White Arched Bridge


White Arched Bridge

I made this bridge for a TexLUG show and train layout in March 2004. The bridge design was fairly simple, so it didn't take a lot of time to construct.

The bridge carried dual train tracks. We ran long trains over it during the show and the bridge performed well.



click for sketch


Info

The bridge was sized to fit exactly on 9 regular baseplates (32 x 32 studs each).

The pattern of the arch is simple- each of the 11 segments are pinned together, and the geometry of the holes (i.e. hole spacing) is identical. 6 of the sections are 2 studs wider than the other 5 sections. This enables them to be interlocked and pinned together (e.g. the smaller ones slot into the larger ones).

The deck is composed of parallel sets of LEGO train track. There are support hangers at each joint (every 16 studs), and the tracks are also linked together with plates.

The deck is placed under tension by the arch because it wants to spread outwards. Gravity pulls the arch downwards, and therefore the ends want to spread out.

I suspended the deck by simply "eye-balling" it. Each section of string was adjusted until the deck appeared somewhat level.



Specs

288 studs total length (~7.50 ft., 2.29 m)
268 studs free span (unsupported length) (6.98 ft., 2.13 m)
32 studs total width
arch made of 11 pinned segments, pinned holes geometrically identical per section
Double train track suspended from arch
Track spaced with 8-studs clearance between them
Arch wants to spread outwards, but track is placed under tension thus fixing the arch shape
Bridge is strong and stiff- it can be easily picked up with two hands and moved

Thomas J. Avery 2004