Unique Covered Bridge in Delaware County

Unique Covered Bridge in Delaware County (p. 1)

Unique Covered Bridge in Delaware County

By

David A. Simmons Ohio Historical Society


How do specific bridge designs be-

come popular? During the nineteenth

century, much as today, promotional

literature and sales personnel were

important influences in encouraging

contractors and public officials to use

a specific design or product. The

Chambers Road Covered Bridge, Del-

aware County's only remaining wood-

en truss, owes its design to neither

and may, in fact, be unique for its role

in the history of Ohio bridge con-

struction.

The builder of the Chambers Road

bridge was Everett S. Sherman, who

was born in 1831 to a bridge-building

family in Delaware County. The two-

story frame house built for his father,

David T. Sherman, still stands in the

tiny community of Berkshire, where

recent renovations uncovered the

massive framing -enormous even by

nineteenth-century standards-of a

rear wing built in the mid 1850's. Like

modern contractors, the Shermans

had incorporated leftover bridge ma-

terials into their new residential addi-

tion. The first known work to have

been done by Everett Sherman alone

was the erection of a bridge at

Sunbury in 1867. The Howe truss

system, whose heavy wooden diago-

nals and vertical iron rods were a

familiar sight on American railroads

in the middle of the century, was used

by Sherman in the 1870's. After mov-

ing to a farm on the outskirts of

Galena in the early 1870's, he re-

ceived a patent for a simple bridge

intended for small stream crossings

on rural highways, It incorporated

wooden beams and iron rods, a struc-

tural type known at the time as "a

combination bridge."


[photo: Delaware County's last covered bridge, the Chambers Road Cov-

ered Bridge, was built in 1883 and named for the nearby Chambers

family homestead seen here in the right rear.]


The Chambers Road Covered

Bridge combines wood and iron in a

system patented in 1846 by Horace

Childs, a prominent New Hampshire

railroad bridge builder. A Childs truss

had diagonal wooden braces in com-

pression that were crossed by diago-

nal iron rods, or "counterbraces."

Nuts on these rods held the braces

against the top and bottom chords-

a vital maintenance consideration with

wooden structures susceptible to

shrinkage - and could also be tight-

ened to add camber to the structure.


[photo: Based on a rare patent devised in 1846 by a new England railroad

bridge builder, the Chambers Road bridge has wooden diagonal

members in compression which are crossed by iron rod tension

members.]


[photo: Delaware County forces, under the direction of County engineer

Fred Stults, renovated the bridge in time for its one-hundredth

birthday. New concrete abutments and a concrete pier were in-

stalled to support a group of concealed steel I-beams that actually

carry the loads across Big Walnut Creek. New siding and roof were

were also added to protect the old historic trusses.]


Historians have long puzzled over

Sherman's use of the Childs truss in

the late nineteenth century when it

was already an antiquated structural

system that apparently never saw

much use even by its own New En-

gland designer. Assumptions were

made, now known to have been

wrong, that Sherman,like Childs, was

a native of New Hampshire and must

have learned of this obscure truss

from the older builder himself.

The real reason, I believe, is much

simpler: Sherman had read about it.

In October 1882, a Washington, D.C.

patent attorney began a series of illus-

trated articles in Engineering News on

truss bridge patents whose period of

protection had elapsed, and which

Ohio County Engineers News

Unique Covered Bridge in Delaware County (p. 2)

Unique Covered Bridge
(Continued from Page 10)

were then "public property." The

twenty-nine part series began with

Theodore Burr's 1817 patent and

ended with a suspension truss dating

to 1866 whose patent expired in De-

cember 1883. The December 16,

1882, installment included a descrip-

tion and drawing of the "Childs

Bridge." Sherman, already conversant

in the use of wooden and iron con-

struction, apparently read the article

and resolved to try the system with his

next bridge contract. The Chambers

Road Covered Bridge, using an ex-

pired patent for which no royalties

were owed, was built by Sherman the

following year.

Sherman did more than simply re-

vive a defunct bridge truss; he im-

proved it. In 1886 he moved to Eaton

at the invitation of the Preble County

Engineer, who was also a native of

Delaware County, to assist in rebuild-

ing the bridges recently destroyed in a

"cyclone." The Childs design came

from the empirical age of craftsman

who built without the benefit of scien-

tific truss analysis, and the original

specifications called for braces of uni-

form size. Sherman's Preble County

bridges (only six of his original fifteen

remain) were built with diagonal com-

pression members, the dimensions of

which increased toward the ends of

the truss to accommodate the greater

load carried by each-evidence of

Sherman's efforts to mathematically

proportion the components of his

bridges.

No other Childs trusses are known

to have been built anywhere in the

nation except for Sherman's Ohio

bridges. The Chambers Road Cov-

ered Bridge, representing Sherman's

initial use of the Childs truss and

closely following the original design

features, is thus an important trend-

setter in Ohio and national engineer-

ing history.

The author would like to acknowledge

his debt to the research on Sherman done by

Miriam Wood, historian of the Southern

Ohio Covered Bridge Association.