With the modelling room finally coming to fruition, the time has arrived when a final path for a branchline to this room has to be decided and implemented. The reasoning for the provision of this line was originally borne out of the simple fact that the new room adjoined the layout room and would give the opportunity to transfer locos and rollingstock to a dedicated servicing, repair and maintenance area away from the layout without having to handle them unnecessarily.
Over time is was realised that this room and associated terminus, would also facilitate a need for an "as required" transfer movement where during normal running sessions...any piece of faulty rollingstock could be placed on a chosen "repair" road at Fish River yard and then when decided a special train would transfer this stock to the modelling room. Indeed it may well end up that a mainstream terminus with station and yard may morph into being and in time this transfer branch may end up being a revenue style destination requiring a variety of passenger, freight and mixed style trains. In the meantime I have been examining the best way of branching off already laid track to give access to the modelling room.
To understand the issue at hand, I guess that a little history is warranted so that the casual reader can follow my logic a little better. Fish River was always planned to be the centrepiece of the layout and was to be a medium size station and yard, situated between two major centres and serviced by a double track mainline. Over time I made the decision to trim back my planned "empire" and reduce the layout to a single mainline. With this decision made, I decided to leave the already laid "up main" in place and utilise it as a passing loop with the up extension between the branchline junction, across the Fish River bridge and as far as the double track tunnel portal, as a shunting neck. I guess the prototype equivalent for this main line rationalisation would be sections of the Main Western line in NSW. In the down direction from Fish River the main and loop revert into a single line as they leave town.
My idea was for the previously described shunting neck to be extended...but because it needs to cross the main line to get to the modelling room... grade separation was a possibility to cross the main and then enter the modelling room. The problem with this plan was that the bench height in the modelling room is governed by the window sill height in that room and if the line entered this room under this plan, it would be around 180mm higher than the bench height and would also severely impede one window...not really workable. So the most recent plan is for a diamond crossing to be installed just beyond the tunnel mouth ( in the hidden siding room) and for the two tracks to now be transposed in orientation and entry to the modelling room should now only be around 50mm above bench height...certainly not the most conventional method of overcoming the problem...but it certainly avoids track sharing via points etc and does not require any grade separation. It must also be stated that all of these modifications are unseen and occur in an "off layout" area.
The chosen method will also have an added bonus of exposing me to a diamond crossing as I have never utilised this type of unit...and I have also chosen a Tam Valley, Frog Juicer to look after the frog polarity issues...so this will be an opportunity to learn some new aspects of the hobby.
I have included some diagrams of the layout so as to aid the reader...