Some turnout locations make it very difficult or impossible to install a DCC/servo controlled turnout because of table structure under the sub-roadbed. This is something that was not taken into consideration during layout design and table construction.
Life is full of surprises.
While careful planning is always best, we have all had similar experiences. Murphy's law will often see to it that a turnout, which must be in a particular spot to make the track plan work, will end up directly over some frame of the benchwork. There are several ways to deal with this problem.
1) Go deep.
If you use a rotating wire inside a tube, "Earl Eshelman" type linkage, where the rotation of the inner wire moves the throwbar, The tube and wire can go deep and right through the obstruction. The servo can then be mounted below the frame member. This is actually more practical when dealing with thick foam, but can be adapted for use in other circumstances. (See first four photos. They were taken to illustrate my $5 switch machine, but the same linkage can be adapted to any switch machine.)
2) Go sideways.
Another form of wire-in-a-tube mechanical linkage uses a push/pull motion of the wire, instead of rotation. This can be extended from the inconvenient turnout location to a place where your servo/ switch motor will more easily fit. For a different reason, I use this type of linkage on my own layout. Being old ans partially disabled, I wanted to eliminate as much crawling under the table as possible. I installed all the motors, frog polarity microswitches, and any other gear that was likely to need repair/adjustment up front, right behind the fascia, which hinges open. Wire & tube linkages and power feeder wires are the only things under the benchwork. (See photos 5 & 6. These show the motors up front, and the linkages connecting the motors to the turnouts.)
3) Move the frame member.
If you use the old 'L'-girder type of benchwork, the stringers, or joists, (which are rigidly fixed in open grid benchwork) can be easily moved. 'L'-girders are also extremely strong, and resistant to warping. One disadvantage of traditional 'L'-girder benchwork is the depth of the benchwork itself. This can be eliminated by mounting the stringers inside the 'L' frame, instead of on top of it. If the stringers themselves are small 'L', or 'T' shaped beams they can simply be screwed in place from the bottom, and thereafter can be moved whenever necessarry. (See photos 7 & 8 This is your basic 'L'-girder made from a 1x3 and a 1x2 pine planks glued in an 'L' shape. The same construction can be used with any sized lumber. I use 1' x 1/4" side beams glued to the bottom of my 1/4" Luan roadbed, to keep it from warping.
4) Go topside.
For a single oddball situation, a servo could be mounted on top of the layout and disguised. This could be done by cutting a place to recess it into thick foam, or it could be hidden inside a structure, or scenery. A horizontal, push/pull type, linkage would connect the servo to the turnout. This linkage could also be buried in the foam. Whichever hiding place you choose, make sure the servo can be accessed when necessary.
Traction Fan :smilie_daumenpos: