Q: How do you make a siding accessible to both main lines [northbound and southbound]? I can see this being accomplished with a double crossover prior to the siding from both directions. Q: Is this the best method? Q: Or, do you simply limit access to one main line [i.e north bound trains only]?
Perhaps my understanding of a double main line needs clarity.
Q: Do double main line layouts merely have sections of double main line [otherwise called passing sidings] and a single mainline through areas that have sidings?
The simplest method is to simply have a crossover before the siding turnout running in the same direction.
The siding will in all probability need to be accessed by trains running in either direction. For that you need a runround. A cross-over in each direction will be required, preferably a train length apart.
It's quite common for industrial sidings to only be accessible from trains in one direction.
Is your double main line one up and one down (East/West) or two bidirectional tracks?.
This all depends on traffic density. Where there is a single mainline with passing tracks (loops/sidings) trains running in opposite directions tend to spend a lot of time waiting. The more intensely utilized a single mainline is the more wasted time is built up.
No, a single crossover at each end will suffice: ----------------
Depends on the situation.
You can... it would mean, for example, that a northbound train from Alpha with deliveries for Beta Industries might have to take them all the way to Delta Yard, where a local would take them back out down the southbound side to Beta... or you could indulge in a little "opposite main running" to reach them. Fun stuff for the dispatcher!
A double main is NOT a single main with passing sidings - it's true double track main, with one-way traffic on each line (usually). With appropriate crossovers, you _can_ use the opposite main as a passing siding if the schedule permits...
My next layout is in the planning stages right now - it's going to be a double main point to point (with loops around the terminal yards so I can sit back and watch the trains run if I want to... so topologically it's a multi-deck dogbone). Total length of the run will be about 10 scale miles in loop mode. Some of the industries will only have access from one side or the other. There's going to be a town in the middle with a smaller yard that serves as the turning point for locals from each end, and of course there's the through freights and high-speed passenger service on its own dedicated line (not gonna make the Amtrak mistake!)
As I understand old time operations, a siding was only serviced by trains operating in the direction opposite the opening of the switch. IOW if you had a train going eastbound on a right hand RR with a load destined for a siding off the opposite track and the siding merged with the west bound track going west, the load would continue east bound to the next yard or siding where it could be picked up by the next job heading west or if was already a part of a local then it would continue to the end of the run and be dropped on the return trip. In the northeast, at least, a typical job would run out and back in less than sixteen hours with one crew change at the eight hour mark. So to lessen time making complicated switching moves the cars were simply dropped where the return run could pick them up for delivery either at a small yard or shared siding.
Thanks for a terrific collection of ideas to explore in my design process. I can easily see a combination of these approaches to vary the experince for a train operator.
I very much like the center siding w/ a "Y" at each end. The drop off and return run by a local adds a nice wrinkle to the waybill system as well.
I must admit. I enjoy the design effort as much as anything. I have a large drawing that has been in process [many edits] for two years. It seems that each train show and/or magazine article generates another 'idea' that warrants consideration. Out comes the eraser, and I begin exploring a new switching scenario, locating a nw bridge, or creating another interchange yard.
I did conclude that the best scenaro [for me] is to have a second floor layout with a circular staircase that creates entry somewhere within the middle of the layout room. I want to avoid the dreaded duck under, yet I like the around-the-room layout design for a number of reasons. I would like to have hidden staging at two ends of the layout with both yards being in a separate room to complete the separation between the on-layout and off-layout train movements. The *mole* job has lots of upside in my view [it could be a great assignment]. Hence, I hope to create a hidden staging space that furthers the enjoyment of that job.
I'll reinforce the operation aspect of doing such a thing. The prototype runs through trains from one terminal to the other. It generally doesn't do any switching while on the road unless the business takes a large number of cars at one time which will make it profitable for the road to switch the cars with a through train. The cars would be a cut at either the front or back (prefered) end of the train. The usual process is to haul the cars all the way to the terminal and then have the local train deposit the cars to the local industries. If the business is on the wrong side of the tracks (beyond the other track) there are two choices, the first (normally done) is to haul the cars to the end of the run for the local and then crossover to the other track where there will be the necessary facilities (usually two crossovers spread some distance apart so the engine can run around the train) where the business on the far side of the tracks then becomes the near side and the businss is then serviced. If the siding is a facing (you go into the siding with the loco first) the road may run those cars for that industry first in front of the loco.
-- Why do penguins walk so far to get to their nesting grounds?
Growing up in Chicago in the fifties we kids would watch the local switcher do a flying switch to drop off the caboose. When travelling at about ten miles per hour, pulling the caboose, the brakeman would uncouple the caboose from the locomotive. The engineer would "floor it" to open up some distance between him and the caboose, and right after the engine had passed over the facing switch a brakeman on the ground would throw the switch and the caboose would majestically glide into the yard.
Great fun to watch but probably impossible to replicate in HO. Maybe G scale.
I'd believe that it was more common on CTC controlled systems as otherwise the siding would be taken up by a train going the other way which got out of the way of something that needed to go past it like a passenger train. The CTC operator would then know if the siding was occupied or going to be occupied. on unsignalled territory, it would be dangerous to have such a siding as a train could enter from each end and thus have a disasterous meet somewhere in the middle.
-- Why do penguins walk so far to get to their nesting grounds?
My local station has a double track suburban line, with a siding to an adjacent flour mill. Left hand running. Train of loaded grain hoppers arrives from town at down (north bound) platform. Then backs through a turn out across the up (south bound) main line by way of a single slip. The flour mill siding has two roads,full and empty. The loaded train sits on the full road, the loco is detached. Loaded hoppers are shunted (switched) two or three at a time from the full road across to the empty road by the local rail tractor (minature switch engine) and then pushed over the under track hopper into which the grain is dropped. When all hoppers are empty and made up into a train, the train loco runs aound to the city (up, south) end and couples up. Then the empty train is pushed out across the single slip onto the down line. When clear on the down line, the train, with its loco at the city end, then sets off across the single slip and onto the up (south bound) line and so off to town. These movements are done smartly as the double track line has a fairly frequent suburban EMU service along it. Whilst they are being done, main line signals in both directions are, as to be expected, at danger. Regards,
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