Greenwood Underpass

[e-paw]

I like that I beam I just might order some for my lift bridge.

[mountaingoatgreg]

Some more progress....

just more mock ups nothing is permanent

[JohnyBotto]

Hey Greg, It's looking very good. I like the green you mixed up for the beam, very accurate! Any tips on your paint blend?

[mountaingoatgreg]

John

The green is a secret blend....

It is Reading Green and NYC Jade green mixed I am not really sure of the exact blend but it is probably 75% Reading 25% NYC
I will need to lighten when I weather it but I am pretty happy with it so far.

[Gary S]

I like the green footings under the H columns. Scratchbuilt?

[mountaingoatgreg]

The feet and metal details are all from SS Ltd



Here is a close up of the columns and bracing.

[Gary S]

Those are some cool little pieces. I've never seen them before. They do add interest to the model.

[mountaingoatgreg]

Progress continues at a snail pace....

Only Two more left to start....

[Ralph]

Lookin' GOOD Greg!!!!
Ralph

[ocalicreek]

Snail's pace is better than a snoozing hare (while the tortoise crawls by...). Ah. Sleep sounds good...

I like the green color, and the careful attention to bridge 'parts', such as shoes, braces, etc. Has a good industrial structure look to it.

Galen

[Mr Fixit]

Hi Greg;

The horizontal cross beam between the vertical I beams do not appear to be subsantial enough to support the lengthwise I beams. By my reckoning you should have used a section of the lengthwise I beam material as a cross beam with end plates welded to the ends to facilitate bolting to the vertical I beams and with a thick shear plate welded underneath.

The loads of the outer I beams would be transferred to the mid point columns, but I do not like the look of the current crossbeams and their ability to carry the load sideways to the columns.

If on the otherhand you have simply copied what the prototype bridge was made of then well and good but it still appears to be undersized, but hey Im no engineer.

Mark

[mountaingoatgreg]

Thanks guys.


Mark: I know wgat you mean by looking undersized and I still have some parts to the center support before it is done. Here are pictures of the actual thing and my model.

[Gary S]

Mark, looking at the prototype photo, it appears that Greg is right on target. I can't disagree with your assessment, but the engineers that designed the bridge must have known what they were doing!

[Mr Fixit]

Ah hah, not so fast people. I was about to admit I was wrong until I looked at the photo closely.

If you carefully look at the inverted T beam, you cant actually see a top edge to it because it continues all the way up as a much larger depth beam than the long beams. So it now appears to me that the long beams butt into the deeper central support cross beam. This would also explain why the vertical I beams continue up past the bottom of the inverted T, to provide plenty of support for the beam under dynamic loads as trains cross. If you look at the inside edge of the vertical I beam on the left you will notice that there is a vertical plate and that this appears to continue across and fills in between all the other beams.

I also noticed that there are cross brace sections at what appears to be 1/3 of the span locations, whose purpose is to prevent the lateral beams from toppling sideways under load.

I will concede that it is difficult to determine what exactly is going on under the bridge given that the photo lacks sharpness due to lighting and the colour of the beams and years of dirt and grime. Perhaps a fresh photo using a good strong flash, aimed at the area in question might be in order.

The bridge itself is fairly old as it is made up of rivetted sections to make the various shapes, and as such I would estimate that it is a pre WW2 era bridge, possibly pre WW1.

I hope that this all helps with your excellent bridge building efforts.

Mark

[mountaingoatgreg]

Mark,

Hey that makes sense, I figured there was some kind of support inside the bridge to hold the pieces together but was not sure what to do. It makes since that it is a T beam, I had not even thoight of that. I made quick work of dissasembly and will have the new improved version soon.

By the way the underpass was built in 1919.