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V.A.O.T. Historic Bridge Committee
Historic Covered Bridge Committee Notes of Field Assessment on May 6, 2001
CAMBRIDGE GRIST MILL (CANYON) BRIDGE
Met with representatives from the Town of Cambridge, a representative of the Vermont
Covered Bridge Society and Tim Grant of McFarland-Johnson, Inc., consultant for VTrans.
Committee members in attendance were: Bob McCullough, Sue Scribner, Nancy Boone, Eric
Gilbertson and Scott Gurley (for Scott Newman). Also in attendance was Gary Rogers,
Structures Project Manager.
The Town's concerns focused on the need to safely transport cars and light trucks; they
indicated they would be willing to post the bridge for 6,000 lbs. Mr. Grant provided a "List of
Damaged Items" with recommended actions as well as plan views of the structure. In general, it
was recommended that members either be repaired or replaced in kind. He also provided a "tour"
of the bridge, pointing out many of the damaged items. In addition to the list provided, Mr. Grant
recommended that the deck be replaced and the approaches paved. Mr. Grant's structural analysis
led him to conclude that the bridge is only capable of carrying 5,000 lbs., controlled by the bottom
chord. The Town requested the anticipated time frame for rehabilitation; Mr. Rogers indicated
that current plans are for the project to be bid for the 2003-construction season. The Town
expressed concern that some interim repairs might be needed. It was agreed that Mr. Grant would
prepare a listing of the items that he feels are necessary to be repaired in the interim; he will
forward this to Mr. Rogers who will forward it to the Town.
Overall, the committee was impressed with the current condition of the structure. Its
recommended preservation treatment is Category A -Special Use on Roads and recommended
treatments fell within Treatments 1 and 2 of the draft Preservation Plan. Several committee
members expressed skepticism with the results of the structural analysis; the bridge has been
carrying higher loads and shows very little evidence of distress. There was agreement that the
"List of Damaged Items" and recommended actions appear reasonable with the exception that
several members did not feel that the east abutment requires addition of mortar, rather it was
recommended that a stone mason re-chink the abutment. Mr. Rogers requested that Mr. Grant
reevaluate the lower inside (downstream) bottom chord at its mid-span (5` vertical). Some
committee members also indicated that they did not feel it would be necessary to pave the
approaches as it was felt that a substantial distance would need to be paved to be effective and
prevent debris from being tracked onto the structure. Finally, it is recommended that steel-backed
timber guardrail be used on the approaches.
10 Ferry Street, Unit 11 Suite 210
Concord, New Hampshire 03301
JOB: CAMBRIDGE 15491.05|
BY: TLGrant DATE: 06/0412001"
LIST OF DAMAGED ITEMS
Remove Hanging Beams
missing fl beam bearing blocks
arch end at abut #1, upstream
4th stringer, 6' past midspan
vertical scarf bolt
3rd stringer @ 13th fl beam
7th vertical from Abut 2,
U-bolt at Abut #2, upstream
5th diag. from Abut, upstream
roof "tie" beam near center
last diag. l Abut 2, downstream
voids & broken
replace with enameled standing seam metal
patch, fill, rebuild
install new beam guard rail
Apply CRESTLINE fire resistant paint to interior framing
Joe Nelson, P.O Box 267, Jericho, VT 05465-0267, firstname.lastname@example.org
No part of this web site may be reproduced without the written permission of Joseph C.
This file posted February 13, 2002