Cribbage anyone ?

While waiting for Alex to return from vacation I kept myself busy with a little work at the bridge site.

This bridge will require assembling on site and so cribs of the correct height and in the proper location (one at each chord butt joint) will be needed. In the picture above you can see the abutments and the cribs for the bottom chord. The local highway shop had a good supply of 6x8 guard rail posts and blocks that they let us borrow for this work.

Here you can see the cribs built and I have placed some 4x4's on top to simulate the first layer of chords that will be placed on them.

From this portal view you can see how the bridge truss will be assembled and then raised to vertical. This process must then be repeated on the other site for the second truss.

I can now relate with some tiny amount of personal experience what Milton Graton did in 1968 when he built the 140' Union Street Bridge in Woodstock, Vermont. The pictures in his book on  pages 98 - 101 are beyond belief! Surly if you are interested in this type of thing by all means get a copy of his book, The Last of the Covered Bridge Builders. The engineering and design of moving this bridge by hand over the river and into place is the stuff of legends! Truly Milton was a master of his craft.

Puzzler - How will loading and unloading of the truss parts need to be managed and what difference will it make?

Tech Vocab - Crib - Capstan - Needles - Rolls - Shoes - Rocker Blocks - Abutment - Track