Lift bridge hinges?

Assuming that you are simply looking a a plain platform for your tracks, you would want the hinge PIN to be at least 1/8 inch higher than the TOP of the rails. This will allow the railheads to clear.

Remember that the other end of the lift has to be beveled in to prevent catching on the vertical part of the opening. 

I have three lift bridges, hinged in the same manner as per Swav's comments. One additional fact that I determined, using the Gargraves Phantom tin plate track, the cut ends of the track segments on the lift deck and adjacent stationary track are slightly flexible left to right.

Using clear silicone, I applied clear silicone to both the inside and outside sides (webs) joint of each rail and the last wood tie on the lift bridges and adjacent stationary track wood ties using a small flat screwdriver, the silicone was worked into the web-tie joint both sides and a slight bevel left on the outside 90 degree corner of the rail web and top of tie.

This eliminated noticeable gauge gaping at the rail end crossover joints and should also prevent longitudinal walking of the individual rails in the wood ties and possible binding in opening the lift bridge.  

I have found these hinges perfect and very inexpensive.  I have installed them on 3 different layouts, the pictures are of mine and it has been in place since 2006, with the bridges.

The bridge in the foreground is a MTH bridge.  I did not use the base of the bridge, but had a piece of sheet metal cut to fit.  And mounted the track to it.  (The opening space and bridge length could have been designed better, but I did not want to give up table space.  The two curved bridges are home made.  I just had the sheetmetal base cut to the same radius as a section of 072 track.  I had a gusset added to the bottom of the base so the bridge would not twist.  (I wired the track ON the bridge and have isolated track sections on the open side, so if the bridge is open and a train approaches it stops automatically)

Hinges available at hardwaresource.com  their SKU number is 732022 Cost was $6 a pair.  I added a flat metal extension piece on the fixed side of the hinge just to provide extra bracing when they were secured to the layout.

I used these for track pins.  These would be used on the "open" side of the bridge in the track where the bridge landed.  They even helped with the alignment and make a good connection with the beveled edge.   Available at train stores or Gargraves.  (Nothing wrong with installing an alignment pin for the bridge either.)  I haven't. thought I would if needed, couldn't guess how many times my bridges are accessed but never been a problem.

Don, thanks for the photos, explanation, vendor, p/n and other information.

Don, how long and wide is the MTH bridge?  I have a drop-down span made of plywood with 1x2 bracing underneath that I want to replace with such a bridge.

The problem is it's the tail leg of a Wye so the bridge would have to be wide enough to support it.  The current design is approx 15" wide at the widest part and 42" long.

The bridge in the foreground is from MTH, 

It is 32x10 15/16 x13 Product Number 49-1062, $99.

The two in the background were custom made based on a section of curved O72 track.  I took it to a plumbing/sheet metal shop and had them cut me a piece of .032 sheet metal as the base, and had them put a gusset as a stiffner on the bottom.  As it turns out that was really a good thing.  When my scale Big Boy crosses it, the boiler swing is so wide that it extends over the top of the side when crossing.  I wouldn't think it would matter with the WYE as long as the switch is on the table top.  Constant movement of the switch would be really tempting fate in my opinion.

I could just about mount the bridge sides onto the flat piece I have now and it would probably be good enough.  Even if it's 32" long I could maybe build some Faux bridge footings to blend it all in.

It might be best to buy/make some girders and attach them to the 1x3 (not 1x2) bracing underneath the surface plywood.  The piece that swings down is flat on top:

The diagram above shows the drop-down at the Wye.  The drop-down is 15" wide on the left side and only 6" wide on the right (the diagram is a bit out of scale in that area).  It is hinged (2 regular door hinges) on the 15" side to allow access to the room.  On the right hand side I have a round latch (used for outdoor gates) that keeps it in place when it's raised, thru a hole in the side of the layout frame.

Here's a photo of the drop-down section I have now:

Even though it's technically still a "Wye" I'm using an 072 left hand switch on this end of the Wye.

Bob,

We always seem to need a bridge in one of the worst places on the track plan.  But, it is, what it is.  So given the scenario you have I think I would try the following;

1.  I don't think the MTH bridge is of any benefit to you with the WYE.  And the bridge is a 2 track bridge.  I don't think it would look right.

2.  Definitely think you need to use a sheet metal base as opposed to wood.  Want to avoid the weight of the wood.  And could cut down the width to maybe 3" larger than the track layout.  Ending with one straight side and one curved side.  (I would fab the intended bridge base out of plywood.  And use that as a templete for the sheet metal.

3.  I would hinge the bridge on the wide end using a minimum of 3, preferably 4 hinges.  Certainly would NOT want that mass suspended by hinging  the narrow end!

4.  Then I would use girder type bridges or just girders (similar to my curved bridges above)

I don't think it would be too difficult to do.  I would suggest that on the right side of the photo that the smaller end of the bridge land 3 or 4 inches onto the layout.  It makes everything so much more stable, and accommodates track connection and alignment as well.  By having the sheet metal made, it isn't that costly if you decided you didn't like it you wouldn't be out much.

Hope these thoughts help some, and I'm sure you will have fun.

Thanks Don, this will be a project for sometime this year.

Here is mine crossing the entrance hinges are above track height and supported in up right position by storm door closers.

Looks great, Don. 

When you can, how about a couple of photos of the hinge side and open side (bench and bridge ends)?  It's great that you posted a magnificent bridge in a lift up setting, but, from a practical perspective, close-ups showing how you did it would be of equal value.

Again, great bridge and photos; thanks for sharing.