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1/72 Maritime Lift-Span Bridge


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Antiquated console (1964-1995), of Wardell Bridge.

Was in storage by the electrician who replaced it with a newer version (1995).

Arrived to the Ballina Naval and Maritime Museum (2016).

Reassigned to operate a model of the Wardell Bridge (2017). 

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The museum had not enough room in their workshop to include this display table as well. So it is being built in my lounge-dining room (I have no garage).

Once the timber arrived I marked all the pieces, cut them out and assembled them like a kit. I was pleased that there were no hiccups.

All tabletop screws were countersunk, filled with wood putty, and sanded back.

 

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The line you see across the table is a 3 mm gap for guiding the boat under the bridge.

 

Below is a drawing of how the pulley-cable system is to operate.

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The motors, pulley-cable systems, and various electronics will be housed into a control box.

This will be mounted under the display table. Two doors are added for ease of access to those parts.

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The first thing I did was mark out the centre of where the footings go. Then drilled holes for inserting 3 mm bamboo skewer sticks for doweling.

From scrap board I cut out the footings and filed them into shape. Then drilled their centres and positioned them over the doweling; gluing them into place.

 

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Used wood putty to remove any shadow line between the footings and water. Drilled the piers and glued them into place. Each set of piers have their own length because the bridge is curved/arched. Bracing was also added.

 

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Then the girders were added. The loose board is the span base plate.

The boxed area at one end is where Bridge Street goes under the bridge.

 

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Thank you @martin_sam_2000, @Silenoz, and @southwestforests for encouraging words.

 

2 hours ago, Silenoz said:

Reminds me to a similar project I've seen elsewhere a while back, is that possible

 

@Silenoz, yes that is possible. I have this project shown as a WIP in other forums.

The project is about half completed and still has many months to go yet.

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Gave the bridge, and the river area, a few coats of white acrylic undercoat. The holes you see at the bridge ends, where the span sits, is for contact wires. These feed power and data to the lift-span, for such things as navigational beacons and vessel traffic lights.

 

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On either side of the bridge are several Fender Piers. The outer groups have navigational beacons on the center piers (drilled out for wiring).

 

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Somewhat sort of related content; and your next model. 
As it happens the current issue of Trains magazine which is by the company publishes Model Railroader, Garden Railways, and Fine Scale Modeler, has short article about a unique lift bridge, 

 

https://bridgehunter.com/wa/pierce/bh46496/

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Description 

This bridge is nationally significant as the only remaining example of its kind in the United States, displaying the unique patented design that Strauss developed. This type of vertical lift bridge avoids the use of traditional towers and cables. The only other currently known example of this type is located in Prince George, British Columbia.

 

 

http://historicbridges.org/bridges/browser/?bridgebrowser=washington/chambersbayrailroadbridge/#photosvideos

 

Quote

 

Bridge Documentation

View Historic Structure Reports For This Bridge

This is the only remaining example of a Strauss Direct-Lift bridge in the United States. The only other known example in North America is located in Canada, at Prince George, BC. View the Prince George Bridge page for a more general discussion of the direct-lift type, including links to the patents and other documentation about this bridge type.

Designed and patented by famous engineer and bascule bridge proponent Joseph Strauss, it is perhaps not surprising that a Strauss direct-lift bridge combines the technologies of the bascule bridge with that of the lift bridge. The movable truss span raises up like any vertical lift, however the lifting motion is controlled by two bascule-like counterweighted arms that are linked to the lift span and rotate around trunnions.

Charles Louis Strobel who ran another Chicago-based bridge company called Strobel Steel Construction Company also had his own variety of direct-lift bridge... with just enough differences so as to avoid patent infringement. No examples of Strobel's direct-lift bridges remain today.

The Chambers Bay Railroad Bridge is nationally significant as the only surviving example of its kind in the country. A very unusual design, it was built to the patents of a famous engineer. The bridge appears to retain integrity of design and materials. For all these reasons, this bridge should be included among the most historically significant movable bridges in the country.

 

 

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@southwestforests, thank you for those very interesting bridges. Never seen that type before. 

If I ever build another bridge, it would be this type for sure.

 

Since starting this project, much information learnt about scale modelling scenes come from railway modelling. I like the working parts of it all. I may start a new hobby in railway, and if I do, this type of lift-span bridge would definitely be in it.

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Throughout the project I have been scavenging parts from unserviceable electrical appliances, TVs, PCs, etc. The heatsinks used on the Power Supply Unit (PSU) were from PC PSUs.
I needed a small pair of speakers for certain sound effects (alarm bell, boat engine, and perhaps a fog horn). Found a good pair of speakers from an old analogue TV set. However, the diaphragm was exposed and I had to make a mounting bracket so the diaphragm would not touch anything (or it would muffle the sound).
 

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While I was at the museum to cut out speaker holes, etc., out of the console, there was talk about showing photographs of the console interior as part of the display. Then I opened my big mouth and said why not replace the front panel with a sheet of thick clear Perspex. So now the console will also be a diorama of sorts _ a wiring diorama. This means that the interior needs to be cleaned up, painted, and revamped. Though the control panel will also be revamped its antiquated looking exterior is to remain as is.
 

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Added 3 mm Masonite sheets for road base, kerbing, and footpath to span plate.

 

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The underside has red and green navigational beacons, plus 8 contacts (shown later). To hide the wires, I decided to carve out trench to route the wires to far side of span where the framework will be. Then the wires can be attached to the framework and routed to the span hut without being too noticeable.

 

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Then I drew up a template for the framework and started making the span frame. Used 2.5 mm bamboo skewer sticks for doweling wherever I could.

 

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While building the frame a solution anchoring the span cables to the frame came to mind. I used half a fishing swivel attached to a bolt head. Any twisting tensions on the cabling will be neutralized by the swivels.

 

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Then I placed the span on the bridge to get an idea of how the rest of the bridge may present itself.

 

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I found some springy shim metal and cut out eight contact plates. Installed the contacts, LED navigational lights, and wiring.

The wires are routed to where the frame vertical beams are, so to guide the wires to the span hut.

 

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I filled the trench work with wood putty (after I checked for electrical continuity). Then sanded and painted the span with white acrylic undercoat.

 

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Luckily I came across a few photographs of Wardell Bridge via a Company that uses drones for aerial photography. Form these photos I was able to draw a plan for the span hut.

 

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The base plan:

 

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Used 3 mm MDF board for hut and gangways, and matchsticks for rail posts.

The extra board you see is the hut floor. I am going to used its edge for gluing the hut walls to.

The rectangular hole is where the wiring will come up from under the span.

 

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You can see the cable anchoring points have been inserted. I used microswitch actuator arms (the roller type) for bumper rollers. These ones are for longitudinal movements of the span. They are to stop the span from getting caught onto the towers when the span raises and lowers. On one corner is also an opto-couple used for triggering the vessel traffic lights from red to green once the span reaches its upper limit.

 

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The wires got routed to the hut. Glued the wires against the framework for concealment.

 

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