Back to Chronicles To Irasburg's Black
Irasburg's Covered Bridge Lost to Arson
The Paddleford Truss
Some Notes About the Original Bridge Some
Dimensions of the New Bridge Meet The Bridge Man - David
Irasburg's New Covered Bridge Opens to Traffic
The Irasburg Covered Bridge is open at last, connecting the towns of Irasburg and Coventry
over the Black River. Governor Dean cut the ribbon in the early evening, Monday, November 29.
The first person to officially cross the bridge was Roy Ingalls, long time Irasburg Selectman. He
drove his pickup truck the final several feet out of the bridge through the south portal with
Governor Dean as passenger.
With the sturdy timber used in the construction and the liberal
application of fire-proofing chemicals, the new bridge can be expected to stand up well against
time, traffic, and vandals.
All of Vermont's covered bridges are unique and each has
a quirk of its own -- this one is no exception. John Weaver of the VAOT and the replica's
designer pointed out that the original Irasburg Bridge was constructed with a fourteen-panel
truss, the number of counties in the state of Vermont. Vermont, of course, was the fourteenth
state to enter the union. The replica also uses a fourteen-panel truss.
The new bridge was built by Blow and Cote of Morrisville to
replace the Orne covered bridge lost to arson on Halloween, November 1, 1997. The same firm
reconstructed the Henry Bridge in North Bennington, and the Gates Farm Bridge in Cambridge.
Dave Sargent of the Vermont Agency of Transportation is the construction engineer.
The trusses were laid out on the ground and there the
hundreds of diagonal laps were cut across king posts, braces, and chords in the pattern typical of
the Paddleford truss used in the original bridge. Square laps were cut for the doubled upper and
lower chords as well. Those timbers, southern yellow pine, measure* 8.5 x 11 inches, the 15
king posts; 12 x 12, the braces; 10 x 10, and the counter braces; 4 x 8. Also, the counter braces
are lapped into both sides of the truss instead of just one. This is no bridge for horse and buggy--it
appears to be designed for whatever needs to cross over, with a generous margin of safety.
See "Some Dimensions of the New Bridge" below(* Thank
you, Jon Armstrong.)
Carpenters Albert Lauzon of Coventry, Roland Blais of
Newport, and Louie Fagnant of Arlington cut the laps with chainsaws and cleared the cuts with
chisels. The huge timbers were moved into place with the aid of a fork-lift. The prerequisite
"camber" was set by bending it into the chords prior to marking out the laps. When the first truss
was completed, it was raised by crane into a standing position against a set of steel piles erected
for the purpose. When the lifting slings were slacked off, said Fagnant, the truss lost only
one-quarter inch of camber.
Asked how much the truss might weigh, Fagnant, estimating
from the sum of the weights of the timbers, replied that the truss could weigh about 16 tons.
When the second truss was completed, the two trusses were
placed over the river the modern way -- with a crane.
Fagnant noted that he had seen chisels used by an area
carpenter bearing the initials J.D.C. - John D. Colton, the builder of the bridge being replaced, and
probably the builder of the Paddleford bridge off Old Dump Road (now Covered Bridge Road).
One of the antique chisels being used in the bridge restoration carries the initials
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Some Notes on the Dimensions of the Original
Named "Orne Bridge"on the National Register of Historic Places.
Length: 86'; Width (inside clearance): 15 ' 10"; Portal Height: 11' 9";
Capacity: 4.5 Ton.
The Paddleford Truss: king posts - 8x9 (15/truss), braces - 6x8, counter braces -
Deck: deck beams - 9x13, deck sheathing - 2x6 nail laminate, running planks - 3x8.
Roofing: metal, green, standing seam, 12 inch gable-end overhang.
Gable construction: 45 inch overhang each end of bridge supported on corbels; vertical
planking, rounded portal and filets from corbel-ends to eaves, trimmed with white-painted wood
molding; sign - "Strictly No Trucks Allowed Per Order of Selectmen."
Siding: vertical planked; north side planking extends to within 8 feet of eaves, south side
planking to within 22 inches of eaves.
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Some Notes on the Dimensions of the New
This information was provided by Jonathan Armstrong, VTrans Structures and Assistant
Designer of the new bridge:
Top and bottom chords- (2) 8 ½" x 11" Glulam Southern Yellow Pine 16F-VI
Vertical posts (kingposts)- 12" x 12" SYP Dense structural grade 65;
Tension diagonals (counter braces)- double 4"x 8" SYP Dense structural grade 65;
Compression Diagonals (braces-10"x10" SYP Dense structural grade 65;
Floor Beams- 8"x14" SYP Dense structural grade 65;
Floor-5" thick Glulam SYP;
Floor Runners- 3" thick oak (to protect floor);
Between the Floor Runners: 1 ½" Poplar (to protect deck from studded snowmobile
Just about everything else is Spruce (rafters, roof boards, rafter beams,
ridge pole, 8"x8" crossties, 4 ½"x4 ½" cross ties, 4"x4" knee braces, 3"x6" plank
3"x10" end diagonals, side nailers and boarding.
All treenails are white oak (mostly 1 ¼" diameter).
The bridge is designed for 20 ton two axle truck (H20-44).
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Joe Nelson, P.O Box 267, Jericho, VT 05465-0267, firstname.lastname@example.org
Text this page Copyright © 1999, Joseph C. Nelson
Drawing this page Copyright ©, 1999, Joseph C. Nelson
Photographs this page Copyright ©, 1999, Joseph C. Nelson
This file revised 10/26/2006