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file:///X|/Special%20Collections/purgatory/Phi%20Mu/Gibbe,%20Lewis/blueprint.txt[4/15/2011 11:28:27 AM]
TEE HISTORY AND CONSTRUCTION
OF
PAINT BRANCH GORGE BRIDGE,
MONTGOMERY COUNTY, MARYLAND.
LEWIS T. GIBBS
MAY 3, 1935
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SUliMAKY
Columbia Pike "between Whiteoak and Burtonsville crosses
a deep, wide ravine at the bottom of which runs Paint Branch.
The "bridge across this point of the stream is called Paint Branch
Gorge Bridge "because of the nature of the stream "bed and ravine.
The gorge is approximately two hundred feet wide and forty- fire
feet deep. Prior to 1920, Columbia Pike was a county road, and
the first bridges to span the gorge were built by Montgomery
county.
There have been four bridges across this part of .faint
Branch, jj'irst, a wooden truss bridge was built tdate of con-
struction unknown J j this was replaced in 1907 by an iron girder
bridge on the same piers, in 1912 a reinforced concrete arch
bridge was constructed thirty-fire feet upstream, which marvel of
civil engineering carried America^ fast-growing traffic until 1930,
when the Maryland state Roads Commission decided that the bridge
must be widened. This was done, and since that time a wide, con-
crete arch bridge gracefully spans picturesque Paint Branch Gorge.
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ORIGINAL jtftlJXUJ
The first bridge across the gorge was a wooden truss
bridge. Its foundations consisted, as may be seen in the sketch
and in several of the photos, of two abutments and a center pier.
Four and one-half feet concrete retaining walls, filled In behind
with earth and granite, made up the abutments. The center pier
was simply a granite rock wall.
This structure was finally considered unsafe in 1907, when
the old wooden truss was removed, and the height of the abutments
and pier was increased three feet by caps of reinforced concrete.
This concrete still appears in sound condition. At the top of tne
center pier, the mortar looks much better than at the bottom, wnioh
is crumbling. The top of the pier must have been strengthened when
the concrete caps were put on. An iron girder bridge was then
erected. The engineers who designed this bridge apparently didn't
look far enough ahead, for as time went on, heavier loads were
applied, and in 1912 a new bridge was considered necessary. Only
the abutments and center pier of the original structure remain, and
these are gradually becoming overgrown with bushes and trees.
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ORIGINAL BRIDGE, FROM TOP OF HEW
VIEW TOWARDS BURTOKSVI1LE
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191S BRIDGE
A Luten Arch bridge was "built in 19 IS "by the juuten
Engineering Company, Indianapolis, Indiana, This was "built thirty-
feet north of the original structure, 'x'he road level is approxi-
mately twenty- five feet ahove the old. This "bridge, narrow as it
was, constituted a great Improvement over the original one.
VIEW LOOKING UPSTREAM
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WIBENED BRIDGE
In 19 SO Columbia Ptfce became a state road, and the
Commission was authorized in 1930 to widen the original 1912
Luten Arch Bridge to twenty- seven feet. A "bid was accepted
from the I. D. Claiborne Contracting Company for $16,137.50.
Mr. S. S. Steinberg, of the Commission, inspected the exist-
ing bridge and submitted his report.
He stated that the foundations had been laid on large
boulders chipped flat. The concrete in the piers was in dubious
condition in parts of the surface, though holes for dowels showed
the interior (which contained some one-man stone J to be sound.
Apparently the piers had been poured from the tops of the forms
and piled up, as shown in the sketch. Run-of-bank aggregates,
containing much fine, inert matter,
had been used in the concrete,
laitance resulted, causing several
unsound places in the concrete.
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The report continued to say that the rest of the "bridge,
abutments, arches, footings were in satisfactory condition. The
grains of the wood from the forms still showed in most of the
concrete. Mr. Steinberg recommended that a 9" Jacket of concrete
about the existing pier would take care of their trouble. This
was later changed to 18".
There was much vibration on the bridge, for cars coming down
the hill from Whiteoak would Jar it. It was decided that "by widen-
ing the existing bridge the structure would be stiffened sufficiently
to take care of any vibration.
.Plans were then drawn up by the State Roads uommission
under the direction of Mr. w. 0. Hopkins, Dridge engineer, .Baltimore,
Maryland. Construction started July 5, 1930. Mr. Gus Mencken,
brother of H. L. Mencken, noted writer and critic, was superin-
tendent of the construction work, representing the T. D. Claiborne
Company. Mr. H. D. Williar, Jr. was chief engineer; Mr. W. C.
Hopkins was bridge engineer; Mr. E. P. Owings, a graduate of the
University of Maryland, was state inspector on the job.
First, the existing piers were encased witn an IS" Jacket
of concrete; one inch round rods with a washer and nut on each end
were placed at five feet centers both ways, a new coping was Ouilt
on the existing downstrea m rail, and a new curbing pu t in. une-
half inch sguare rods were used to bind these to the existing concrete
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The upstream rail, which of course was to be removed, was left
on until last, and only chunks knocked out to allow for the
pouring of concrete. Tnis particular job was made easier by the
existence of the original bridge from whicn rorms could be built,
concrete poured, and general work executed.
The piers and abutments were poured first down reverse
chutes as shown in photograph 1* All the concrete was measured
by volume proportions in vrtieel barrows— a practice then allowed
but now practically absolete, concrete was mixed in a one-bag
mixer and carried to the chutes in two-wheel Georgia buggies.
One of these may be seen in snapshot 2»
At the base of the pier near the uurtonsvilie side, tnere
was a great boulder, 2o dynamite this would endanger the exist-
ing pier, to chip it flat would involve much trouble and expense,
so it was covere d with a block of concrete which is not exactly
in ha rmony with the shape of the pier { photo 3 J but allowed the
new pier to be "built on it, itixc optional care was taken in tne
placement of the long three- quarter inch round rods <a 12" c-c
which extended a quarter length ot the arch and far down into tne
pier.
The plans show the size of the abutments "if rook is not
encountered". Rock, was encountered, however; sott on the Whiteoak
side, and hard on the iiurtonsvilie side, but strong enough footing
1 . CHJTES
2. APPARATUS, MATERIALS
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for the abutments, Revisions of tne plans for tne wings were
made in tne field. Tne plans show the upstream wings witn the
note, "lengtn and direction of wing is tentative; 3hali be built
as directed to suit field conditions", Tnese conditions called
for an angle more approaening tne perpendicular on the whiteoale
side, and Just about perpendicular on the ±iurtonsviile side,
After the piers and abutments were completed, the scaf-
folding was built up, and forms placed for tne arcnes. The forms
were required to exactly fit tne curvature of tnis particular type
of luten arch, so they were "built in an open field near the joo
in the following manner:
A center is picked, from which an arc with a radius of 54 «
11" is swung for a distance of 10 »S" on one side, say the left,
and 12*2" on the other, the right. Along tne radii to these points
new centers are placed with new radii, 44»0» on tne left,' and 46'9»
on the right, swung for distances of 82*6" and 32' 5» respectively
from the original middle point of the arch. Finally, centers are
Placed on the radii to these points and short arcs with radii of
4' are swung to complete the arch. This description fits the end
arches whose end elevations ere not the same. The center arch has
different values for radii. tat *as , oth ends Qn ^ _ ^^
are laid^ "" ^ " "" "* * ^ * *» ~>oards
are laid down and cut to fit it thus:
■I
3. PIER ON BURTONSVILLE SIDE
4. STEEL IE THE ARCH
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These "boards ran lengthwise with the span, and supported 6" toe
boards running perpendicular to the span. Steel was then care-
fully laid {photo 4), and finally the concrete was poured.
In the first concrete bridge, no allowance was made for
drainage, so in the new arches, 4" round tile drains were set
to take care of rainwater, etc.
The one -half square bars at 2 T centers measured along
the intrados were bent up to go in the inside face of the spandrels.
Expansion joints with §" felt were plfced at approximately third
points of the spans in the rail, and two (4* apart) were intro-
duced down to the arch ring above the pi era. Mo tar paper was per-
mitted. Ties, as seen in the plans, of two types, A and B, were
used to hold the new arches to the old. After the arches and span-
drels were formed and set, the old upstream rail was removed, and
the arches filled with neighboring rock and earth. The road was
then built on this.
Construction was entirely completed just before Thanksgiving f
1920; the total cost of all v;ork was $16, 9 £6. 34; $788.84 above the
original bid, which was close enough to be satisfactory.
Two bronze plates, one in each rail, may be seen with this
inscription:
PAINT BRANCH GORGE BRIDGE
WIDENED IN 1930 BY STATE ROADS COMMISSION
G. Clinton tJhl - Chairman
Howard Bruce
John K. Shaw
H. D. Wllliar _ chief Engineer
W. C. Hopkins - Bridge Engineer
VIEW TOWARD WHITEQAK
VIEW OF ROADWAY
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BIBLIOGRAPEY
Information was gathered for this thesis from the follow-
ing sources:
Original Bridge - Harry B. Shaw and Raymond Stevens,
County Engineers, Silver Spring, Md.
Harry L. Miller, Resident near "bridge,
191 £ Bridge - Attempted to oh tain information from
Luten Engineering Company, but letter
unanswered. L.B.Johnson, State Roads
Commission, Baltimore, Md.
Widened Bridge - i,B. Johnson, State Roads Commission,
Baltimore, Md.
E. P. Owlngs, State Roads Commission.
Hyattsville, Md.
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THE F0TUEE
Before the Claiborne Company undertook this job, they
agitated the Commission about constructing an entirely new
bridge instead of merely widening the old one. The State
Planning Commission might have done wisely in heeding this
suggestion, for the Columbia Pike is under consideration for
carrying a new east coast boulevard from Washington to points
north of Baltimore. The present six-lane Washington- Baltimore
boulevard is insufficient to carry the very heavy traffic it
now does, and may expect to carry, so a new route is being care-
fully considered. If this new route runs across Paint Branch
Gorge, the interesting history of bridges at this point will be
made more interesting by perhaps a more ingeneous and a more
beautiful type of bridge.