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IN vaaHlKSTOK, D. C. 

The Calvert Street Bridge, crossiiag Hock Creek in Y/ashington, D.C,, 
was built In 1891 "by the Sdgsmore BriOge Co. » at a cost of Q70»000.00. It 
was transferred to the Commissioners of the Jistrict of Columhia on July £0, 
1891( b^ the -iock Creek hallway Co., for whom the bridge was built. Its 
history is a lesson in maintenance to the engineer. V.Tien constructed, it 
was an iron trestle, 750 ft. Ions s^d havin;;; a roadway of 40 ft, in 1912 
the roadv/ay was reduced to 26 ft. A new deck was installed in 1922 with 
steel joists, laminated floor, and asphalt covering. Traffic giiards were 
installed in 1926. 

Proposals were made for a new bridge as early as 1914, Finally, 
In 1934, the Old bridge was moved 80 ft. south to a nev; site; so that the 
structure CD-old be used as c detoiir for traffic during the construction of 
a new bridge on site of the old. The new bridge now more than 40;fe, is to be 
a 3-s 'an reinforced concrete arch structure, faced witli Indiana Limestone, 
having .'i total width of 84 ft. Dae to have the bridge finished by October 
1935, the John "I, Cow^e^ Co was avrarded the contract, on submitting a bid 
of ;^928,724.00, 


The history and construction of the Calvert Street Bridge, 
spanning Hocfe Creek, in V/ashinston, il. C, is not only of interest to 
those watching the expansion and development of the city of Washington, 
"but also to the engineer. 


Rock Creek forms a natural barrier between V/ashington proper and 
'vfeat is now known as the tipper Connecticut Avenue ejection and Chevy Chase. 
There were few bridges spanning Hook Creek at other sites before the con- 
struction of the Calvert ^street Bridge. Three of these bridges were built 
due to the corporation of './ashington and Gfeorgetown on line of Pennsylvania 
Avenira, ML Street, and P Street. Built on line of V/oodley Lane was another 
structure spanning the creek, and was the only one near vAiat is now the 
present site of the Calvert litreet Sridge. The Rock Creek Railway Cocpany's 
cars ran from wliat is novi the west end of the bridge to Chevy Chase and 
itensington, i.^ryland. The Company realized the need of a railroad bridge 
across Rock Creek. J>ue to the great depth of the vedley through vi^ich the 
creek runs, the accessibility of the railway terminal from Washington proper 
over the existing V/oodley Lane Bridge, was difficult* The Ii^ailway uompany 
thought, by bringing their cars into Washington proper, business would be 
greatly increased; therefore, in 1691 the Edgemore Bridge Company of 
Wilmington, Delaware built the Old Calvert Street Bridge for the Rock Creek 
Railway Company. 


Fig. 1 is a picture of 
the bridge as it stands toda^, taken 
from the south side, looking west, 


The "bridge built at a 
cost of :#70,000.00; as shovvn in 
fig. 2, was a decic- truss trestle, 
750 ft. loiag, with two trusses 
spaced 25 ft., c, to c, supported 
by five tovrers and two abutments. 
JSach tower consisted of four laced 
steel colirmis with lattice bracing 
between the col\Eans. On the two 
trusses rested transverse floor 

beams which supported a 40 ft, tiinber-deck roadwaj^, including two street car 
tracks, and two cantilever sidewalks of 5 ft. each. Ihe height of the 
structure was 125 ft. bpan lengths were V5, 90, and 135 ft. it was opened 
for pedestrian, vehicular, and street car traffic. 

Although the bridge was conrpleted early in 1891, the Hock Creek 
Railway Con:5)any transferred it to the Commissioner of the iJiiitrict of Col- 
umbia on July 20, 1891, and the Company itself was dissolved by the Capital 
Traction Company. It is believed that the construction of the bridge caused 
the bankruptcy of the Hock Creek Railway Company, although there are no 
records showing this. 

Fig. 1 


, ^ , -a SSQ.4J 

Ibutment L; gQ, . -t^-JO ^ 

150 ' 


Fig. 2 


The history of Calvert street Bridge is in itself a lesson in the 
cost of laaintenanoe. Although the cost of construction was only $70,000.00, 
the cost of i;aintenance vra.s approxinately ^UStOOO-OO which is almost two-fold 
of the original amount. The history serves as a lesson in comparing it with 
the Connecticut Avenue Bridge. This structure "built in 1907 at a cost of 
§846,331.80, is a concrete arch 'bridgQ 1341 ft, long. The amount spent on it 
for actual maintenance is negligible • The bridge is in as good a condition 
todai' as when it was first constructed* Fig, 3 is a picture of the Connecti- 
cut Avenue Bridge as it appears today; taken from the west side, loolcing south, 

i>:aintenance started on the Calvert Street Bridge in 1696 when 
$289.00 urais spent to repair the wooden floor. Approximately ^60,000, which is 
over one-half of the total maintenaQce costs, were due to the repairing and 
replacing of the lorid^^e floor. In 1922, a new deck was installed vjith steel 
Joists, laminated floor, and asphalt surface, at the cost of ii^ii^OOQ.OQ, 


Prior to this tice approximately ^£9,000. 00 had "been spent in repairing the 

floor; since that time less than 

§2,000.00 has been spent for the 

saine purpose. Pig. 4 is a picture of 

the floor as it appears today, lo Dicing 

west, Jiecords show that from 1698 

until 1922, ^97,339,07 was spent for 

fixing the floor, painting , replacing 

steel, and miscellaneous repairs; an 

average of $3,639.00 a year. It Is 

interesting to note that up until 1533 

approximately ^15,000.00 was spent on 

Pig. 3 

painting; an average of vlt'5'56.00 each 
time the bridge was painted. Of the 
Eiajor itens raaking TXp the total i.iainten- 
ance cost, the replacing was the least, 
'Jhis is estimated to be approxii^ately 
$9,000.00. By an Act of Con^;resa, the 
Capital Traction Company vras compelled 
to pay one -half of all of the ii.aintenance 
costs on the bridge. 

Fig. 4 



At the time the Calvert street Brid^ was constructed, it was 
sufficient for the t^'pe of traffic that went over it, but as time went on 
excessive Xive loads passing over the bridge caused it to vibrate, 'i'hls 
was due to the fact that part of the roadway was built on a cantilever 
beam. Pedestrians wadicing on the bridge at the tioe whan these excessive 
live loads passed over it became so intensely frightened that they refused 
to use the bridge, believing it to be unsafe, in 1312 the width of the 
roadway was reduced to 26 ft,, cutting out all the roadway over the canti- 
lever "beams and eliminating the vibrations. 

Fig, 5 shows a cross section of the roadway before and after 
the reduction* 

it is the opinion of the general public of today that the bridge 
is of inadeq'Jate strength to hold tlie loads passing over it, and that it 
has been condeirjied several ti;.ias, but this, however, is not true. Engineers 
have proved it to be of sufficient strength, 


An accident, fatal to a motorist, v;jiOse auto drove throui^'h the 
handrail of the bridge, was the cause of the installation of traffic guards 
on both sides of the roadway, it was during the winter of 192S when this 
accident occurred; the roadway being covered v.dth snow and ice, caused the 
driver to lose control of the car, and plunge 45 ft., from the bridge floor 




'^"■■mt ijF 


a wty 


C/foss Sscr/or\/ Bero/^e PeoacnoN 



Fis. 5 

Cross Seer ion Afte-/^ ^BDucr/oh/ 
or /PoAoy^AY 


to the ground "below. Although claims were brought agalnat the Ji strict, 
it was proved that the purpose of the hand rail was not to keep trsiffic 
within the roadway of the bridge, and did not have to be of sufficient 
strength to do so. In spite of this, after much > cont9iLpia.ting)| a traffic 
gfuard was installed in 1926. I'hese guard rails may be seen in fig. 4, 


Be cords show that the first mention of a new bridge v/as made in 
October, 1^14, when the Uistrict engineers reconmended appropriations be 
made either for the reconstruction of the old bridge or for the construction 
of a new. It was not imtil January, 1317, that the recominendation was con- 
sidered. At this time an appropriation of $4,000.00 was raade to be expended 
for the design of a new brid^^e, but was termed by the District engineer as an 
insufficient sum, and an appropriation of ;J5,000.00 was reconaiiended; this, 
however, was not given until a later date* This appropriation brought in 
siJggestions from all bources stating the type of bridge that should be built, 
Several reco: -mended it to ba iiirr.ilar to the Connecticut Avenue spari, some, 
liice other bridges of the world, and the rest, ideas of their own. The 
suggestions of the materials of which the bridge was to be construe tod were 
equally divided betv/een steel and concrete. 

By the law it vts.s required that street car traffic go uninterrupted 
during construction of the new bridge. The engineers were faced with tiie 
probleia of abiding by the law and still build the new bridge on the same site 
as the old. The only solution that could be found was to build a railway 


trestle containing a single track alongside of the present britJee. Th6 
street cars were to pass over this during the period of construction of 
the new bridge, v/hich wa^ to be approxijmtely two years, the estimated 
cost of the trestle was $41,500.00. iJue to the lacJt of appropriations, 
the idea of tuildiiig the trestle, and construction of the new bridge was 
teraporarily abandoned. The thought of building the bridge on a site other 
than that of the old bridge was also dropped. 

In September, 1J18, an inspection of the bridge showed it 
to be of a;.iple strength but of insufficient width to aQCO:"jnodE.te the 
railway and vehicular traffic i>assing over it. 

In October, 1313, an estiiiiate of the reconstruction of the old 
bridge was ;iven at vl?3,141.00. At the sa,.je time an estiinate on a new 
bridge was given at yl, 179, ODD. 00, and it w;.-3 recomjiended that ;jp500,000.00 
be appropriated for its construction; however, the funds were never 

Although several recorar.iendations v/ere made, it was not until 
September, 1^32, that these recommendations were given serious consideration, 
The old plans of the new bridge were discarded and funds were appropriated 
to be expended for a new design. The l!odjeski, Liasters and Case, inc., of 
New lork City, Consulting Bngineers, drew up the new plans. 

iVo proposals v/ere set forth to allow the new bridge to be 
built on line of the old, and to allow the continuity of traffic flow. 
These were, the bi^ilding of a railway trestle ss stated before, or the 
moving of the old bridge, ilie latter was accepted. Fig. 6 shows the new 


"bridge being built on line of the old, 
after the latter was moved 80 f t. , to 
be used ac a detour, looking east. 
Appropriations amounting to $575,000. 00 
were made for the year 1^33-1334 and 
the remainder of $1«£50,000.00 for 
the construction of a new bridge. 

The contract for building 
the new bridge was awarded to the 
John W, Cowper Co., of iiuffalo, K, I., 
which submitted a 'bid of ^928,724,00. 
On the following page is a blue print ol 
all the bi-ia submitted by the differ- 
ent contractors* The bid of the 
John v/, Cowper Oo, includes items 
1, 2a, and 3. 

Fig. 6 





To provide a detotii for vehicular and street car traffic during 
construction of a new Calvert street Bridge, the John Sichleay Jr Co., of 
Pittsburgh , subcontractor, rolled the old steel trestle lure ighing 1,226 tons 
and rising 125 ft, above its lowest pier) from this site to new foundations 
80 ft. south with the aid of five capstans, each poTsered by one horse, and 
two one-man winches, iioving the old bridge was determined by the John W« 
Cowper Co., of Buffalo and 'Vashington, general contractor for the entire 
project, as aore economical than the erectian of a tenporary viaduct, liice- 
wise proposed as an alternative method of taicing care of traffic during the 
period of construction by the Board of Commissioners of the district of 
Colujobia, for which the work is being performed. 

ijcrew Jacks started the great steel trestle, 750 ft, long, upon 
its journey. After a number of short moves, to purmit frequent checking of the 
structure by instruments, the rate of progress was increased, and the trans- 
fer to the new position on concrete foundations was completed in 8 hours, 
between 7;30 a.m. and 3;30 p*iin. , on June 7th, 1334, For purposes of moving, 
each tower leg of the tall trestle was picicod up on u r-rid of steel needle 
beams, and the load at each leg was transferred by means of these needle 
beams and longitudinal girders to steel rollers resting upon line;; of rail 
laid parallel with the direction of movement. With steel-cable hauling 
lines leading from the tv/0 forvferd legs of each tower to a set of block and 
tackle connected to a capstan, the torivers of the bridf^e were rolled aimiil- 
taneously toward the new foundations, the drivers of the horse^-oapstan and 


the opsTstoPs Or" the winches exercisinr; aocnrate control of njovement of all 
points, i'iS" 7 shows the capstan being t\irned by the horse. Pig , 8 the 
■bridge fxom the air, after having reached its new location. 

Fig, 8 


In advance of the moving, approach trestles consisting of 
timlaer bents and steel floor "beams were built up st "both ends of the new 
location, .^teel rails for the car trades were set into plank decking on 
the approach trestle reedy for inanediate connection as soon as raoveraent 
of the bridge was complete. The bridge carried a 16 inch water main, 
electric power lines, and a telephone conduit, all of which were provided 
for during the moving, 

i'o support the steel trestle in its new location, the contractor 
constructed concrete piers on solid rock: or sound bearing material, carrying 
piers down as much as 30 ft, where necessary. 'Jwo lines of 70-lb. steel 
rails were l&id parallel with the direction of movi;ment on each sidtj of a 
bent on timber crib-ing built up from the uneven groui.d surface. The 
cribbing rested upon a Bt.t of £xlO-in, planfcs which assured a lo&d distri-i— 
bution not exceeding 1 ton per square foot during the moving operations. 
On top of the steel rails were placed assemblies of £^-in. steel rollers, 
spaced ana held parallel b,/ means of slotted steel siae plates. 


With the exception of bents 3 and 4 , all of the to-A-er legs 
of the bridge rented on stone masonry piers above the ground line. ;t 
bents 3 and 4, the tov/er legs had been incased in concrete after the 
construction of the bridge to prot'..iCt the steel columns against a 
subsequently placed fill. 

-14- . 

At all the expo sod stone piers, the contractor prepared for 
moving the bridge "by installing sets of needle beams directly under the 
cap-stone of the pedistal, removing the next lower course of stone in 
order to place the needles, V/ood wedges tJOk up the bearing between the 
needle beams and the stone courses left in place, as indicated in fig. d, 

These beams io be 
conctvfec/ in place 
when moved iv 
new Foundafions^ 

Hartiwood spreaders 



i! (J /Sione cap 

/HardY/ooel shims 1 xS 


/ \5-l5Pe>42.m. for bents S-6-7-8 
—[SSTF/^USIk forbenfs 1-2-910 

rftardwood shims ?'x8' 

•^i'lO^ cfyc.of columns 

'T» f 

■1- tnr*in(y-t vt-i^ 

12 /, 3f.8lb. spliced if necessary 1 

Coniinuous 701b. rail 

BuJ^ ^ ^^ "^ ^^^ ^^^ ^^^^e^e-cribbingxi^riong^Heiglrf 

IQ'lj roller shoes 4 long 

72 steel rollers S'c.toc. 

of cribhirig go verned "by presen ti ' 


y 9}^VA^ 

Fig. 9 

Under the needle beams, which were installed pr,rallel with the 
center line of the bridge, the movers placed two pairs of l£-in. beams 
12 ft. long, one pair at each end of the needles, directly above the steel 
rails of the tracK prepared for rolling, 'i'hese pairs of 12- in. beams 
rested upon two sets of steel-shod rolling shoes bearing directly upon the 
assemblies of 2ij--in, st.iel rollers. One beam of the pair was spliced by 
meaxis of a connecting member to one member or beam of the other pair 
traveling on the same set of rails, thus framing the temporary supporting 
steel under the two coluons of the bent into a rigid carriage. 


Fig, 11 

I ib-li'iniMiilAt 

1 Ml]ll'ltl,hM>4l I'lu'l 


'■■ ^ roof X?- 41 


Section 8-B 

Columns io b> bu-ned 
off at Tnih point 

Column for bent I 


/g roar 


ilg. 10 is a picture of a typical bent and shows this up very 
clearly. Batteries of screw jacks were eniployed to raise and lov-'er each 
tower leg at the 
■beglmiing and at 
the end of its 
journey. Fig. 11 
shows these screw 
Jacics in actual 

bents 3 and 4, the 
contractor bolted 
steel brackets to 
the colunais, after 
transferring the 
load by means of 
these brackets to 
the temporary 
carriatres and track 

US a? lfe .1 

Continuous \ j 

4-t5'l^m 6a8lb.xl2'—> W- i ■ 


■^j ja Eij ji 

..■2-2^ 8 P 
' m 75.5/b. 

,v>ik l2"l(S)M8lb.continyous 
7^ to ofber column-.. 


3W/d.x/2' '*! 

1^ ^^^!^{J\^M!^ 



Fi m 


\Maximum '■- Conf/nuo us 2x10 planking 

yp'^t " w.u"^A ' ^v.i.^-'.,' .y^ 

Fig. 12 

structure, workmen burned off the columi.s below the brackets. I3xcept for 
using bolted steel brackets instead of capstones, the procedure at these 
bents were similar to that at the other ttowera. Pig. 12 shows a diagram 
of bents 3 and 4, and fig. 13 is a picture of the same bents just prior 
to bein^ burned off belo-v the brackets* 




Fis. 13 


Horse-pov/ered capstans and hand-ptmered. v^inches were selected 
for the moving optiration because the old-fashioned devices provide the most 
depeda"ble and the most easily regulated control of motion at a number of 
scattered points. After study of severi.1 hauling hoolc-ups, the layout 
indicated on fig. 14. The fig. jjives both the vertical load at each bent 
and the horizontal pulling force required to overcome inertia and frictional 
resistance of the steel rollers. 

Srew Jacks of 5-ton capacity operating against the rear ends of 
the carriages started the bridge on its movement from the original position. 


i'he contractor had intended to move the structure only 4 inches hy this 
means, but the jacics shoved the bridge so easily and smoothly that the 
movers decided to extend them to their full length of S-g- inches. 

Beyond this point the moving was ace on^jli shed by the hauling 
tacicle rigged ^xp to the capstans and winches. At each of the five towers, 
an eight-part line of 5-in. steel cable was rigged up to a houae-moving 
capstan operated by a horse. ^■. four-part line reeved to a hand crab sufficed 



.5-ton s<^mif btnfUa I \ 

»i«- J(7 H< 90' ->k JO ->w- 

C.i.-fj YCLIh.2 C.L.No3-'\ V-CINoA 




C.LHo.l'^' ^C.llh.9CL/to3^ y-ci.}h.rP 


C.L. ofbr/alge 

1 1^ befyveen 


C-L at bridge new hctietion' 

H V- Hancf crab i 

Deaef man g_ 



Capsfdrt -■' 

Location of capstans and 5 
d^ei^ men tubs c/eferrrfinect 
by fitild condifions 


Corps fa/7 


Fig. 14 

to supply all the needed pulling force at each abutment. V/lth the siraal- 
taneous application of pulling pov.-er at seven points, the bridge moved 
forward alov/ly ani uniformly on its rollers. 

For the first 7 fe^at after the shove with the screw jaci:s had 
been completed, the bridge was pulled forward at the rate Of 6 inches at 


a time to permit 
tha frequent checklns* 
required of the 
alignment and grade 
bet een pulls, For 
the remainder of the 
distance, the length 
of the IndividTjal 
moves was increased 
to 12 inches. The 
engineers continued 
to maice careful checics 
at several points, 
"both for the ali 71- 

Fig. 15 

ment and the grade. At no point did the brid{;e i^-et more than Igdnches out 
of level, and alignment was maintained within 2 inches throughout. Close 
observation of tlie structure daring jaoveuent revealed no unilue stresses. 

At the end of the move, screw jacks levered the grillages on 
the new concrete piers, as shown in fig. 15, and the grillage beam^j were 
concreted in place with high-early stregth concrete. 

Pig. 16 is a picture taken of the bridge during the process 
of moving, looking east. 



I'he l^ew Calvert litreet Bridge, now more than AO/j finished, will 
be of reinforced concrete having three arches faced with Indiana limestone, 
totaling over 750 feet. The with of the new bridge, including the sidewalfcs, 
will "be 84 feet, its height 125 feet. Fig 17 gives a general viev, of the 

began June 15,1934. Jue to 
conditions at the site it was, 
necessary to excavate about 
3,030 cubic yards of roclc in 
excess of the original 
estimates. The Job is pro- 
ceeding in orderly fashion , 
great care having been 
exercised in the choice of 
p07/er tools comprising the 
contractor's plant and in the 

adoption of novel construction methods. I'he cotirpleteness and hi^jh state of 
the nsachinery items utilize! is striking. Power saws, pneumatit. tools for 
riveting and drilling, portable air coiapreusors, concrete vibrators, and 
compllinentory equipment — either driven by electric motors or gasoline 
engines, no steam being used on the job — are being utilized. 

Pig. 17 

13 '^ 

FoiOT sets of steel arch center a — two pairs of like curvature — 
supplied by the Blaw-Knox Co. ,Pittsburghi Pa., are "beintj used to support 
the span forms. I'he care with which the operations are being carried 
forward is indicated bj? the permanent chsracter of the supports installed 
for the arches, ^ach pair is set up in place on rollers which operate on 

Fig, 18 

Fig. 19 

a steel rail, running the width of the bridge. After erection the centers 
are jaclced uo during building of the forms and pouring of the concrete, 
following which the jacics will be lowered so that the arches may be moved 
along the rail to the position of the other set of reinforced concrete 
arches when the operi-tions will be repeated, pig, iq ehows the erection of 
the steel arch centers for the middle arch, and fig , 13 of those in place 
for the west arch. 

Al though the general design of the bridge calls for four separate 
reinforced CDncrete arches, with 3 outer, £ faced v/ith concrete, viewed 
from "beneath the structure will appear tD "be solidly constructed with 
space "between the arches enclosed "by precast reinforced concrete arch slabs. 
'xhe slabs 8' x ll^'' x 19' — approximately 6 tons, are "beiny cast at a 
special yard set-up "beneath the dredge, v,ith oiX-'burninj heaters. The slabs 

Fig. 20 

Fig. 21 

will meet to form a V-^oint. 

The various coars s of limestone facing v.- ry in thictcness 30 that when the 
concrete "bacJcin^j Is poured the construction becomes virtually monolithic. 
By settin^^ the stones in place through the use of swinging scaffolding and 
building only an interior form, the use of exterior forms are eliminated. 


All concrete for the structure is ready 
mixed — "by 4 of the latest type 1 yard 
capacity Slaw-Knox buckets which are 
swung into position by dorriclcs or cranes 
— in ail, 50,000 cubic yards of concrete 
will "be required. 

Fig. 20 shows the west 
abutment, and fig, £1, one of the middle 
piers; both of these with ;?ig. 18 give 
a good conception what the stone facing 
will look like when the bridge is 

Jar ricks oi" like type have 
been set up at each end of the bridge, equipped with 100 ft. baoms, having a 
capacity of 15 tons. These can be seen in fig. 22, 

Fig. 2£ 

The construction of the new bridge, far ahead of schedule, is 
due to be completed by October 1935. On the following page is an architects 
conception of the brid^^'e as one rai -ht see it from the Connecticut Avenue 


Department of Jirid^^es, Jist . of uol. Comm. ( official files J 

Th6 John ',7. Uowper Co., '.Yashington, D.C, , { official files ) 

Construction L^thods , Aoigust 1934. 

ilsiiufacturers itecord iJaily Construction Bulletin , ITovera'ber 1934. 

The ..ashiuprton limes, TJovember 10» 1934,