02-21-2009, 07:36 PM
A couple of thoughts:
Armstrong omits personal preferences or standards that often become drivers in the layout design. One example is choice of uncoupling method. Using skewers or similar "reach in" devices exclusively for uncoupling really impacts (or should impact) the layout design. Skewer uncoupling pretty much eliminates an eye-level high layout. Even at chest height, reaching across main lines to uncouple cars on a spur can be detrimental to trains passing by on the main. Vertical scenery (tall buildings, etc) can also challenge one's ability to uncouple at the desired location.
The choice of Sergent couplers, with having to ensure an open knuckle and possibly align knuckles for coupling, again dictates easy access to coupling (as well as uncoupling) locations. OTOH, automatic couplers such as Kadee or MT don't couple very well on curves. The LDSIG guidelines say you need the curve radius to be about 5 times the car length for reliable automatic coupling.
Delayed action uncoupling usually requires 2 car lengths of straight track to work reliably.
Where spurs or switching locations connect to a main that is not level requires a system to hold in place the portion of the train left on the main while the rest is switching. This is not always a trivial task. The easy way out is to have track level in all places where coupling/uncoupling and spotting of cars is going to take place. But this can drive layout design significantly.
How turnouts are thrown is another driver of location of spurs and sidings. Manual throws attached to the turnouts have the same limitations as reach-in uncoupling.
The choice of walk-around or central control (if pre-determined) is going to drive the capability to conveniently conduct switching operations at various locations around the layout.
Finally, I like to think in terms of longest train lengths during the design process. The longest train length drives passing siding length, staging siding length, distance between towns, yard drill track length, yard departure/arrival track length, and the length of some yard tracks, too. Failure of any of these to be long enough will create permanent operational bottlenecks, or restrict the longest train length to shorter than anticipated.
Fred Wright
Armstrong omits personal preferences or standards that often become drivers in the layout design. One example is choice of uncoupling method. Using skewers or similar "reach in" devices exclusively for uncoupling really impacts (or should impact) the layout design. Skewer uncoupling pretty much eliminates an eye-level high layout. Even at chest height, reaching across main lines to uncouple cars on a spur can be detrimental to trains passing by on the main. Vertical scenery (tall buildings, etc) can also challenge one's ability to uncouple at the desired location.
The choice of Sergent couplers, with having to ensure an open knuckle and possibly align knuckles for coupling, again dictates easy access to coupling (as well as uncoupling) locations. OTOH, automatic couplers such as Kadee or MT don't couple very well on curves. The LDSIG guidelines say you need the curve radius to be about 5 times the car length for reliable automatic coupling.
Delayed action uncoupling usually requires 2 car lengths of straight track to work reliably.
Where spurs or switching locations connect to a main that is not level requires a system to hold in place the portion of the train left on the main while the rest is switching. This is not always a trivial task. The easy way out is to have track level in all places where coupling/uncoupling and spotting of cars is going to take place. But this can drive layout design significantly.
How turnouts are thrown is another driver of location of spurs and sidings. Manual throws attached to the turnouts have the same limitations as reach-in uncoupling.
The choice of walk-around or central control (if pre-determined) is going to drive the capability to conveniently conduct switching operations at various locations around the layout.
Finally, I like to think in terms of longest train lengths during the design process. The longest train length drives passing siding length, staging siding length, distance between towns, yard drill track length, yard departure/arrival track length, and the length of some yard tracks, too. Failure of any of these to be long enough will create permanent operational bottlenecks, or restrict the longest train length to shorter than anticipated.
Fred Wright