West Townshend Stone Arch Bridge: Week 4

West Townshend Stone Arch Bridge: Week 4

As a wise person once said: "You can't make an omelet without breaking a few eggs", and THIS is the part of the renovation process where more than eggs get broken...welcome to Demolition Week!

Unlike the devastation that is usually associated with the word "demolition", this is a very precision oriented operation. Every step needs to be taken in a manner that will preserve the stone arch structure from over which all of the material is to be removed. All of the different materials taken out will need to be carefully separated as they are removed for either reuse or recycling.

The first step is to break apart and remove the existing asphalt. As you can see in the vignette video to the right, two large excavators work in tandem to achieve that goal.

(Play the video to see the demolition begin!)

Check out the time-lapse YouTube video below to see the work in progress!

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To expedite the removal of the asphalt, and to maintain the integrity of the basic material separation, and excavator has been retrofitted with a jib boom (as seen in the picture to the left), chain sling, and trow bucket with witch to swing the material away from the bridge surface as opposed to dragging it along the surface with a standard digging bucket increasing the risk of cross-contamination.

After the chunks of asphalt were successfully removed and segregated into a pile of its own, the next step was to remove the infill material (this is what makes up the bulk of the bridge material between the arch ring and the asphalt roadway material).

As illustrated in the picture below, in the particular case of this bridge, the infill material is basic crushed gravel. What makes that interesting is...that was not the common way of doing things at the time the bridge was initially constructed in 1910 by James Ottis Follet. During that time period it was a generally accepted practice to use rocks to create the infill.

Once the removal of the infill is completed (as shown in the picture to the right), the next order of business is to remove the parapets, in this case the large concrete sections on both sides of the infill. The orange paint lines denote where the saw cuts will be made to divide the concrete into more manageable blocks.

With the saw cuts successfully made, the next step is to hoist the more manageable, yet still ungainly concrete blocks up and off of the bridge form. As demonstrated in the picture below, the team let the big machines do that lifting. By use of well placed chains, the excavators are able to swing the blocks around and move them to the staging area.

Encased in the concrete parapets, the team found the original steel guardrails...check out the YouTube Video above to see more about that neat little side bar.

After all of the concrete parapets are safely staged, and the rest of the infill has been hoed out and stockpiled, the last step is to remove the spandrel walls (as pictured to the right), and...VIOLA! The arch ring is now exposed and can be securely worked on. Check out the pictures and vignette videos below view more of the process and to see the progress unfold!

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More Photos of the Work In Progress!

Check Out These Vignette Videos of the Work In Progress!