem more likely to use DP on the rear;with 3 or 4 units on the head-end. A couple of times a week we'll see an 'Export' Stacker, with a couple of DP's in the train, and one DP unit pushing. The Stack Trains with 'Domestic Cans' ( primarily, JBH) will always seem to have ample power for their loads. Cannot speak much about UP's trains in this area (Mostly, North/ South on the OKT sub: nee R.I.) Seem to be mostly grain/Hopper trains/UPRR has a small yard & service facility in North Wichita; (and then travels NE towards KCK area from Wichita) UPRR does seem to run some trackage rights moves from the Arkansas City Area through Wichita, not sure how frequently that happens(?)
First of ALL: Mike!
The 'move' you observed with multiple locomotives, would generally be a move to redistribute the locomotives back into an area where the 'Power Desk' controling that operational area would antisipate a 'need'.
Here in South Central Kansas, we'll see those moves of power with a higher frequency than many other areas ( Eastern end of the Southern T-con of BNSF). Several over time, I've seen, were as many as thirteen locomotives on one train. Some of those engines were D.I.T. (Dead in Tow).
Generally, Eastbound trains will have 4 to 5 units on the head end. Westbounds seem more likely to use DP on the rear;with 3 or 4 units on the head-end.
A couple of times a week we'll see an 'Export' Stacker, with a couple of DP's in the train, and one DP unit pushing. The Stack Trains with 'Domestic Cans' ( primarily, JBH) will always seem to have ample power for their loads.
Cannot speak much about UP's trains in this area (Mostly, North/ South on the OKT sub: nee R.I.) Seem to be mostly grain/Hopper trains/UPRR has a small yard & service facility in North Wichita; (and then travels NE towards KCK area from Wichita) UPRR does seem to run some trackage rights moves from the Arkansas City Area through Wichita, not sure how frequently that happens(?)
There are usually rules about how many equivalent powered axles can be on line. Others can provide specifics (and have in the past).
As noted, that many locomotives indicates a power move, with the excess power dead-in-tow. Given the cold weather, those locomotives may be running, but are isolated and the brakes are "boxcarred," ie, set up to act just like any other car in the train.
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tree68There are usually rules about how many equivalent powered axles can be on line. Others can provide specifics (and have in the past). As noted, that many locomotives indicates a power move, with the excess power dead-in-tow. Given the cold weather, those locomotives may be running, but are isolated and the brakes are "boxcarred," ie, set up to act just like any other car in the train.
CSX Rules when I retired permitted 24 powered axles on the head end and 12 powered axles on manned rear end helpers.
An AC locomotive counted as 9 axles and the DC locomotives counted as 6 (presuming they were actually 6 axle locomotives).
There are also rules pertaining to how many axles may be used in Dynamic Braking.
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UP just changed how many engines can be in a train's locomotive consist from 8 to 10. That doesn't mean all 10 can be used for power. When you see that many engines at the front of a train, you can be sure that most aren't on-line, that is producing power. With the temperatures below 35 (way below 35 currently) servicable engines may be running but isolated. Those not servicable will be dead and drained. Off and on, they've been moving dead power, some of which I heard may have been sold off.
UP assigns power according to Tons per equivalent Powered Axle (TPA). Engines have an Equivalent Powered Axle rating. An equivalent axle is locomotive's tractive effort compared to one standard axle which has 10000lbs of tractive effort. (There is also a dynamic brake axle rating but I'll limit this to powered axles.) The modern General Electric AC variants are rated at 12.1 axles, the EMD SD70ACe variants are rated at 12 axles and the SD70m (DC units) are rated at 10.1 axles. For UP, that's mostly what comprises road power across the exCNW. Not that you can't or won't see others in consists.
The original post didn't include whether the train had a DP. For this example, I'll figure it didn't. That would limit the train to 10000 ft from the end of the last engine in the consist. For this example we'll figure the train at 9500 ft (cars only) and weight (again cars only) at 9500 tons. (footage length to gross weight isn't exact, but often is pretty close. It depends on how many loads and how many empties. We seem to be moving a lot of empties right now, both ways.) TPA for most manifests across Illinois and most of Iowa is normally 500 TPA. So divide 9500 tons by 500 TPA equals a requirement for 19 EPA. That means two GEs or two EMDs (AC or DC) or a combination of both could handle the power requirements. But wait, engines not on line have their weight added to the train's weight for TPA purposes. So eight engines along for the ride at about 200 tons each, comes up to another 1600 tons. That makes total trailing tonnage now 11100 tons. Divide that by 500 now equals 22.2 axles required. Two GE or EMD AC types could handle it, but if the only working power was the SD70m type, you would need three on line to stay under TPA.
So I'd bet that the train in question should've had at most 3 engines on-line under normal circumstances. Currently, the bitter cold isn't normal. With the subzero temperatures, track bulletins have been issued that allow all running engines to be on-line up to the absolute EPA limits (lead consists of 62 EPA for intermodal, 52 EPA for everything else) to keep them from freezing up. So that could account for an extra engine or two that normally wouldn't be used.
One other thing about engine consists. On-line engines don't have to be next to each other. You could have them interspersed through a consist. If that train only had 3 out of 10 on-line, it wouldn't have to be first, second and third. It could be 1st, 3rd and 5th, etc.
Jeff
CN still assigns locomotives to trains based on horsepower per ton, and we have different ratings for AC and DC units. The AC units seem to be able to operate at 0.2 HPT less than DC units.
Our maximum consist rules are in powered axles, 24 DC axles or 18 AC for traction, and 18 DC or 12 AC for dynamic braking. Consists composed of both AC and DC units are governed by the AC rules. As our road fleet is almost entirely composed of 6-axle units the limits conveniently work out to 2, 3, or 4 units. There are also exemptions for certain routes where more power may be needed, and a Engine Service Officer (CN-ese for Road Foreman of Engines) may authorize one-time exemptions if a train requires additional power for some reason.
When operating a train with distributed power, the lead and remote locomotive(s) are considered as separate consists, and the rules apply to each individual consist. But a remote consist is not allowed to have more powered axles than the lead consist.
I am not aware of any limitations on the number of locomotives with the independent brakes cut in per consist, but when operating a 10 locomotive consist one must be very careful not to jackknife the train when using the independent brake.
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SD70DudeI am not aware of any limitations on the number of locomotives with the independent brakes cut in per consist, but when operating a 10 locomotive consist one must be very careful not to jackknife the train when using the independent brake.
Our rules allow up to the locomotive containing the 36th axle. I think it's the 36th axle. I don't run big consists anymore, so if I did, I'd have to check the book. But 36 sticks in my head.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
My concern wasn't with jackknifing the train (you always kept that in mind), but with moving the engines around in a safe manner.
The thing about independent brakes is that each time you add a unit to the consist, you add time for the brakes to apply as the pressure signal has to build up in the pipeline. One unit works great, three units takes a little longer, six units takes way too long, etc. This also applys to releasing the brake. The more units with the independent working, the longer it takes for the brakes to release.
Due to the time that it took for the brakes to apply & release, I tried to keep the number of axles down to no more than 20 (five four axle units), three six axle units (18) was the norm. Anything over that, I found to be asking for trouble (Even when switching, four units cut in were a bit of a hinderence).
If the said 10 unit consist were to have all of the independents cut in, the consist would be basically uncontrolable and a very good way to get by a red board when operated in a "Lite Unit" move.
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