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Full text of "The history and construction of Paint Branch Gorge Bridge, Montgomery County, Maryland."

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file:///X|/Special%20Collections/purgatory/Phi%20Mu/Gibbe,%20Lewis/blueprint.txt[4/15/2011 11:28:27 AM] 



MAY 3, 1935 



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 

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. 


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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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. 




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. 





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 


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 

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 




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: 





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 


G. Clinton tJhl - Chairman 
Howard Bruce 
John K. Shaw 

H. D. Wllliar _ chief Engineer 
W. C. Hopkins - Bridge Engineer 





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. 


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.