Back to First Page.Pulp Mill Bridge Closed For repairs. Again.
|Photos by Joe Nelson, June 28,
June 24, 2002 - Joe, I stopped by the Pulp Mill Bridge this noon to say hi. Paul Ide
gave me a brief synopsis of the structural problems with the bridge. As I understand it (aside from
rot etc. (how much, I don't know) the issues are because of the improper "fixes" of bottom chords
in past "repair" attempts. The tension bottom chords are sistered and improperly done.
I took a few photos at a site cut out of the deck which
will show a huge plate bolted over one of these joints by about 7 or 8 bolts each. Paul says the
holes bored to accommodate the bolts were drilled way too large, probably to allow for ease of
bolt installation. The sistered joint I could see had slipped several inches. Paul says there are eight,
maybe ten, of these plated sistered bottom chord joints and the entire mess must be corrected--the
dollars not being there and, of course, piece-meal work only adds to the cost of repair.
The arch only adds to the dead load, said Paul Ide:
when the two piers were installed it should have been removed and the bridge left as three
multiple kingpost spans.
Boy, is traffic a mess in Middlebury with one
bridge in use!
Jun 30, 2002 - Hi Joe, we continue to undo the results of a bad repair in the 1980's.
The bridge itself, although one of the oldest in the state and justly famous, has been in trouble
since the day it was built.
Examination of the structure shows that the Pulp Mill
Bridge was originally a single span of nearly 200 ft., probably based upon the numerous double
barreled Burr variants around at the time. A crucial mistake was made in its original construction
however when the posts, which both act in tension and accept a horizontal thrust from the main
braces, were not shouldered into the chords, but merely affixed with a single square bolt. The load
on the braces quickly began to break these posts across the bolts leading the bridge to sag and to
drastic solutions such as the addition of arches and the subdivision of the bridge into three spans,
with the necessary reversal of half the bracing.
We are working on the middle truss of the north span,
rebuilding the chord, staggering joints, adding shear blocks and shouldering and check braces et.
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This file posted June 30, 2002, revised July 17, 2002