Lift Span Bridge

[Sparky]

Hello forum members.

I am new to model making. This project I am currently doing, and been doing for a long time, is for our local maritime museum.
It has nothing to do with railway, though I wish it did. Unfortunately, the railway here did not directly service the Port of Ballina, (NSW, Australia).
The actual lift-span bridge is 25 km south of Ballina, and located in a small town called Wardell.

My background, when I was younger, involved welding, diesel mechanic, and avionics (RAAF). Today I do volunteer work for the museum. It was the avionics side which got me roped into doing this project. The museum acquired the original console for the bridge. The bridge had two updates since then. I was asked if the console could operate a model lift-span bridge. My answer was yes. So now they got me to not only convert the console to do the job, but to build the model bridge as well.

I soon discovered that there is no schematic diagrams for the console, or any available (to public) plan drawings of the bridge. The bridge and console go back to 1964. So the whole project is scratch-build. one good thing though was that the current bridge operator was able to decipher how the control panel was used.

Here is a photograph of the original bridge.


The original console in the museum workshop.


The museum is a non-profit organisation and is limited with funding the project, so I too am limited with what materials and parts I can use. So bare with me if you see me using, or making bits, which you know I could have bought from a hobby shop. I do a lot of Internet research for available bits, but if they don't suit me, or too expensive, then I use alternative methods.

Hopefully some of the forum members will be interested to see this project unfold. If so, I will start downloading photographs at a piecemeal rate.
The project is currently about half-way to completion.
The allocated display table area is 2400 x 1200 mm (8 x 4 feet).

[tct855]

Sparky,
           G'day,
                  This is really one cool bridge!  Can't wait to see and learn more!
                                                                                                                Cheers!     Thanx Thom...

[Zephyrus52246]

That console has a lot of buttons for something that only needs "up" and "down".      Looks like an interesting project.


Jeff

[GPdemayo]

I'm looking forward to seeing your build.....welcome to the forum. 

[postalkarl]

Hey Sparky:

That is quite the project. I will be following along with great interest. Keep the photos coming.

Cheers:
Karl

[bparrish]

Sparky...

Welcome aboard.

see ya
Bob

[PRR Modeler]

Welcome and looking forward to seeing your build.

[Sparky]

Wow, thank you Thom..., Jeff, Gregory P. DeMayo, Karl, Bob and Curt Webb for your interest.

Yes, it is a large project (for me it is) and I sure do not want to let down the museum by not meeting their hopeful expectations.
I too am looking forward to seeing how it will look and operate. I often hand over my concerns to God, or else I will self destruct out of self-doubt.

[Sparky]

That console has a lot of buttons for something that only needs "up" and "down".      Looks like an interesting project.
Jeff

I thought the same thing when I first saw the console.

Much of the control panel labeling did not make sense to me. I took a photo of the panel to the current operator to learn how to operate the bridge. He told me that he never saw the panel before (it was taken out in 1995), and that he cannot tell me how to operate the bridge (some security thing). However he was able to decipher what each item did.

After I got back home I sat with my notes and slowly worked out how each item may be used in operating the bridge. It is quite sequential, and it needs to be for safety reasons. In a nutshell, the console controls the traffic for both road vehicles and river vessels even before unlocking the lift-span from the bridge.

There is a larger problem with operating the console. The museum wants the display to be interactive. Meaning, that visitors can operate the bridge  Suddenly, the whole idea of only mature people operating it went out the window. It now has to be child-proof. In other words, nobody is allowed to drop the bridge on the traversing vessel, or any other possible mishaps. It needs to be sequential without possible deviations. Unfortunately I am not up to date with using programmable microcontrollers (PIC) and such, though I am learning for future museum projects. So I am currently relying on electronics and relays to do the job.

Here is the control panel, and underneath is a simpler layout drawing which I have stuck on the wall at my desk.



You will notice that the bridge uses swing gates to close the road. Today they use a boom gate, a simpler and safer method.

[Sparky]

I used Google Maps and Internet search engines to find as many photographs of the Wardell bridge. Then, with a tape I measured the length of the span and the width of the road crossing the bridge. With these two lateral measurements I was able to extrapolate the other measurements from the photographs.

The display are the curator wanted me to use the whole bridge within the 8 feet allocated for it. This worked out nicely for a scale 1/72, and I drew up plans accordingly. This was before I realized that a better scale 1/76, OO scale, could be used for greater access to modelling resources.

An overview.



Display area.



Decided to use a pair of (donated) DC motors, geared down 148:1 to drive the working parts. Since the bridge uses a pulley-cable system, I decided to use similar for the traversing boat. Both these motors will be housed in a control box under the display table.



The first month or so, on the project, was designing and drawing up plans so I could follow how, with the available material, to build the project. Here is a montage of some of my drawings.



For those unfamiliar to a lift-span bridge, this is how they work to allow large boats to pass under the bridge. (Animated GIF)

[oldiron]

Ok, here we go. I used to overhaul "moveable structures" for a living. I'm in the US so it looks like there are some differences in terminology down under but the basics look the same. An opening sequence would go something like this;
1. Turn traffic lights red. I think that would be your switch labeled "Control Switch". Off is normal, traffic lights dark. Control position would start the sequence to turn the traffic lights red. When they go red the "Road Lights Red" indicator would light, a safety circuit would clear allowing movement of the gates and the "Gates Movable" indicator would light.
2. Lower oncoming traffic gates. Oncoming first so you don't trap anyone on the bridge
3. Lower off-going traffic gates. When the last gate reaches full closed another safety circuit is cleared so your span locks will operate and the "Lift Span Lock Operable" indicator would light.
4. Retract the span locks. I would guess that's the lever on the lower right labeled Extend, Off, Normal. Turn the switch to normal. When the locks fully retract yet another safety circuit is cleared enabling the lift motors and lighting the "Lift Span Operable" indicator light. A little something might get lost in the translation here but by US Coast Guard regulations navigable waterways have the right of way over all other traffic hence the "normal" condition is locks retracted, and bridge up.
5. Raise the bridge using the "Span Control" buttons.
6. A little guess work here. In the US the navigation lights both ways turn from red to green then the bridge is fully open. In your case it looks like once the span reaches fully open a interlock circuit will clear, lighting the "Nav. Lights Operable" indicator and allowing you to select upstream or downstream traffic using the "Navigation Lights" switch.
Time to lower it down.
1. Navigation Lights off.
2. Lower the span, changeover switch to off.
3. Extend the span locks, switch to off.
4. Open the off-going traffic gates, switch to off.
5. Open the on-going traffic gates, switch to off.
6. Turn the traffic lights green
7. Once traffic is moving, secure the board by turning the control switch to off.
The "Lift Span Motor" meter is an amp meter to tell how hard the bridge is moving. Without it you have no idea if something is binding until the parts start flying. The last bridge I did, a 4 leaf double bascule, had 8 drive units producing 1.2 million foot pounds each. If something goes wrong that'll
leave a mark. The "Changeover" switch is to select the back-up drive incase someone wasn't paying attention to the Lift Span Motor meter. Another useless tidbit. Drawbridges are overcorrected, if the brakes are released they fall slowly UP due to the too heavy counterweights. Bob H.

[S&S RR]

Very nice project, thanks for sharing it with us.  Welcome to the forum.  I will be following along with great interest.

[Sparky]

Thanks oldiron and S&S RR for your interest.

[Sparky]

Hello Bob. Your summation was very good considering the control panel was not well labelled.
Here is my understanding of the controls, overwriting the differences in blue.

Ok, here we go. I used to overhaul "moveable structures" for a living. I'm in the US so it looks like there are some differences in terminology down under but the basics look the same. An opening sequence would go something like this;
1. Firstly, the CHANGEOVER switch is for Power (NORMAL = Grid electricity; AUXILLARY = Back-up diesel generator). So this switch is put in NORMAL position. This empowers the CONTROL SWITCH and the NAVIGATIONAL LIGHTS switch. The NAV. LIGHTS OPERABLE lamp is now ON.

Normally, the road traffic will flow with the traffic lights being OFF, or 'dark' as you put it. Turning the CONTROL SWITCH to CONTROL empowers the Traffic Control switch (unlabeled) at bottom right. Also the navigational lights under the span and on the Fender Piers turn on. In reality this is optional, and usually are turned on, when needed, between dusk and dawn. However, with the NAVIGATIONAL LIGHTS switch in OFF position the red control panel lamps, for up and down-stream, will be ON. The vessel traffic lights at center of span will be red for both up and down stream. So no vessels ought to be traversing under the bridge.

Turn traffic lights red...
In Australia we have Red, Amber, and Green road traffic lights. The switch at bottom right is for traffic control lights. NORMAL = has the Amber traffic lights flashing, and an alarm bell, for about 15 seconds before it stops and the red traffic lights come on. However, due to possible traffic delays, the operator may wish to EXTEND the Amber flashing lights until the bridge is clear enough to have the red lights on. The operator (pre-1995) used an inverted periscope, in the span hut, to see if the traffic (and pedestrians) were clear off the span, or between the swinging gates.

Once the Amber stop flashing, the red lights come on. The ROAD LIGHTS RED, and GATES MOVEABLE lamps on control panel is ON.

I think that would be your switch labeled "Control Switch". Off is normal, traffic lights dark. Control position would start the sequence to turn the traffic lights red. When they go red the "Road Lights Red" indicator would light, a safety circuit would clear allowing movement of the gates and the "Gates Movable" indicator would light.
2. Lower (CLOSE = gate swings across the road) oncoming traffic gates. Oncoming first so you don't trap anyone on the bridge
3. Lower off-going traffic gates. When the last gate reaches full closed another safety circuit is cleared so your span locks will operate and the "Lift Span Lock Operable" indicator would light.
4. Retract the span locks. I would guess that's the lever on the lower right labeled Extend, Off, Normal. Actually, there was a hand-lever next to the console, similar to a railway points lever in a Signal Box. Now a normal switch has been added to the control panel to replace the hand-lever. Turn the switch to normal. When the locks fully retract yet another safety circuit is cleared enabling the lift motors and lighting the "Lift Span Operable" indicator light. A little something might get lost in the translation here but by US Coast Guard regulations navigable waterways have the right of way over all other traffic hence the "normal" condition is locks retracted, and bridge up. Once the LOCKING PIN switch is in the UNLOCK position (not shown in diagram) the LOCKING PIN DISENGAGED lamp turns ON. The LIFT SPAN OPERABLE lamp turns ON when the NAVIGATIONAL LIGHTS switch selects up or down stream. This enables the vessel traffic lights, for up or down stream, to turn green when the span has been fully raised.

5. Raise the bridge using the "Span Control" buttons.
6. A little guess work here. In the US the navigation lights both ways turn from red to green then the bridge is fully open. In your case it looks like once the span reaches fully open a interlock circuit will clear, lighting the "Nav. Lights Operable" indicator and allowing you to select upstream or downstream traffic using the "Navigation Lights" switch. Once the span reaches its upper limit, and only then, does the green light for the boat comes ON. The bridge operator will be talking to the vessel captain via radio/mobile phone, making sure that the vessel will traverse under the bridge. Once the vessel has cleared the Fender piers, and no other vessels need to pass under, the bridge operator turns the NAVIGATIONAL LIGHTS switch to OFF, which turns the vessel traffic lights back to red for both up and down stream.
Time to lower it down.
1. Navigation Lights off.
2. Lower the span, changeover switch to off.

The span lowers to about the 60% point and switches OFF. The INCH push-button needs to be used to lower the bridge in several slow stages before docking. The model will only use one stage, at about the 80% point and the remainder will be lowered, via the INCH button, at half speed.

Once docked, of full down, the LIFT SPAN LOCK OPERABLE lamp turns ON.

Note: The STOP button is only used for emergencies. The power to the span and boat motors will be switched OFF, and a buzzer will be enabled to allow museum staff know that the STOP button was used. This is in case there really is an emergency need to stop the bridge operations.

3. Extend the span locks, switch to off. LOCK (not shown in diagram)
4. Open the off-going traffic gates, switch to off.
5. Open the on-going traffic gates, switch to off.
6. Turn the traffic lights green
7. Once traffic is moving, secure the board by turning the control switch to off.
The "Lift Span Motor" meter is an amp meter to tell how hard the bridge is moving. Without it you have no idea if something is binding until the parts start flying. The last bridge I did, a 4 leaf double bascule, had 8 drive units producing 1.2 million foot pounds each. If something goes wrong that'll
leave a mark. The "Changeover" switch is to select the back-up drive incase someone wasn't paying attention to the Lift Span Motor meter. Another useless tidbit. Drawbridges are overcorrected, if the brakes are released they fall slowly UP due to the too heavy counterweights. Bob H.

The Ammeter could not be used to the model. Instead, I took out the meter movement, and had the needle stuck at 75% full-scale mark, and installed two white LED lights behind the cover. The meter lights up when power is turned on via the CHANGEOVER switch, the first step in operating the bridge.

Bob, you did a good summation of how the bridge works. There are still a few things I did not mention, like when the green and red gate panel lamps turn on and off, and when other lamps turn off also.

[Sparky]

Took the front panel away to see what was involved and what could be serviceable for the model.



Using the iPhone to take photos in awkward positions, I was able to decipher the switch connections.





After all of this, it became clear that much of the wiring needed to be re-routed. So I decided to strip it all down and re-wire it to serve a completely different service to operating a DC model.