09-22-2009, 10:55 AM
True "loads-in/empties-out" operation, in a modelling sense, usually refers to "paired" industries, such as a coal mine and a power plant. These would utilise the same sidings, but be separated by a backdrop or view block. A string of loaded hoppers would be pulled from the mine area, travel around the layout, as required, then be shoved into the power plant's siding (which is the same track from which it left the mine). In other words, the mine on the opposite end of the siding now has "another" loaded train, ready to go. The locomotive that was used to deliver the coal to the power plant can now pull a string of empties from the plant's other siding and return them to the mine's loading track, which is merely the opposite end of the siding from where they're leaving the power plant. This requires two sidings, connected through the backdrop to each participating industry. One siding at the mine is the "loads-out", while its opposite end at the power plant is the "loads-in" track. Similarly, the "empties-out" siding at the power plant is, at its opposite end, the "empties-in" track for the mine. For this scenario, you also need two trains of hoppers, one loaded and one empty. You could accomplish the same traffic movement with only one connected siding and one set of hoppers, but it would involve actually loading/unloading the hoppers between operating sessions, which means that you'd generate only one train movement (empties or loads) per session.
When the second level of my layout is built, it will incorporate a power plant (unmodelled, but represented by a staging track). Loaded coal trains will appear from an interchange (another staging track), travel around the layout, then end-up at the plant's track. The hoppers will be emptied (live loads) between operating sessions, and return to their point of origin at a later date. Since I'm usually a solo operator, this scenario will probably occupy an entire operating session, so I don't require the "empties-out" phase immediately, nor the additional siding. Coal train movements (and returning empties) are planned to be three times per week (using "layout time"
), but, depending on which trains I feel like running, the interchange track and the power plant's siding can be used for whatever other trains and industries I choose, as long as the hoppers have been physically removed from the layout. I don't have room to keep cycling the loads/empties back and forth. The next coal train of the week ("layout time" again 
) might not occur for many weeks (actual time).
In my opinion, staging is one of the most important keys to operation, whether it be a full staging yard, a cassette, or even a single siding. Staging can represent industries that you don't have room to actually model, and it can also represent the railroads with which your railroad connects (which also connect to even more industries).
Then, all of those cars that you just "gotta have" don't necessarily need to be appropriate for the industries which you actually model. They could be coming from "elsewhere", via a staging or interchange track, and going to a modelled industry on your layout, or coming from a modelled industry and going "elsewhere", or, they might be coming from "elsewhere" and going to a different "elsewhere", in other words, overhead traffic.
Most of us have limited space in which to build a layout, so it's unrealistic to expect to be able to effectively model more than a handful of industries. A single staging track takes up very little space (width-wise, at least) but can represent as many industries as you'd care to have, and can also represent your interchange point with "the rest of the world". My layout will have an interchange track (single dead-end siding) at both the north and south ends of the line, interchanging directly with two different railroads, plus a staging yard at both the northern and southern ends of the line. These will represent not only a connection with a third railroad (the same one, both north and south), but also a lot of unmodelled industries, many receiving multiple cars per session. And, because the industries are not modelled, I can use the same tracks to represent as many industries as I wish - not all at the same time, obviously, but from session to session. Similarly, I have two industrial staging sidings at the south end of the line. These represent an industrial switching district, again with none of the industries actually modelled. The industries there will ship and receive commodities via the modelled portion of the layout, generating traffic and allowing me to use many cars that wouldn't otherwise be seen.
As you can see, the industries that you don't model can be, even if not as interesting visually, as important operationally as those which you do.
Wayne
When the second level of my layout is built, it will incorporate a power plant (unmodelled, but represented by a staging track). Loaded coal trains will appear from an interchange (another staging track), travel around the layout, then end-up at the plant's track. The hoppers will be emptied (live loads) between operating sessions, and return to their point of origin at a later date. Since I'm usually a solo operator, this scenario will probably occupy an entire operating session, so I don't require the "empties-out" phase immediately, nor the additional siding. Coal train movements (and returning empties) are planned to be three times per week (using "layout time"
), but, depending on which trains I feel like running, the interchange track and the power plant's siding can be used for whatever other trains and industries I choose, as long as the hoppers have been physically removed from the layout. I don't have room to keep cycling the loads/empties back and forth. The next coal train of the week ("layout time" again ) might not occur for many weeks (actual time).In my opinion, staging is one of the most important keys to operation, whether it be a full staging yard, a cassette, or even a single siding. Staging can represent industries that you don't have room to actually model, and it can also represent the railroads with which your railroad connects (which also connect to even more industries).
Then, all of those cars that you just "gotta have" don't necessarily need to be appropriate for the industries which you actually model. They could be coming from "elsewhere", via a staging or interchange track, and going to a modelled industry on your layout, or coming from a modelled industry and going "elsewhere", or, they might be coming from "elsewhere" and going to a different "elsewhere", in other words, overhead traffic.
Most of us have limited space in which to build a layout, so it's unrealistic to expect to be able to effectively model more than a handful of industries. A single staging track takes up very little space (width-wise, at least) but can represent as many industries as you'd care to have, and can also represent your interchange point with "the rest of the world". My layout will have an interchange track (single dead-end siding) at both the north and south ends of the line, interchanging directly with two different railroads, plus a staging yard at both the northern and southern ends of the line. These will represent not only a connection with a third railroad (the same one, both north and south), but also a lot of unmodelled industries, many receiving multiple cars per session. And, because the industries are not modelled, I can use the same tracks to represent as many industries as I wish - not all at the same time, obviously, but from session to session. Similarly, I have two industrial staging sidings at the south end of the line. These represent an industrial switching district, again with none of the industries actually modelled. The industries there will ship and receive commodities via the modelled portion of the layout, generating traffic and allowing me to use many cars that wouldn't otherwise be seen.
As you can see, the industries that you don't model can be, even if not as interesting visually, as important operationally as those which you do.
Wayne