look at it in a different way
Put a real railroad spin on this question. I hope this dosen't sound to "overwhelming". After all, it's just a model railroad, isn't it?
Here is another way to look at blocking (switching out) your train. Make yourself the conductor of that train. Ask yourself the following question: What's easier for me (and the engineer) to do? Of course, you want all of your cars blocked together. You don't want to arrive at an industry or interchange with those cars for that destination scattered throughout your train. How soon do you want to be done? You basically want a "easy in, easy out" scenerio each time you stop to do work. It's like a game or a puzzle. There is no right or wrong answer. You can give 10 conductors the same switchlist, and you will get 10 different answers on how to do it. The goal here, as on the real railroads, is what is the most efficient way to get it done.
After you leave the yard and arrive at your first destination or industry, the "engineer" does not want to keep going back and forth from the main to the siding while you switch out your cars. And the "dispatcher" dosen't want you holding up the track any longer either. Your train should be blocked BEFORE starting your trip. All the work should be done in the yard first. Why? Because in the yard, you have more time to work. You are not holding up any trains on the main and you have access to multiple tracks to sort your train. That's makes a huge difference because you can block cars for different destinations on different tracks. When your done, all you need to do is grab the different tracks, in order of the way your work is to be done, and leave. Most likely, you don't have that option after you leave the yard.
From a real railroads ponit of view, keep these tips in mind:
What industries (or interchanges) need to be serviced today and in which order are they going to be done as you progress down the line.....err....around the layout. This is how your cars should be blocked in your train BEFORE you depart. 1st come, 1st serve.
What runarounds, sidings or wye's need to be utilized to get the work done and how many cars will those sidigs hold. This is important if you have facing point switches. How are you going to service that industry and "get around" the cars for that industry. Maybe you can just save that move for your return trip when it becomes a trailing point switch. HMMMM it's kind of like a game.
If you are picking up outbound cars (empty or loaded cars pulled from customer sidings or interchanges), where do you want those placed in your train. In other words, are you going to be picking up these outbounds on the head end, behind your engine(s), or off the rear end, behind your consist and ahead of the caboose (if you have one). That makes a big deal to the engineer. As you progress down the line, and you are picking up cars off the head end, the engineer will have more cars to handle (hang on to) going into and out of sidings. More cars equals more slack for that engineer to control. You don't want the engineer hanging on to, say, 20 cars to spot a car on a siding that holds only 1 car. The slack in those 20 cars alone, if not adjusted properly by the engineer, could force that car right off the end of the track.
I know of a engineer up here on the NYS&W RR that always had to have empties on the rear of his train heading back to Utica, NY. Why? His reason was simple. On the Northern Division of the NYS&W, there is a really steep grade northbound, from Paris, NY to Utica, NY. He said that by having empties on the rear of the train, they acted as "parachutes" when the brakes where applied. Whereas having loads on the rear "pushed" the train downhill. The empties on the rear end would tend to "pull" the train backwards and help hold the train back by keeping it "stretched out" going down hill. Makes sense to me.
Certain industries may request cars to be placed in a certain order, for unloading purposes, on their siding. Do this before you leave the yard as well.
Next time your trackside, LOOK at the train itself as it passes. I know, most people want to see which engines are in the lead. But after the engines pass, look at the train. In what kind of order are those cars in. What kind of cars are blocked together? Where are the empties located? Why are they in THAT order.
Get the big picture before departure. What cars need to be on what tracks, what sidings and where on those sidings? What customers need to be serviced first or last? Are the cars properly blocked according to destination, interchange or work to be done. Are your Hazardous Materials tank cars properly spaced? Sorry, I just had to throw that one in. I did'nt know how "in depth" you wanted to get. Federal regulations require loaded HazMat cars be "buried" at least 6 car lengths from an occupied engine or caboose. Empty HazMat cars need to be spaced 2 car lengths from a occupied engine or caboose. Are yours?
What do you want your train to look like when the work is done? Where do you want the outbounds located?
To me, yard operations are the best part of model railroading. Yes, I enjoy watching trains run around the layout and, in real life, rolling down the mainline. But so much work is done behind the scenes that people often forget about. Those trains were "made up" somewhere along the line and chances are that a "yard crew" put it together. Don't be in a "rush" to get out on the main. Get your train properly blocked before leaving the yard. It will save you time and aggrevation down the line.
Sorry if this got too much in detail for you. It's just the railroader in me that sometimes has to come out of retirement.
