Thursday, August 1, 2013

Rt 7 Bridge--Day 2

July 30, 2013

Today was about getting the previously assembled beams across the stream and fastened in place. 
Sill work, beams in background

Dave and Jim setting sills
We finished up the sills for the bridge to rest on and on the beams, laid out and attached the joist hangers for the internal bracing.

Denis finishes up sill bearing plates.

One at a time, each 500lb beam was then slid from the assembly area and pivoted to align with the sills before being sent across the stream. 
Dragging a beam into position for launching.
This was probably the most difficult part of the day, as the ground was not particularly even, and the 36ft pieces were heavy and cumbersome.  Next time, we'll bring some rollers to ease this process.

To keep the beams upright and horizontal on their way to the far bank, we installed a piece of 1/4" wire rope across the stream to carry the front end.  This wire was 75 ft long, attached to a tree on the south side, and to a post we installed in the corn field as the anchor on the north side.   To support the 250lb end of the beam in the center of such a long span, this wire needed to be very tight.  We used two 1/2" diameter turnbuckles to tension the wire until the post began to shift slightly in the ground.  A bracket was attached to the front of the beam to hold a pulley that traveled along the wire.

Beam #1
Beam #2 starts the journey
With most of the team lifting and pushing from the north side, the beam was slid over the sill and out over the stream. 

As the beam approached the south bank, two people lifted and pulled the beam up and over the sill.

Once all three beams were across, they were set in their final locations and screwed to the sills with timber screws.

First beam landed
All 3 beams in place and ready for planks
On our next (and hopefully final) day on the project, we'll work our way out along the three beams installing blocking and deck planks as we go.  Then a railing will be set in place and the old bridge taken apart and removed from the site.

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