Crossing the great divide

Jas,

I realize this is a little late now but is there a reason you made the lift-out from wood? How about a pair of aluminum angle lengths tacked together. Fabricate receivers on each piece of benchwork such that the aluminum angle 'bridge' locks into place. Tab and slot like. I am thinking wood lift-out connecting two wood benches will be prone to humidity induced expansion/contraction.

Temperature & Humidity is fairly good here...

Alan we don't have the wild swings in both temperature & humidity like you guys can have here in southern Australia, so timber is fairly stable.  I was also going to prime & paint all the timber on this to stop any swelling that may occur anyhow.

I've also allowed ample expansion around the bridge and the cleats that support it and lock it in, and it will be well braced underneath.  The choice of timber was to provide strength as it needs to withstand a full on assault of someone walking into it, and it easy to work with when shaping the river form that will go underneath the bridge too.

Jas...

Progress from last night...

Well last night I managed to start the cut through the cork & plaster for the downhill grade towards the bridge.  The grade also incorporates the turnout from the new staging area.

The plaster sub roadbed was a good choice and allows the sculpting into various landforms easily.  I have to add cork underlay again and shape that into the finished grade, the path that the new line is taking flows much better than previous and adds a nice little scenic detail with the cut.

Once the cut has been finished I'll be adding the landform base using masking tape and a coat of drywall sealer.

Jas...

Whats that track going to the

Whats that track going to the left into the wall? Obviously that is the outside wall where your garage door is.

The Expanded JL&T

Into staging in the new shed add-on.

https://forum.mrhmag.com/post/exciting-news-for-the-jlt-12197577

Why a bridge?

I do not understand why people must have a bridge on the liftout and duckunder parts of their layouts, as you then need more benchwork underneath the tracks and makes an eventually duckunder more uncomfortable. Why not use a cut instead of the bridge. Then the tracks can rest on the bottom of the liftoutsection,which would be like a plate girder bridge, but camouflaged like a cut.

Expecially in your case, there might be some people traffic between the main layoutarea and the new staging area. Anyway you need a liftout or a swing or liftup bridge. But I think sometimes you would like to more have a nod under than a creep under.

At least, that is what I would like to do.

Replies...

@ Michael, hopefully you had a look at the link Alan provided that explains the new additions (thanks Alan!) this is the "to be constructed" section of the layout that is hopefully starting next week.  This turnout will lead to a 4 metre (13') staging yard with 6 yard tracks which will operated as a classification yard.

@ KnuT, I could use a cut, but it doesn't work for the area and scenery either side of the "lift up bridge".  And because the paper mill addition to the layout which in on the north side of the bridge requires lots of water this is where I will be modeling my water supply from.  Also as I stated in the thread the bridge needs to be able withstand a full on hit from someone walking into it, if it happens so hence the reason for the sturdy constuction.\\

Jas...

A full on hit

Jas, good reasons, and I agree the bridge needs to be able to "withstand a full on hit".

A friend of mine told he had replaced a duckunder that everyone someday crashed into, or more precisely crashed up. Over time the duckunder, just at plank and track, losend and needed replacement.

It's always a pleasure to see your posts, Jas. Thank you for sharing!

Lift Out Bridge - Update...

Well today ended up being a very productive day for the rebuild of the lift out bridge.  I managed to finish off leveling the bridge and grading the track through the cut onto the bridge, I also installed the cork roadbed on both sides of the track this morning.

 

While waiting for the caulk to setup for the roadbed I setup and cut out the bridge canyon through the bridge, at this stage I have only opened up the top and have not cut the sides until I install some more bracing.

 

One thing I learn't from building the first version of the lift out bridge (LOB) was to make sure that you secured the LOB with screws first so that it is in its final position and then lay the cork roadbed and track first.  This way when you make the cuts through the track and ties the alignment should be spot on.

I also had to insert some styrene shims into the southern approach track to ensure the #8 turnout and trackwork was level horizontally and remove any dips.  The track grade is quite steep (in prototypical terms) but it adds a nice little visual break to the mainly flat landscape.

When the roadbed caulk has cured and I have secured the track to the LOB and the approaches I will drill holes through the bridge and into the cleats and insert the guide dowels to ensure the correct alignment of the LOB and the track on the layout.

Lastly I ran a consist across the section several times to test the radius and the trackwork, it had two SD40-2, two 89' TOFC's and two 74' Centre Beam Flat Cars too, all traversed the track without issue at slow and fast speeds.

Next step is to finish the river canyon, install the additional bracing, place braces under the bridge ends and to finish them as concrete piers.

Jas...

Someday...

I am following this thread closely and have already picked up a few ideas for the day when I need to span the gap on my layout.  Thanks for sharing your progress, it is encouraging and helpful.  I am wondering if an upside down L girder would be needed or wanted to stiffen and strengthen the sides of the lift out.  I am using 1x4 lumber, and my lift-out is only 6 inches wide, but even so it will be virtually identical in that there will be a cut-out for a bridge spanning a stream.  In my case, the river bottom will be the stiffener/brace, but you have more width to cover.

Galen

Glad your getting something out of it Galen...

I'm really glad I decided to revisit this and rebuild it.  The track work flow a lot better now than older version, I've freed up more room in the aisle when the Lift Out Bridge (LOB) is removed, and I think the design will work better too.

As far as the L girder construction would go I'm not sure, I have removed a fair portion of the strength from the LOB hence the reason it will have bracing in between.  Our LOB is actually 6" x 1" pine and the reason for this was to get the depth in the river canyon and still retrain some timber for bracing and strength.

Jas...

Great thread.  Is it possible

Great thread.  Is it possible you could show your support where the layout meets the lift-out with any wiring?  Working on this and would appreciate seeing how you did it.

Thanks Cameron

No worries Cameron...

Thanks for the comments.  I haven't fixed the wiring yet, so yes I can take a few photos Cameron to show the circuit that protects both approaches to the Lift Out Bridge (LOB).

The design electrically will be the same as the last LOB, but this time the location of the micro switch will be a little different.

As for the support, the system is just a simple cleat attached to the layout frame work that the LOB sits on.  When I do the alignment pins I'll also post this too.

Jas...

Keys?

Hello:

How is the section keyed to relocate? Will you need to use rail joiners?

Thanks, Carl.

Rail Joiners & Screws...

I had really good success using this method of the old Lift Out Bridge, the rail joiners were soldered to the screw head and the held the alignment perfectly.

This time around I do similar but I'll place the screws and rail joiners in place, re lay the track over the top and solder down so the alignment is perfect and then gut the cap with a Dremel tool.

I'll be working on this today.

Jas...

I have enjoyed your post and

I have enjoyed your post and video. I opted for the hinges that you are using with you lift up. My hinges have a bit of play in them, which I can't get rid of, but have guide pins to make sure it lines up when down. Worked out pretty well otherwise. Also I like your new Banner. I worked for Conrail as an Engineer all through their existence and also have some engines and rolling stock. Did you have any issues with your hinges? 

Lift Out Bridge - Wiring Diagram & Photos...

Hey Cameron & Others Following Along...

As requested here is the wiring diagram for how I have set up the Lift Out Bridge (LOB) on the JL&T.  This is now the second version of the LOB, and it has been realigned and widened to make the track work in this section flow better and allow the installation of the #8 LH Turnout that will eventually go to the Staging Yard.

Wiring Diagram:  Updated.

The wiring above allows for a safety buffer zone incorporated into the last section of track before the edge of the fascia.  So when the LOB is removed it deadens the last 2' - 3' (600 - 900mm) of track work, this way even if a locomotive is running at full speed there is no way they can be launched off the layout onto the floor below.

The small micro switch is the key to the whole idea, it basically takes the positive DCC power for from the main bus and routes it through the micro switch and into the two "safety sections" of track work.  When the bridge is removed the switch deactivates and kills the positive power to these two sections.

You can see that when the bridge is in place the lever on the switch is pushed down activating the switch and allowing power to travel through to the positive rails on the safety sections.

Here is the positive wire from the DCC Main Bus running to and from the micro switch...

From the micro switch the positive wire feeds into a small terminal bock, I have done this because on the northern side of the bridge the safety section has a turnout into it from the Paper Mill.  So this allows all the track work leading into the safety section to be deadened.

The wiring from here (red & black in the above picture) then runs through a small conduit up and over the main entrance into the layout to the other side were it feeds the opposite side of the bridge (safety section).  Again there is a terminal block that feeds only the track feeders that are in the safety section.

The bridge section of track has it's feed from the normal DCC main bus cable, and is connected via a quick release plug so that the LOB can be removed easily.

In the above shot you can also see the cleat that supports the bridge (piece of dressed pine against the rough saw) there are two either side and the LOB is screwed down either end.  I prefer screws because they don't really move at all and ensure pretty much perfect alignment of the rail on the track, I will hide these with some small clumps of bushes with a removable piece to access the screw.

So hopefully this helps explain it all, its really quite easy and a very effective method of ensuring that your valuable locomotives and rolling stock don' take that nasty dive off the layout onto the nasty concrete ravine below...

Jas...

Thanks!!!!

Your explanation and pictures are perfect.  Just got back from vacation, will spend some time looking, over, sure to have questions.  Thanks so much for sharing this.

Cameron

YW...

No worries Cameron, anytime.  Will be adding an over view shot later today to show the safety sections in relation the real track work on the layout.

Jas...