Loren,I fully agree that any layout calls for good solid LDEs...Without a solid design a modeler can lose interest in running the layout and this applies to the industrial switching layout to basement size empire. However,we must not overlook the new modeler that builds a 4 x 8 foot layout adds 3 or more industrial sidings and enjoys running his layout making laps and dropping off cars.Oddly he/she does this without operation books,layout design books and I dare say input from forums yet he/she has found operation in its simplest form on a simple basic loop layout.
As far as industrial switching layout planning that is more complicated then the average basement empire..Switching puzzles like the time saver is to be avoided in designing industrial switching layouts after all you want to enjoy switching your industries.
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Ralph,I have seen that question ask on other forums and seen some down right ridiculous answers such as "Tear it down and start over".

After designing and building the layout one should enjoy the fruits of his labor by operating his/her layout after no doubt they have thousands of dollars in locomotive and rolling stock plus thousands more in the layout.
As far as continuous running at train shows and open houses try this..Switch the yard and see where the crowd gathers.Now add trains entering and leaving that yard you have a crowd pleaser..We see this time and again at out clubs open house..Of course we have a point to point layout with a single track main with passing sidings.
Listen.We have a engine working the yard another engine working the passenger terminal,locomotives moving from engine terminal to outbound trains,engines going to the engine terminal and some times a outbound train passes a inbound train before hitting the single main..Guess where most visitors stand? Yup where the action is the yard area..The hump yard is a crowd pleaser as well.We even run a local and folks enjoy that to.
BTW All of this is done by the magic of DC...
Another thing the visitors likes is looking at our CTC board.They ask loads of questions especially about how we know where each train is and how we decide where they pass?
And IMHO that is the way a open house should be..
On the down side..Why does some modular clubs insist on running 3 trains in the same direction..Don't they know that looks more like racing then anything else?
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Gary,I have notice that to..I can not help but wonder if they ever run their trains? I have visited layouts that had more scenery material sitting on the tracks then engines and cars.
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Miles,I will not design a layout without prototypical operation as the main goal.After all I want to use my locomotives and cars in that manner.
Even my industrial switching layouts is designed for the best operation possible..