[MOC] Moveable railway bridge

[faph]

I have not seen too many railway bridges on this forum, let alone bridges that move!

This MOC is not quite a common type of moveable railway bridge either, it's a double-leaf drawbridge. More common would be a bascule bridge. The difference being that a bascule bridge has it's contraweight either directly below the (rail)road or above it, but then directly attached to the bridge deck. The double-leaf drawbridge has a contraweight attached to a 2nd structure above the road.

The nice thing about this bridge is that it allows me to keep the track very low to the ground. My Lego railway simply lies directly on our flooring.

The contraweight includes a 2 x 6 x 2 weight brick. Not entirely sure how well the bridge is balanced - a real build would have to prove.

 

Edited April 16 by faph
typo

[Murdoch17]

Nice work, I love it! 

[ivanlan9]

Nice little bridge that would be right at home in Amsterdam.

[faph]

There are 2 slight issues with the design though.

1. I had to add an extra stud between the track segments at either end of the bridge. This would obviously cause the track to become "out of grid".

2. Even when spacing the tracks, there is probably 1 part of the bridge track that touches the fixed track. I think a knife might be required to address this :(.

I am not sure if there are better ways to achieve this while making the track as smooth as possible. With the 12V rails that would be simple to achieve of course. But I do want this to connect to 9V track...

[Murdoch17]

@faph I don't think you can do this with anything but unpowered track and battery powered trains. Too many gaps, and you'd need a separate power supply to the bridge itself for 12v or 9v.

[Ropefish]

Oh this is delightful! One idea is you could solder a wire or contacts in some way? So that when the tracks come down they make contact.

[Stereo]

If you brought the gap down to 1/2 stud, and made the pivot point near the top of the rails where they have electric contacts on the sides, you could probably connect 9V at that end of the bridge.  The way tracks interlock means the other end can't be fit any closer together though.  Being 1.5 studs longer than normal straight track instead of 2 studs isn't really an improvement for getting it onto the grid, as well.

 

Though from what I've heard, on a straight section of track, as long as the flanges have a surface to ride on, trains are a bit tough to derail.  They prefer to continue going straight, and will just get back on track after the gap.  So a small gap might run fine and as long as it's less than 6 studs long, 9V motors have enough pickups to keep powering past it.

Edited April 17 by Stereo

[sporadic]

So I'm not really a train guy, so this might be an impractical solution.  I've experimented with using tiles on the side to replace straight track.  The goal of mine was so I could have a working underground cable car, and needed track without spacers.  It seemed to work, but I never did more than a short length and never had any idea how to do curves.  But could you use something like that on one/both sides of the bridge for 7 studs to get it back on grid?

I think this is really cool, btw.

 

[zephyr1934]

 

7 hours ago, faph said:

There are 2 slight issues with the design though.

1. I had to add an extra stud between the track segments at either end of the bridge. This would obviously cause the track to become "out of grid". 

...

2. Even when spacing the tracks, there is probably 1 part of the bridge track that touches the fixed track. I think a knife might be required to address this :(.

As others have said, trains are fine with a short gap, placing the rails one stud apart actually results in almost no gap because the connection point of the rails overlaps. If you are pegging to baseplates it could be a problem though...

 

3 hours ago, sporadic said:

So I'm not really a train guy, so this might be an impractical solution.  I've experimented with using tiles on the side to replace straight track.  The goal of mine was so I could have a working underground cable car, and needed track without spacers.  It seemed to work, but I never did more than a short length and never had any idea how to do curves.  But could you use something like that on one/both sides of the bridge for 7 studs to get it back on grid?

... and this solution works well. I've made brickbuilt track for street running (see below) so you could use brickbuilt track and make the gap that way without getting out of grid

 

[Shiva]

What happens, if the bottom hinge point is higher up?

[faph]

Thanks all. I should have said 9V plastic, as in battery! I meant with a classic rail I could easily align them in grid without a gap. 
 

Potentially I could experiment with tiles on the bridge itself to get myself back on grid. It feels ugly though…

I think if the pivot point is any higher I might get into a collision situation at the other end as the bridge deck’s underside might be too much at an angle when it drops onto the pads. Not sure. 

[faph]

Would this be the best way to use tiles-as-rail on the bridge:

Or are there better ways to mount the tiles?

[Feuer Zug]

Great design. The compact nature makes it perfect for the small distance. The 1/2 stud offset is what I use with the bridge I built. It doesn't seem to have any issues with trains rolling across the gap.

[faph]

Proof of concept with 1/2 stud gap seems to work fine indeed:

[Man with a hat]

Nice bridge. Interesting to see how the final design will look like. The proof of concept look good anyway.

[LEGO Train 12 Volts]

Wow I missed this masterpiece!

Excellent technique and great realism...the solution of the rails using the tiles is perfect!

[faph]

I am now going with this: it gets me back on grid and avoids the collision:

Edited April 18 by faph

[faph]

Plus we have the advantage of staff being able to get into the office in comfort!

I guess if I worry about that level of detail I should move the door to the back of the building as well, so we can actually open the door fully.

The track is actually intended to be slightly inclining/sloping at this point. Just haven't drawn it like that in Studio.

Edited April 19 by faph

[sporadic]

This is coming along really nicely.  Looks great.  I like it a lot.  One minor quibble.  The track tiles currently rest on studs, which is 'illegal'.  Whether that matters or not is, of course, up to you.

[Phil B]

Another quibble is the studs showing on the wedge in the center of the track. There might be trains that have an issue with those studs, you might need to come up with a tiles-only solution to resolve.

[faph]

@sporadic thanks, I didn’t know that. Is there technically not enough space above the studs? It seems to fit quite nicely and Studio collision is also good with it. I could fix it easily but for cheapness I might just keep it as is. 

@Phil B I guess official Lego sets have enough clearance above the track? 

In the proof of concept I had a snot approach but in real life I like studs on top where possible. Our daughter needs to be able to place minifigs anywhere!

Edited April 19 by faph

[faph]

@sporadic I see, the Lego logo on the studs is the problem. I’m happy to follow the “non-standard” technique in this case ;)

[faph]

@Phil B So yes you're absolutely right. A train plow does not have enough clearance for the studs! Thanks for keeping me right here.

[Phil B]

3 minutes ago, faph said:

@Phil B So yes you're absolutely right. A train plow does not have enough clearance for the studs! Thanks for keeping me right here.

 

You're welcome. With regards to the track tiles resting on the logos of the studs below, you could consider putting 4x4 tiles with a single row of studs (part 6179) under the track, that way there is no "illegality".

[faph]

This should be better: