The Bridges at Saltash

[dkightley]

I've been contemplating where I go to follow up The Bridge......a bit of a problem, really! And I've come up with a concept of a design for a layout that includes the three identifiable bridges that surround the landscape at Saltash, just outside Plymouth.

Here's a 3D concept view of what I'm currently thinking of:

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Left to right.....the Coombe viaduct, the Royal Albert bridge (both built by IKB), and the Tamar bridge. Initial idea is to have some form of return loop behind/under the layout surface, and for the road bridge to have moving traffic!

I'd welcome thoughts, etc.......

[Ruskyviewer]

Interesting location there Doug. Quite a busy city landscape with lots of buildings. Looks amazing on Google Street view!
I've had some thoughts about the possibility of looping the track (yellow) out to the edges like "The Bridge" and taking it underneath the inner edge of a curved "C" shaped layout. I've roughly sketched out my idea. This would save work on modelling lots of buildings and roads and help focus the eye on the visible track path over the Saltash bridges. It may also work with an "L" shaped layout.

J.

Saltash bridges layout suggestion - track loop

Saltash bridges layout suggestion 1 track loop.tiff (1.92 MiB) Viewed 21256 times

Saltash bridges layout suggestion - C shape

Saltash bridges layout suggestion 2 C shape.jpg (141.12 KiB) Viewed 21256 times

[dkightley]

One thing I didn't mention in my first post was the size of the layout....which is marked by the rectangular box that sticks up out of the base scenery. This rectangle is 2.6m x 1.6m....which is the same size as six of the aluminium tables I have for The Bridge put together to form a rectangle with a long thin hole in the middle. This would allow me to use a similar construction technique...and re-use the tables!!

After my first post, I worked out I could rotate the rectangular tube round so that the track disappeared off the edge of the layout in a similar way to Jim's idea of a "C" shaped layout. Spin the whole layout round so the taymar bridge is in front of the rail bridge....and it looks a lot simpler to run the rail round into a fiddle yard across the back of the layout:

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The only issue I now have is that the roads running off each end of the road bridge are now at the front of the layout....and will need to disappear under an overhang...or something like that.

[msimister]

And there's also the Southern line that goes under the main bridges and alongside the river that would add further interest - and complication. Doug?

[dkightley]

I'd forgotten that line..... I need to add it to the "plan".

It's a single track.....so that'll be easy to set up an occasional shuttle back and forth. Just need enough space to allow a reversing point out of sight at each end!

[dkightley]

And here's a revised view:

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[dkightley]

With the benefit of six months of taking The Bridge out to shows, I've revised my thoughts to reduce the layout down to a travel volume that will fit in the back of a hatchback.....reducing setup times and exhibitor costs. Here's the current layout plan shown in yet another 3D view.....

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This makes the "viewable " area six feet wide and just over three feet deep with the rear corners angled off to form a roughly half-ellipse shape. There's also a one foot wide enclosure at each end hiding the run-arounds, etc.

[dkightley]

Having spent a lot of time mulling over where I go now following the success of The Bridge.....and "Umming" and "Ahhing" over whether to have a go at Brunel's bridge at Saltash......I've finally come to a conclusion!

My next layout will be called "The Bridges at Saltash" and will be set current day and will feature both Brunel's Britannia bridge and the Tamar suspension bridge.

The Bridge presented me with a few challenges.....3D printing a large structure, creating a multi-board layout that was capable of being operated, transported, and assembled and dismantled by one person......and I think I managed to achieve all of these fairly well. This new layout will also present me with a few challenges that I know will cause me some great interest over the next few months.....

Firstly, there's the transport challenge. I'm aiming to get the layout in a hatchback for transport. This will reduce the cost and hassle of van hire.
Secondly, the railway line is single track over the bridge with a very shallow point immediately at the West end splitting to two tracks in Saltash station. My challenge here is to build a point that looks the job!...and operates as part of automation....which runs neatly to....
Thirdly, I want the layout to be fully automatic in its operation. I intend to have trains running in both directions over the bridge....and back and forth on a branch line running under the East side of the bridges.
And finally..... the model will have the Tamar Bridge, which is a road bridge.......and a road bridge has vehicles on it. My challenge is for those vehicles to be moving! And for there to be four lanes of moving vehicles....and the fast lanes moving faster than the slow lanes!

I've already started doing some design and development work on the road bridge....but I'll not start documenting how I'm doing thins yet - just in case I change my mind! I have, though, decided on the basic layout positioning in relation to the features of the area. Here's a photo of the initial ground image plan, which is essentially based on the latest 3d image in the previous post above:

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[zdrada69]

Doug,
This is really an interesting and challanging project. I looked at some photos of real bridge. I could add one idea and challange. Some sailing yachts cruising moving under bridges !

Pawel

[dkightley]

After getting vehicles moving on the road bridge, moving yachts would be really easy to engineer! No promises....but I'll bear this idea in mind!

[martink]

That will be another impressive layout. The straight-and-narrow concept looks a lot more practical than your original nearly-square design.

It really all depends on decent points becoming available. I'm in the same boat, eagerly awaiting those new ones.

[zdrada69]

It really all depends on decent points becoming available. I'm in the same boat, eagerly awaiting those new ones.

Do you have any experiance with new motorized points ? Are they unreliable ?
Pawel

[martink]

Do you have any experiance with new motorized points ? Are they unreliable ?

I have tried out the manual and one-way ones, and they look functionally the same as the new electric ones. The problems are trains derailing and poor electrical pickup on that huge dead frog, and I simply find them not reliable enough to support any sort of automated operation. The mechanism to switch the point is something else entirely, with lots of options for that - those new ones, servos, Cobalts, etc. Points are one of the reasons my plans for a new layout are on hold at the moment.

I had a long chat with Paul Blake while enjoying his model of Orbost at a local show a couple of weeks ago, and we were both lamenting the point problem and what we could do with some good ones!

And as Doug implies, reliable points are very nearly a make-or-break issue for a layout based on the Tamar bridges. A poor second choice would be to make one line a dummy (maintenance work in progress!) and run trains only in one direction. That old exhibition tradeoff between reliability (especially for a one-man show) and realism.

[dkightley]

I'm going to make ......or get made for me....a custom shallow angle point for the location at the West end of the bridge. The twin track will then disappear off the layout and run round behind the layout....and merge back on the East side of the bridge as a single line.

Behind the scenes there will be a half-traverser sort of point made from a piece of flexitrack fixed onto a pivoted piece of wood or similar....hopefully motorised, as will the viewable set of points. This way, I can have two trains running in opposite directions....

[dkightley]

One of the things that has held up my decision to proceed with this project was the one big "challenge" I was likely to set myself......getting moving traffic on the Tamar Bridge.

Over the past few weeks I've been doing a bit of sketching out of designs for what I was hoping to be a successful traffic movement system that would not look out of place in the relatively shallow profile of the road deck. And I think I've proven to myself that is actually is possible to achieve. My objective was to have two separate mechanical link conveyors...one for the slow lanes and one for the fast lanes.....running under the road deck surface, with a run-around system at each end of the bridge "off layout" so that vehicles move across the bridge and disappear through a hole in the layout backboard....and the a few seconds later reappear running in the opposite direction. And I intend the fast lane to run at a slightly higher speed to the slow lane!!!

So far, I've created a prototype chain link and low profile track in which it runs. Each chain link is approx 0.9mm long and is 3D printed in one piece...and once I get the final design, I'll need a couple of hundred or so to form the two chains. I've also designed and printed a short section of an early design for the road deck.....complete with four built-in tracks. I've sourced and obtained some PTFE strip that will act as the road surface. This strip is a nice light grey colour that will be perfect!! And finally, I've purchased a bag of small magnets ....tiny little buggers as well!!..... for burying in both the chain links and the underside of the vehicles.

Well! Its early days....but I seem to have made quite a good start on what are some of the technical bits for the layout. I'm not intending to post many images of progress on the tricky bits until I get a bit further on with the design and build...but I am taking photos as I go, so will reveal all eventually!

[Patnewbie]

Doug .....that's fascinating to see another special layout beginning to come together I really like way you have altered the view for the layout .... an area I knew well , one thing I find in responses to your posts is how many of us are having to work around the horrible points problem of t gauge , so many needing to find a way to have a working layout without the dreaded points being involved myself included ......always hopeful an alternative arrives eventually for us all ......look forwards to seeing how your work of art evolves in time ......

[dkightley]

Decided to give everyone a peek into what strange things are coming off my printer......

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IMG_3228_red.JPG (53.15 KiB) Viewed 14300 times

These are all test components...

[dkightley]

Its been a few days since my last post......but I've been beavering away on the design and construction of parts for the Tamar Bridge.

I'm concentrating on the automation mechanism for the lanes of traffic at present. I have purchased a couple of drive motors that have built in reduction gearboxes and have fitted a 3D printed pinion to one of them. On the basis that I'll not be able to break the bridge down into pieces for transport, I'm looking at an assembly that will be almost five feet long!!!.....just within the maximum size I can get ins the back of my car!!!

[dkightley]

I've been making some slow but steady progress with 3D printing parts for the road bridge....but things are not yet at the point where I want to post progress shots. Perhaps in a couple of weeks time!

I've got a few parts for the drive system printed....including two of the biggest parts I've printed so far..both overnight printing jobs!

Today, I obtained a copy of a book all about the Royal Albert bridge....which has a number of really useful detailed photos that will help designing the component parts. I'd been chatting with a fellow volunteer at the Tramway Museum and she mentioned she also helps out in the bookshop at Ecclesbourne Valley Railway and they had just got in a as-new copy of a book on the bridge....so I had to buy it!!

[dkightley]

As promised, I now have a photo to show.

Here's a set of 3d printed parts for the assembly at one end of the Tamar Bridge to handle the four lanes of road traffic:

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Top to bottom, left to right.....back row, a two-part chassis (which was too big to print in one piece), supports for the road surface round the run-around wheels; middle row, the end section of the bridge deck with the ramps that feed the traffic onto the run-around wheels, which are next in the picture. Finally the bottom row, the two motors with attached reduction gearboxes and 3d printed pinions, two dirt cheap speed controllers (which I may have a go at seeing how they run trains!!) and the motor mounting clamps.

I need to get some 3mm diameter rod and some nuts and bolts....and see how they all fit together! Kind of sad really....but its "Seniors' Day" every Wednesday at B&Q, so I'll try getting what I want then...and get my old git's discount!