Informative thread. Thanks for the invite, Jay Pat.

I can remember as a youngster looking through a table from the Grand Trunk Western, listing the different lines with tonnage limits and motive power requirement. It had types of cars, loaded or empty, number of cars and a list of locomotives appropriate for the line. I think grades, curves, and weight of the rail were all factors.

Even into the 50s the GTW still ran mixed trains on a few routes, and mostly steam power, and the schedules were pretty loose. It could be an all day trip behind a light pacific between Pontiac and Caseville (Michigan) for example - about 100 miles.

Here are some great photos and stories about the last days of steam on the GTW from Richard Leonard:

https://www.railarchive.net/rlsteam/gtw.htm

https://www.railarchive.net/cnrgtwdvl/index.html

Mike

I’ll do my best to answer & fill in the blanks. The length of trains in this country is determined by the physics of the routes - grades & curves that are encountered. Also, where the freight is headed. The couplers can only stand so much stress. A 100 car train with no engines in the middle or end can exert 15 tons at the head end couplers. Pulling a whole coupler assembly out of a car is not uncommon. Breaking a knuckle on a coupler is so common that locos carry extra.
The railroad term for power spread throughout the consist is DPU (Distributed Power Unit). The advantage of diesel electrics from late 1930 was that one engineer could control multiple units at the head end. This was done with a four conductor wire between the units. Todays DPU’s are controlled by radio frequency from the head end. All the units must be newer computer controlled locos capable of exactly mirroring the engineer inputs at the head end.
DPU advantages are two fold. 1. Breaking - At consist starting out is able to charge the train 60% faster and break response is 30% faster. As for breaking pressure - air is air - so long as there is 90 lbs in the system the breaks will be applied even if there are no DPU’s. 2. DPU’s greatly reduce coupler strain and starting slap (take up). Locos make extensive use of dynamic breaking which greatly decreases ware on physical air breaks and pads. The engineer reduces the throttle to idle the engages dynamic breaking which turns the traction motors into generators providing resistance to the wheels. The current created is send to a diode bridge which creates heat and dispensed through large fans. This works til about 10 mph when the air breaks are engaged to stop the train. This a very useful in controlling train speed on steep down grades, using breaks when required and preventing over heated breaks.
Newer locos from about the mid 1980’s onward make extensive use of computers and sensors to monitor and control engine and traction motor functions. Gone are the days when an engineer could rough handle the throttle or overload the generator and /or the traction motors. Getting the weight moving is now pretty much controlled by computers. Sensors on the traction motors (axles) can detect potential wheel slip and signal air pressure to shift more engine weight to that axle(s).

Interesting fact: The record for the longest train goes to Australia. A mining company ran 483 full ore cars from the mine to the smelter with 3 head end locos and 5 DPU’s. It was on the the flat outback with no sharp curves.

Yes, I do count them, but something has been bothering me lately about the trains and I am wondering if anyone else has noticed this.

I have lived near enough to be within earshot of trains all my life, all over the country - I grew up on The Main Line. I have always listened the horn signals as the train approaches the various crossings. I now live in Florida and sometime about two years ago, I noticed that the Engineers - the train drivers - stopped deploying the signal correctly. The international signal protocol for a train approaching a crossing is stated and unambiguous: The engineer must begin the signal at 1320 feet from the crossing; 2 Long, 1 Short, 1 Long; the entire sequence must be not less than 15 seconds nor longer than 20 seconds. This allows a 3 second space between signals with the longs being 3 and theshort 1 second. Now I hear some engineers go through the entire sequence in as little as five seconds. then they realize they are still nowhere near the crossing and have to do it again. Idiots. They must have Millenials driving the trains now.
Has anyone else noticed this in other parts of the country?

Yes, I do count them, but something has been bothering me lately about the trains and I am wondering if anyone else has noticed this.

I have lived near enough to be within earshot of trains all my life, all over the country - I grew up on The Main Line. I have always listened the horn signals as the train approaches the various crossings. I now live in Florida and sometime about two years ago, I noticed that the Engineers - the train drivers - stopped deploying the signal correctly. The international signal protocol for a train approaching a crossing is stated and unambiguous: The engineer must begin the signal at 1320 feet from the crossing; 2 Long, 1 Short, 1 Long; the entire sequence must be not less than 15 seconds nor longer than 20 seconds. This allows a 3 second space between signals with the longs being 3 and theshort 1 second. Now I hear some engineers go through the entire sequence in as little as five seconds. then they realize they are still nowhere near the crossing and have to do it again. Idiots. They must have Millenials driving the trains now.
Has anyone else noticed this in other parts of the country?