modern double track railroad truss bridge - 7900 inspired MOC - real world model

[Murdoch17]

This double track train trestle is finally finished! The bridge uses four girder parts from City set 7900 from 2006 that I've had laying around for 18 years without much luck at making a bridge (despite several attempts) - until now!

The bridge is ~30 inches long, and is designed to hang between two tables with the parts under track off the end of the bridge proper serving as feet, holding the bridge level and on the table top.

Looking up track through the centerline of the bridge. There are 16 bricks of space from top of the rail to the roof girders, which means it can take double-stack Maersk container cars with a plate to spare. To pick the bridge up, you can grab anywhere but the roof lattice - those plates aren't reinforced enough to take the weight.

The underside has been reinforced since the initial design stage... It's a lot stronger now, and *should* be able to hang between two tables without breaking while trains run over it. (I've not been able to test this with motorized trains as I don't own any.)

Thoughts, comments, questions? Feedback is appreciated!

EDIT 7/6/24:

Please pardon my messy layout! I've really got nowhere to go with most of this stuff, but nevertheless I just managed to rearrange it around, moving tables and adding my bridge to the mix. The bridge works beautifully and hasn't collapsed yet which I consider a major win for my design skills!

A digital look at what the layout looks like without the stuff in the way.

Edited July 6, 2024 by Murdoch17

[JopieK]

Nice one @Murdoch17. Will you also make it in such a way it can open / go up / go down?

[Murdoch17]

29 minutes ago, JopieK said:

Nice one @Murdoch17. Will you also make it in such a way it can open / go up / go down?

Thanks @JopieK for the compliment and the front-paging! I wish I was smart enough / brave enough to be able to even attempt making it lift up, but I'm not even sure how to begin, so static it will stay.

[Grover]

Looks great!  I like the industrial look, and I appreciate the pictures of the underside where you can see the plate reinforcement.  Does it flex much?  I'm curious how strong it is and how much it flexes.  It's a nicely thin and light structure, and it would be pretty cool if it were rigid so that trains carrying the loads of batteries could pass over without flexing enough to slow the train down through sags etc.

[Murdoch17]

6 hours ago, Grover said:

Looks great!  I like the industrial look, and I appreciate the pictures of the underside where you can see the plate reinforcement.  Does it flex much?  I'm curious how strong it is and how much it flexes.  It's a nicely thin and light structure, and it would be pretty cool if it were rigid so that trains carrying the loads of batteries could pass over without flexing enough to slow the train down through sags etc.

@Grover Thanks! As to your question: I've tried flexing it with my hands, and nothing discernable happens.

[Feuer Zug]

Great bridge design. I like how you expanded the height of the structure with additional technic pieces to allow for the intermodal cars to clear.

[Murdoch17]

31 minutes ago, Feuer Zug said:

Great bridge design. I like how you expanded the height of the structure with additional technic pieces to allow for the intermodal cars to clear.

Thank you @Feuer Zug!

[GI_Jack]

This bridge looks very interesting. It reminds me of the one I used to see when visiting my grandparents. Nice build

[Murdoch17]

3 hours ago, GI_Jack said:

This bridge looks very interesting. It reminds me of the one I used to see when visiting my grandparents. Nice build

Thanks @GI_Jack! Glad you like it!

[Man with a hat]

Wow, I always like a nice bridge. It looks sturdy enough.

[Murdoch17]

4 hours ago, Man with a hat said:

Wow, I always like a nice bridge. It looks sturdy enough.

Thanks for stopping by @Man with a hat, it seems to be sturdy. (I still  haven't been able to test it thoroughly though)

[Shiva]

Nice bridge :)

Direct flick links would be <3

[Murdoch17]

8 minutes ago, Shiva said:

Nice bridge :)

Direct flick links would be <3

Thanks @Shiva. Here is my Flickr stream. The bridge was posted on June 18th, so it isn't too far down the first page.

[Shiva]

Cheers :)

Regarding the bridge. A What If.

If, having it in the style of Elbebrücke Dömitz style? skipping the top part. Instead at top, adding  Technic, Liftarm Thick 1 x 13 on each side, strengthening the girders. Bottom, increasing the number of bottom I-beams with 7 or 8? + either 9 or 13 long liftarms each side, strengthening the girders at bottom? Between the rails, there's, sort of space for an inspection path? 

Instead of going to sleep, I have admired your bridge + checking the potential sidegrades, for 2 hours. Ooops!.

[Murdoch17]

10 hours ago, Shiva said:

Cheers :)

Regarding the bridge. A What If.

If, having it in the style of Elbebrücke Dömitz style? skipping the top part. Instead at top, adding  Technic, Liftarm Thick 1 x 13 on each side, strengthening the girders. Bottom, increasing the number of bottom I-beams with 7 or 8? + either 9 or 13 long liftarms each side, strengthening the girders at bottom? Between the rails, there's, sort of space for an inspection path? 

Instead of going to sleep, I have admired your bridge + checking the potential sidegrades, for 2 hours. Ooops!.

I'm not sure I understand what you are trying to say. The top part on the sides helps it to clear the train cars. Without the extension, it doesn't fit any cars. If I put that extension at the bottom, it doesn't work either.

Thanks for your suggestions @Shiva, but I'm gonna keep it how it is.

[Shiva]

I meant, try without the extension. As in, no height limits, as on the Dömitz bridge.

For the bottom, I meant plates 2 wide and whatever length needed, below the railroad ties and parallell to those.

[Murdoch17]

Main post edited with the following info as of 7/6/24:

Please pardon my messy layout! I've really got nowhere to go with most of this stuff, but nevertheless I just managed to rearrange it around, moving tables and adding my bridge to the mix. The bridge works beautifully and hasn't collapsed yet which I consider a major win for my design skills!

A digital look at what the layout looks like without the stuff in the way.

[Shiva]

Thumbs up :)

Ever tested how the stability is without the plates on top? aka, the extension.

 

[Murdoch17]

5 minutes ago, Shiva said:

Thumbs up :)

Ever tested how the stability is without the plates on top? aka, the extension.

 

@Shiva The roof keeps everything square / trim and in line with the base. If I remove it, the sides get wobbly which I'm trying to avoid. Thanks for the suggestion, though.

[Shiva]

Cheers for the info.

[JHS_NL]

Great bridge! Nice and sturdy.

[Murdoch17]

4 hours ago, JHS_NL said:

Great bridge! Nice and sturdy.

Thanks @JHS_NL!

[trucks3]

NOICE MB btw I would put some wood/metal rods under that

[Murdoch17]

1 hour ago, trucks3 said:

NOICE MB btw I would put some wood/metal rods under that

Thanks for the suggestion @trucks3, but it works fine as is... LEGO is stronger than you would think!

[trucks3]

22 hours ago, Murdoch17 said:

Thanks for the suggestion @trucks3, but it works fine as is... LEGO is stronger than you would think!

i know right but my og semi trailer bent a lot. i will do instrux on that soon