May not be prototypical but I mounted (temporarily) the manual switch machine on the bridge deck with the turnout. Doesn't look too bad. Can be thrown using a wooden scewer.
Paul - I'm looking at the under the table Atlas manual switch. Not sure how Rick Van Laar set his up. Can't tell in the photos and video. Most of his turnouts use caboose throws.
Greg's photo above shows the most prototypically accurate method. However, if only the points (to or just short of the closure rails) are on the bridge, you can use an Anderson link with a longer-than-usual upper arm. If mounted to the outside of the rails (thinking of a standard Atlas turnout) it could also simulate the connecting link between the throw rod and the switchstand - which should be safely on the land clear of the bridge.
An Anderson link is, basically, a Z-shaped wire (I use re-bent paper clips) with the vertical in a tube that passes to a point about 1/4 inch below the underside of your roadbed. If the vertical is long - say the height of your bridge abutment - you can use two tubes, soldering the wire into the top of the inner tube and attaching some kind of bellcrank to the bottom to accept whatever you use to move the points. Some of my simplest (paper clip wire and used ball pen cartridge tube) have been in trouble free service since 1980 on my 'end of the railroad' module.
Chuck (Modeling Central Japan in September, 1964)
here's a photo showing a turnout with the points on one side of the bridge and the frog on the other (ganlet in between).
greg - Philadelphia & Reading / Reading
Replicating Rick Van Laar's CSX 4x8 featured in MR.
Look to the prototype. When a 12"=1'0" prototype railroad encounters a situation like this, they usually place the frog at the needed location, but then they extend the movable point rails far enough that the actual points and switch stand are on solid ground. That's the way I've seen it done on conventional prototype railroads. Of course, railroads built on elevated structures (the Chicago or New York elevateds, for example) will place the switch points over the elevated structure.
Tom
I would take another look at the track plan and try to avoid this. It's going to be difficult to keep things aligned to avoid derailments and make sure the points throw properly all the time.
If I had to do it, I would use a Tortoise and hide the wire with....shrubbery! An Atlas under-table mount might work, too. A Peco machine mounts directly to the underside of the turnout, so that's another option, but then you must use a Peco turnout as well.
It takes an iron man to play with a toy iron horse.
Ron,
Check out R/C Models 90 Degree Eccentric cranks for servos, scale of Your size and mount to center of throw bar on bridge, other end goes to Tortoise or machine of Your choice with music wire hidden in hollow abutment area. You can put the music wire in a sleeve under the bridge deckwork, like a brass tube, once painted, won't be seen. I have used that set up before, just not for a bridge, but doable, with patience....my specialty.
Have Fun!
Frank
Perhaps you could use the remote Tortoise mount. The small part would have to go under the throwbar on the bridge (centered or either end of throwbar). Maybe a bit tricky but do-able i'd think. Visible, but you could add a styrene box around it and paint it bridge color and I'd guess only you would notice it.
The Tortoise I recall can be located 18" away. I think the instructions are somewhere on the site also.
http://www.circuitron.com/index_files/tortoise.htm
http://www.circuitron.com/index_files/Page642.htm
There's also an Atlas under table machine. I'm rusty on these so don't know how practical this would be.
http://www.modeltrainstuff.com/Atlas-HO-N-Under-Table-Switch-Machine-p/atl-65.htm
Paul
Modeling HO with a transition era UP bent
I am building a layou where the turnou points are on the deck of a through truss bridge. Has anyone else ever done this? How to throw the turnout? And keep a point rail to either side?
-Ron