Thirty Years of PrestressedConcrete Railroad Bridges

Donald Goldberg, P.E.Vice PresidentGoodkind & O'Dea, Inc.New York, New YorkClifton, New JerseyHamden, Connecticut

Traces the progress in prestressed concrete railroadbridges from simple short span structures built in the950s to the advanced designs and complex

structures of the 1 980s.

Engineers who design structures forrailroads are often considered

more conservative than those who de-sign structures for highways or otherfacilities. Two explanations may be of-fered for this observation. First, railroadstructures must sustain considerablygreater loads than highway bridges orother structures. Also, because there aregenerally fewer opportunities for de-tours, rail traffic is likely to be dis-rupted significantly when a bridge istaken out of service for even a shorttime. Considering these factors, it isunderstandable that railroad bridge en-gineers are cautious about implement-ing untested or unproven structuraltechniques.

As far back as the Civil War, and be-fore, railroad bridge engineers builtbridges that might not be tried today(Fig. 1).' However, experience hasshown that, given sufficient testing of anew concept, it will not be long beforethat concept is adopted by the railroadengineer.

While construction was commencingin 1950 on the Walnut Lane Bridge (thefirst major prestressed concrete bridgeto he built in the United States), thePortland Cement Association in Sep-tember of that year was load testing aprestressed concrete railway trestle slabin their research and developmentlaboratories near Chicago, Illinois.

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Fig. 1. Cedar Creek trestle, Raleigh and Gaston Railroad, North Carolina.

In October 1953, full scale load testswere made by the Association ofAmerican Railroads on a 19 ft (5.8 m)prestressed concrete trestle slab at theU.S. Bureau of Reclamation in Denver,Colorado. A summary of this researchwork is given in Refs, 2 and 3.

By March 1954, trains of theChicago-Burlington & Quincy Railroadbegan operating near Hunnewell, Mis-souri, over the first prestressed concreterailroad bridge in the United States[Figs. 2 and 3(a)]. While only a modest19 ft (5.8 m) long slab was used as partof a multispan structure, this slab re-presented another first for the pre-stressed concrete industry in theUnited States.

Between 1954 and 1957, railroad en-gineers took advantage of continued re-search by the Association of AmericanRailroads and the experience of high-way bridge engineers. 3' 4 They designedand constructed still longer spans,using primarily slabs and boxes. Thestructures had waterproofing, ballast

and track placed directly on the slab orbox. This type of construction was par-ticularly suited for replacement ofexisting timber trestles with minimuminterruption to train operations.

Fig. 2. Bridge No. 38.64 on the CB&QRailroad near Hunnewell, Missouri.

PCI JOURNAL/September-October 1983 79

An excellent description (togetherwith pertinent design details) of someof the prestressed railroad bridges builtin the United States in the fifties isgiven in Ref. 5. Fig. 3 [(a) through (g)]shows typical sections of those earlybridges.

The early prestressed concrete railroadstructures were constructed in spans of20 to 30 ft (6.1 to 9.1 m), matchingexisting timber spans. More often thannot, these superstructures were sup-ported on prestressed concrete pilesdriven through the existing trackstructure, with construction scheduledto minimize interruption of traffic.

The 703 ft (214 in) Salkehatchie Rivertrestle in Yemassee, South Carolina[Fig, 4], was built by the Atlantic CoastLine as one of the first major pre-stressed concrete slab railroad trestlesin the United States, It replaced a shortsteel span and a creosoted timber tres-tle. Further details of this structure ap-pear in Ref, 5.

By 1957, the Santa Fe Railroad hadcompleted two bridges with two 70 ft(21.3 m) spans at the Air ForceAcademy. Designed by Skidmore,Owings & Merrill of Chicago, Illinois,each of the 70 ft (21.3 m) spans con-tained four modified T-shaped girderspost-tensioned with eleven 16 x 0.25 in.(6 mm) cables. Designed for Cooper'sE-72 loading, each girder weighed 60tons (54 t) [Figs. 5 and 3 (b)]. For moredetails see Ref. 5.

In 1959, the Great Southwest Rail-road completed two structures with67-ft (20.4 m) spans over the Dallas-Fort Worth Turnpike and State Ex-pressway 360 in Arlington, Texas. De-signed for Cooper's E-50 loading byPowell and Powell, Consulting En-gineers, Dallas, Texas, each span con-sisted of six modified Type C TexasHighway Department girders. The gir-ders were pretensioned with 44 7h6-in.(11 mm) strands and weighed 19.5 tons

rt1(a) y<:

(b)

d {

(c)

ILTTJ(d) (e)

_(f)

(9)

Fig. 3. Cross sections of various earlyrailroad bridges: (a) Chicago, Burlington &Quincy Railroad; (b) Atchison, Topeka &Santa Fe Railway (Colorado); (c)Galveston Terminal Railroad; (d)Atchison, Topeka & Santa Fe Railway(California); (e) and (f) Chicago & NorthWestern Railway; and (g) GreatSouthwest Railroad.

(18 t) each [Fig. 6 and 3(g)]. Ref. 5 pro-vides more details of this structure.

In 1966, the Frisco Railway openedits third trestle using prestressed con-crete box girders with the ties restingdirectly on the boxes. The first trestle,built near Gattman, Mississippi, in De-cember 1963, was a seven-span struc-ture (Fig. 7) with a total length of 145 ft(44.2 m). It was designed for Cooper'sE-65 loading with AREA diesel impact.The box girders are approximately 20 ft(6.1 m) long, 3 ft (0.9 in) wide, and 2 It 9in. (0.8 m) deep, and are prestressed

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Fig. 4. Atlantic Coast Line's Salkehatchie River trestle in Yemassee, South Carolina.

--. .......Mw.n....._,_-wi...0 i . w -"■.

Fig. 5. Santa Fe grade separation railroad crossing at the Air Force Academy,Colorado Springs, Colorado.

PCI JOURNALSeptember-October 1983 81

with 36 %-in. (10 mm) 270 ksi (1062MPa) strands. The two girders in eachspan are 5 ft (1.5 m) on center and areanchored to the piers at one end andfree to move at the other. Installation ofthe deck required only about one hourper span. Four spans were changed oneafternoon between trains and the re-maining three the next morning (Fig.8)s

The 1966 project, near Potts Camp,Mississippi, comprises 24 spans of tres-tle approaches to the Main TippahRiver crossing. Most of these are 27 ft(8.2 m) spans designed for Cooper'sE-80 loading with impact, and required3 ft (0.9 m) wide by 3 ft 3 in. (1.0 m)deep box girders. The prestressingforce was developed with 31 ½-in. (13mm) diameter, 270 ksi (1062 MPa)strands.'

Each pier is composed of three mod-ified 22-in. (559 mm) PCI-AASHTOhollow-core square piles with cast-in-place reinforced concrete caps. Thebeams rest on neoprene bearing pads

Fig. 6. Lifting into place a precastprestressed girder on the GreatSouthwest Railroad over the Dallas-FortWorth Turnpike, Arlington, Texas.

between precast concrete guide blocksattached to the pier cap by means of anepoxy adhesive.

Fig. 7. Frisco Railroad trestle, Gattman, Mississippi.

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Fig. 8. Girder being placed on the Frisco Railroad trestle, Gattman, Mississippi.

In 1968, the Canadian Province ofSaskatchewan constructed its first pre-stressed box girder railroad bridge forthe Albert Street subway project in Re-gina. A four-span twin railway bridge

Fig. 9. Albert Street subway, Regina,Saskatchewan.

designed by Reid, Crowther andPartners, Ltd., used boxes fabricated byCon Force Products, Ltd. (the forerun-ner of Genstar Structures Limited)which were 45 in. (1.1 m) deep by 48in. (1.2 m) wide with a maximum spanof 53 ft 2 in. (16.2 m). Fig. 9 shows thebridge under construction.

The girders were designed forCooper's E-70 loading plus impact. Therequired prestress force was achievedwith 42 `Is-in. (13 mm) 270 ksi (1062MPa) strands with the bridge being lat-erally post-tensioned with eight r -in.(13 min) strands per span. The finalforce for the post-tensioning was 25kips (111 kN) per strand. Prairie WestConstruction Ltd., the general contrac-tor, erected each bridge, excluding lat-eral post-tensioning, in two days.7

While not a railroad structure in thetrue sense, a precast prestressed tunnelprovided a solution to constructing afour-lane divided highway over acurved railroad track, with a skew ofmore than 74 degrees, and at the same

PCI JOUR NALJSeptember-October 1983 83

F

time provided flexibility for futureexpansion — with no disruption of rail-road traffic (Fig. 10).8

Designed for the Connecticut De-partment of Transportation by Hayden,Harding & Buchanan, of Boston, Mas-sachusetts, the tunnel was completed in1970 by the general contractor, White

Fig. 10. Precast railroad tunnel, Berlin,Connecticut.

Oak Corp., with Blakeslee Prestressproviding the prestressed concrete. Thetotal structure length, includingwingwalls, is 800 ft (244 m). Thecenter-to-center dimension betweenfootings is 42 ft 6 in. (13 m) with a clearvertical height from top of track tounderside of arch of 20 ft 4 in. (6.2 m).

The structure consists of 94 pairs ofarch units, each approximately 6 ft (1.8m) wide, 18 in. (457 mm) thick, andwith a chord length of 35 ft 8 in. (10.9m) along its centerline axis. Units onthe outside of the curve were fabricated%-in. (16 mm) Ionger than the insideunits to compensate for the curvatureeffect.

Each section contains 12.5 cu yds (9.6m') of concrete, 2500 lbs (1134 kg) ofreinforcing bar cages, and three post-tensioning tendons. The sections werecast on their sides using two-part,custom-built forms with one side fixedand the other movable on rails.

The footings are considerably furtherapart than needed for tunnel clear-ances, allowing for installation withoutusing sheeting or delaying train opera-tions. The arch sections were also setwithout interfering with trains. Fig. 11shows the tunnel under construction.

Fig. 11. Precast railroad tunnel, Berlin, Connecticut.

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Fig. 12. 12. Canadian Pacific Railroad, Regina, Saskatchewan, after completion.

Having seen the success of the previ-ously constructed Albert Street subwayprestressed concrete railroad bridge, in1969 the City of Regina, Saskatchewanconstructed a modified standard I-girder bridge', carrying the CanadianPacific Railroad over a limited accessroad in the city with spans of 45, 63, 63,and 45 ft (13.7, 19.2, 19.2, and 13.7 m),Fig. 12 shows the bridge upon comple-tion.

The bridge was designed for the city

by Reid, Cmwther & Partners Limited;Con Force Limited provided the gir-ders to the general contractor, PooleConstruction Limited, all of Regina.

The I-girders are similar to the stan-dard AASHTO-PCI girder, but arereally a Con Force Limited P-40 withthe top and bottom flanges the samewidth (Fig. 13). Design loading onthese bridges is Cooper's E-72 plus im-pact. The 44 ft 2 in. (13.5 m) girdersused 12 '/z-in. (13 mm) 270 ksi (1062

Fig. 13. Canadian Pacific Railroad, Regina, Saskatchewan, under construction.

PCI JOURNAL/September-October 1983 85

Fig. 14. Pretensioned box girder being lifted into place on the Southern PacificRailroad, Kyrene Bridge over New Superstition Freeway, Tempe, Arizona.

MPa) strands and the 63 ft (19.2 m)girders used 22 '12-in. (13 mm) 270 ksi(1062 MPa) strands of which 14 werestraight and 8 draped.

A laminated neoprene and steelbearing, used at both ends of each gir-der, performed exceedingly well. Acomposite cast-in-place, 4000 psi (27.6MPa) 8½-in. (216 mm) thick concretedeck was placed atop these girders, andNo. 5 mild steel reinforcing bars wereplaced in both directions at middepthof the top slab, Diaphragms wereplaced on each girder at the bearingpoint, one-quarter point, and atmidspan.

In 1969, the Arizona Department ofTransportation awarded a contract forwhat was then believed to be theworld's longest pretensioned concretebox girder for railroad bridges.10

The two-span structure, which carriesthe Southern Pacific Railroad's KyreneBridge over New Superstition Freeway

in Tempe, Arizona, is 17 ft (5.2 m) wideand 250 ft (76.2 m) long. It is con-structed of four box girders per span,each measuring 3 ft 5 in. (1.0 m) wide, 6ft 8 in. (2.0 m) deep, and 100 ft 6V in.(30.6 m) long and weighing 89 tons (81t) (Fig. 14). Fifty-six z-in. (13 mm) 270ksi (1062 MPa) strands totaling over onemile (1.6 km) in length were used foreach girder. Fig. 15 shows the pre-stressing steel and mild steel rein-forcement in place prior to concreting.

The structure was designed by theArizona State Highway Department'sStructure Section, under the directionof Martin Toney, and Ronald Brechler.The boxes were fabricated by TPAC, aDivision of the Tanner Companies, forthe general contractor, Tanner Bros.Contracting Company of Phoenix.Awarded in the spring of 1969, thecompleted cost was $50 per sq ft ($538per m 2 ), a modest sum for railroadbridges even at that time (Fig. 16).

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Fig. 15. Prestressing steel and mild steel reinforcement for box girder. Southern PacificRailroad, Kyrene Bridge over New Superstition Freeway, Tempe, Arizona.

Fig. 16. Completed structure. Southern Pacific Railroad, Kyrene Bridge over NewSuperstition Freeway, Tempe, Arizona.

PCI JOURNAL/September-October 1983 87

Fig. 18. L & N Railroad over CharlotteAvenue, Nashville, Tennessee.

At the same time, the L&N Railroadwas renovating a bridge over CharlotteAvenue in Nashville, Tennessee, byusing precast prestressed concrete boxbeams." Since only two of the fourtracks could he taken out of operation atone time, the bridge was built in stages.Each stage required an average of onlytwo weeks to complete, an advantage of

prestressed concrete. Fig. 17 shows thebridge under construction.

Each stage consisted of erecting four3 ft (0.9 m) wide, 54 in. (1.4 m) deep,precast prestressed box beams per spanfor a total of eight per stage. Each stageis separated by a 22 in. (559 mm) wide,4 ft (1.2 m) deep precast filler beam,also prestressed. The recesses formedby the filler beams provided space for acast iron drain trough between thetracks. The walkway is isolated fromthe track superstructure by joint mater-ia,l to prevent transfer of live load stres-ses. Ballast curbs were formed by theinside edge of the walkway slab and apartial curb cast on the outside trackbeams at the precasting plant afterstrand release (Fig. 18).

All the beams were designed tomaximize the use of the standard formsfor AASHTO box sections. However,dimensional requirements made itnecessary to use special void forms.The box beams are about 50 ft (15.2 m)long and weigh approximately 29 tons(26 t) each. The filler beams, althoughsmaller in size, are solid and weighabout the same.

Each group of beams was laterallytensioned before moving to the nextstage. This tensioning was done with apair of 1-in. (25.4 mm) diameter tierods, one at 15 in. (381 mm) and thesecond 30 in. (762 mm) below the top ofthe bean, and about 15 ft (4.6 m) oncenters. By staggering and crossing tworows of tie rods at the filler beams, eachstage was tied to the previous group,resulting in a continuous lateral ten-sioning for the full 54 ft 4 in. (16.6 m)bridge width. The limited room forerection required the use of segmentaltie rods connected by threaded coupl-ings.

The structure was designed by HenryForte, in association with Barge, Wag-goner & Sumner, for Metropolitan Gov-ernment of Nashville, Tennessee; pre-stressed concrete was supplied by DixieConcrete Pipe Co., also of Nashville.

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Fig. 19. Canadian Pacific Railroad Dixie Road grade separation, Mississauga, Ontario.

The Dixie Road grade separation atthe Canadian Pacific Railroad in Mis-sissauga, Ontario, which was opened totraffic in 1969, is composed almost en-tirely of precast prestressed concrete,allowing most of the major work to becompleted in six months despite severeCanadian winter weather (Fig. 19),12

Two spans of precast prestressed boxbeams, 3 ft (0.9 m) wide, 41 in. (1.0 m)deep and 57 ft 4 in. (17.5 m) long, areused to carry the three railway tracksover the four-lane highway. The designloading was Cooper's E-70 with impact.Deflecting 32 of the 46 r/2-in. (13 mm)diameter, 270 ksi (1062 MPa) strands inthe web of the box beams, using 6000psi (41.4 MPa) concrete, and prestress-ing to 30 kips (133 kN) per strand re-sulted in a very shallow bridge. Thisallowed the use of a gravity stormsewer system in the depressed highwayrather than a pumped system and addedto the economy of the project.

The 16 girders per span, weighing 33tons (30 t) each, were connected lat-erally with 1'/4-in. (32 mm) tie rods

torqued to 30 kips (133 kN) tension.These rods are at the diaphragms lo-cated at both ends and at the thirdpoints. Joints between beams are filledwith an epoxy adhesive. A butyl mem-brane was placed over the girders, fol-lowed by 18 in. (457 mm) of granularballast.

The retaining wall consists of 2000lineal ft (610 m) of reinforced precastconcrete panels 10 ft (3.0 m) wide, 8 in.(203 mm) thick and varying in heightfrom 9to26it(2.7to7.9rn). 12 Fig. 20shows the retaining wall in place. Thepanels are supported by 167 precastT-shaped pylons, 3 ft (0.9 m) wide atthe front face, 2 ft (0.6 m) wide at theback, and spaced 12 11 (3.7 m) apart(Fig. 21). A continuous neoprene bear-ing strip separates the panel from thepylon. Small mull panels sit on top ofthe pylons between the large panels tocomplete the wall.

Footings, 6 ft 6 in. (2.0 in) by 6 ft (1.8m) by 3 ft (0.9 m) deep, were cast andducts were provided through the pylonsand footings to line up with holesdrilled into the shale below. Post-

PCI JOURNAL/September- October 1983 89

Fig. 20. Dixie Road grade separation precast retaining wall.

Fig. 21, Dixie Road grade separationprecast retaining wall.

tensioning tendons were then fastenedinto the rock using CCL rock anchors.The Iongest pylons used 18 '/2-in. (13mm) diameter, 270 ksi (1062 MPa) pre-stressing strands running through twoducts in each pylon. As the earth wasbackfilled behind the wall, a pre-stressing force was applied in threestages, thus serving to reinforce the py-lons against bending in addition to pro-viding stability against overturning.

An elevated sidewalk under thebridge consists of vertical precastpanels connected at the top to the py-lons by 1¼-in. (32 mm) diameter steelrods. A horizontal cast-in-place concreteslab forms the walkway.

Designed by McCormick, Rankin &Associates, Ltd., Port Credit, Ontario,the structure is owned by the County ofPeel and the Canadian Pacific Railroad.Precast concrete was manufactured by

90

^m

SECTION- PRESTRESSED CONCRETE GIRDER

LENGTH 0-0 59'-IO°LENGTH c-c BRGS. 58`-6`PRESTRESS STRANDS (/2"(V- 7WIRE-270K1162STRANDSINITIAL PRESTRESS PER STRAND 28,100#fc =5000 PSIAPPROX. WEIGHT 150 TONS

Fig. 22. Cross section of L & N Railroad over St. Louis Bay, Bay St. Louis, Mississippi.

A.B.C. Structural Concrete Ltd.,Brampton, Ontario, with post-tensioning by Canadian Lift Slab, Ltd.,Milton, Ontario, for the general con-tractor, Armstrong Bros. Co., Ltd.,Brampton, Ontario.

In 1967," the L&N Railroad com-pleted construction of its bridge overSt. Louis Bay in Bay Saint Louis, Mis-sissippi, on the Mississippi Gulf Coast.Fig. 22 shows a cross section of the rail-road bridge. The structure was designed by Hazelet & Erdal of Louis-ville, Kentucky (Frank B. Wylie, Jr.,principal-in-charge, and Carol] S.Brown, project engineer). Constructionwas by Brown & Root of Houston,Texas. Fabrication was by PrestressedConcrete Products, Mandeville,Louisiana.

The total length of the bridge is10,170 ft (3100 m), which includes a

289 ft (88.1 m) swing span. The bridgecontains 163 prestressed girder spans(Fig. 23). Each span consists of a 60 ft(18.3 m) long by 5 ft 1 in. (1.6 in) deepby 15 ft 2 in. (4.6 m) wide box girderweighing 149 tons (135 t).

} F ^-0^^^1^1I

Fig. 23. L & N Railroad over St. LouisBay, Mississippi.

PCI JOURNALISeptember-October 1983 91

Fig. 24. L & N Railroad over St. Louis Bay. Precast cap on prestressed piles.

Receiving the girders are 78 precastthree-pile caps, 5 ft (1.5 m) wide, 5 ft 6in. (1.7 rn) high, and 16 ft 6 in. (5.0 m)long, which contained shear lugs topermit adjacent girder expansion.Eighty-five four-pile caps, 5 ft (1.5 m)wide, 5 ft 6 in. (1.7 m) high, and 12 ft(3.7 m) long, utilized shear lugs to

Fig. 25. L & N Railroad over St. LouisBay.

maintain lateral and longitudinal fixity.A closeup of this connection is shownin Fig. 24.

Alternating three- and four-pile bentclusters were designed to resist lateraland longitudinal forces, respectively.Each precast, post-tensioned cylinderpile has a 4 ft 8 in. (1.4 m) outside di-ameter with a 5 in. (127 mm) wall andvaries in length from 70 to 120 ft (21.3to 36.6 m) for a total lineal footage of54,915 ft (16738 m). The depth of piletips to good foundation varied from 60to 110 ft (18.3 to 33.5 m) with an aver-age of 80 ft (24.4 in) below mean sealevel.

A total of 2720 curb sections for bal-last retention and pretensioned precastconcrete railroad ties were also used.Every precast component of the struc-ture was prefabricated at the plant; onlythe pile-filling concrete and cap-to-pileconnecting concrete were site-cast (Fig.25).

The same team was selected to de-sign a new bridge over Biloxi Bay inBiloxi Mississippi. The bridge wascompleted in 1979. This 6062 ft (1848m) long bridge includes a 382 ft (116 m)

92

Fig. 26. L & N Railroad over Biloxi Bay, Biloxi, Mississippi. Substructure elements.

Fig. 27. L & N Railroad over Biloxi Say, Biloxi, Mississippi. Overview of construction.

PCI JOURNAUSeptember-October 1983 93

Fig. 28. Long Island Railroad grade crossing elimination, Hicksville, New York.

swing span with 93 prestressed I-beamspans consisting of 372 60-ft (18.3 m)long beams and 675 80- to 110-ft (24.4to 33.5 in) long, 2 ft (0.6 in) square pre-stressed piles supporting precast piercaps (Fig. 26). Prestressed concrete fab-rication was by Biloxi Prestressed Con-

Fig. 29. Long Island Railroad gradecrossing elimination, Wantagh-Seaforddetour tracks.

crete, Inc., Biloxi, Mississippi, for thegeneral contractor, Scott Bridge Com-pany, Opelika, AIabama. Fig. 27 showsthe bridge during construction.

Meanwhile, back east, the Long Is-land Railroad was one of the few north-eastern railroads to use prestressedconcrete extensively. The Hicksvillegrade crossing elimination project (Fig.28), designed in 1959, was the last ofthe Long Island Railroad's projectsutilizing all cast-in-place concrete,which was typical of railroad viaductsin the area. The spans were 25 ft (7.6m).

All the Long Island grade crossingeliminations are constructed in stageswith two tracks of railroad relocated bya detour (Fig. 29) parallel to the exist-ing alignment. With the right of waythus vacated, construction proceeds inthe line of the original railroad bed.

Long Island's first rail project usingprestressed concrete, completed in1970, was a project to eliminate cross-ings at grade in the communities ofWantagh and Seaford in Nassau County(Fig. 30). The tracks are supported onprestressed box beams, 3 ft (0.9 in) wideby 2 ft 9 in. (0.8 m) deep on a span of 29ft (8.8 m) (Fig. 31). The boxes are co y-

94

Fig. 30. Long Island Railroad Seaford Station.

Fig. 31. Long Island Railroad grade crossing elimination, Wantagh-Seaford.

ered with butyl rubber waterproofingwith asphalt plank protection, thenballast and track. Fig. 32 shows acloseup of the platform tee beams.

A total of 67,000 sq ft (6224 m 2) of boxbeams were used for the viaducts; the

station platforms used 33,000 sq ft (3066m2) of prestressed double tees.

The structure was designed by theNew York State Department of Trans-portation, and turned over to the LongIsland Railroad. The fabricator was

PCI JOUR NALSeptember-October 1983 96

Fig. 32. Long Island Railroad grade crossing elimination,Wantagh-Seaford platform tee beams.

Fig, 33. Long Island Railroad gradecrossing elimination, Amityville-Lyndhursttypical girder.

Grand Prestressed, for Del Balso Con-struction Corp.

The Wantagh-Seaford project wasfollowed by Amityville-Lyndhurstgrade crossing elimination project. Thisproject was the first use of prestressedconcrete I-beams (Fig. 33) with cast-in-place concrete slabs for the Long Is-land Railroad. The I-beam depth is 5 ft10 in. (1.8 m) with two girders for theaverage span length of 70 ft (21.3 m)(Fig. 34). There are several spans overroads where the span is 102 ft (31 m)and four beams were used to supportthe track slab. The rails are attached di-rectly to the slab by Landis fasteners(Fig. 35), eliminating maintenanceproblems of ties and ballast and drain-age. The total Iength of the viaduct is17,535 ft (5345 m).

The station platforms are supportedon prestressed I-beams having depthsof4 ft 6 in. (1.4 m) and 5 ft 10 in. (1.8 in)

96

Fig. 34. Long Island Railroad grade crossing elimination,Amityville-Lyndhurst viaduct.

Ill,l11111l I, II fl

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Fig. 35. Long Island Railroad grade crossing elimination,Amityville-Lyndhurst track structure.

PCI JOUR NALJSeptember-October 1983 97

Fig. 36. Long Island Railroad grade crossing elimination,Amityville-Lyndhurst station.

with the canopy over the platform con-sisting of four precast prestressed teebeams with flange widths of 6 ft (1.8 m)and web depths of 2 ft 8 in. (0.8 m)supported on structural steel girdersand columns.

Completed in 1975 (see Fig. 36),Amityville-Lyndhurst was designed byCharles Sells of Pleasantville, NewYork, for the New York State Depart-ment of Transportation and the LongIsland Railroad, with Grand Prestressproviding the prestressed members forHendrickson Brothers, Inc. and HornConstruction Co. Inc., ajoint venture.

Following the Amityville-Lyndhurstgrade crossing elimination was theMerrick-Bellmore grade crossing elimi-nation project designed by McFarIand-Johnson Engineers, Inc., of Bingham-ton, New York, for the New York StateDOT and the Long Island Railroad. Itsconstruction is similar to AmityviIle-Lyndhurst, using I-beams 5 ft 10 in. (1.8

m) deep with spans varying from 61 to75 ft (18.6 to 23 m). Over the streets, 86ft (26.2 m) spans were used with threebeams supporting the track slab (Fig.37).

The total length of this viaduct is4850 ft (1478 m). The canopy construc-tion was modified for this viaduct withcast-in-place concrete piers used tosupport precast prestressed concreteplanks with a width of 4 ft (1.2 m) and adepth of 12 in. (305 mm) (Fig. 38).Platform spans varied from 30 to 43 ft(9.1 to 13.1 m). Construction was com-pleted in 1977 by Horn ConstructionCo., Inc., with prestress fabrication byGrand Prestress.

Because of problems with pigeonsroosting on the sloped bottom flanges ofthe I-beams utilized in Amityville-Lyndhurst, the railroad requested aprecast shape with vertical sides for the

98

_sir......

-

Fig. 37. Long Island Railroad grade crossing elimination,Merrick-Bellmore station.

Fig. 38, Long Island Railroad grade crossing elimination,Merrick-Bellmore station.

PCI JOURNAL/September-October 1983 99

Fig. 39, Long Island Railroad grade crossing elimination in operation, MassapequaPark Station, New York.

Massapequa Park grade crossing elimi-nation project (Fig. 39). Two 5 x 5 ft (1.5x 1.5 m) prestressed box beams werechosen to support the track slab (Fig.39). Spans vary from 63 to 75 ft (19.2 to23 m) for a total viaduct length of 1425ft (434 m). The station platform is sup-ported by two 3x5f1(0.9x1.5m)pro-stressed box beams with spans varyingfrom 67 ft 6 in. to 89 ft 10 in. (20.6 to27.4 m) (Fig. 40). The canopy was con-structed in essentially the same manneras the Amityville-Lyndhurst stations,with precast prestressed tee beamssupported on concrete piers. Figs. 40and 41 show underside views of thestructure.

Massapequa Park was designed byCharles H. Sells of Pleasantville, NewYork, for the New York State DOT andthe Long Island Railroad. Kenville Pre-stress fabricated the prestressed mem-bers for the general contractor, Hen-drickson Brothers, Inc., and Horn Con-

struction Co., Inc., ajoint venture. Con-struction was completed in late 1980-

Another project, suspended duringthe design phase in order to allow con-sideration of depressing the entire rail-road through the city of Mineola, con-sists of a mainline viaduct 7350 ft (2240m) long, and a branch line viaduct 4000ft (1219 m) long, both utilizing threecustom-designed girders per track 4 ft 5in. (1.3 m) deep on cast-in-place piers.The track slab would he the same as theprevious projects without ballast. Sta-tion platforms would also be pre-stressed tees. The design was by Good-kind & O'Dea for the New York StateDOT and the Long Island Railroad.Fig. 42 shows an artist's model of theproject.

in addition to the piles, pier caps, I's,tees and boxes that have been pre-sented here, some railroads are upgrad-

100

Fig. 40. Underside view of Long Island Railroad grade crossing elimination,Massapequa Park Station, New York.

Fig. 41. Long Island Railroad grade crossing elimination, Massapequa Park Station,New York. Note canopy construction of precast prestressed tee beams supported onconcrete piers. The project was completed in late 1980.

PCI JOURNALISeptember-October 1983 101

Fig. 42. Long Island Railroad proposed Mineola grade crossing elimination project.

ing some of their old steel bridges byreplacing timber decks which haveoutlived their purpose with precastslabs. The Santa Fe and Mopac rail-roads have utilized these extensivelyand a number of railroads have adoptedthis as a method of upgrading miles oftrestle, with many miles to go.

J ust as bridge engineers in the UnitedStates have adopted segmental con-struction for highway bridges, the fu-ture looks bright for railroad bridge de-signers to design longer spans by usingsegmental construction, as has beendone in Australia and elsewhere.

Exemplifying the versatility of pre-cast prestressed segmental construc-tion, a dual track railway bridge wascompleted near Sydney, Australia, inearly 1972 (Fig. 43). 9 The Como Rail-way Bridge spans the Georges River 13miles (21 km) south of Sydney andabout 75 ft (23 m) upstream from thebridge which it replaces, owned by the

Department of Railways, New SouthWales. It was designed by Donovan H.Lee & Partners, London, and con-structed by John Holland, Construc-tions, Ltd., Sydney.

The bridge consists of seven simplysupported 159-ft (48.5 m) spans givingan overall span length of 1113 ft 2 in.(339 m). The dimensions approachworld records for concrete railwaybridges both in overall length and sizeof span. [Bridges with longer spans arethe 160-ft (48.8 m) single span skewedbridge at Rotherham, England, by thesame designer, and the five-spanLaVoulte Bridge over the Rhone Riverin France. The French bridge has piersat 194 ft (59.1 m) centers supportingrigid frames with inclined legs at 184 ft(56.1 m) centers.]

Because of the poor soil conditions,92 inclined composite piles up to 166 ft(50.6 m) long were used to support thesouth abutment and piers (Fig. 44).Each pile consists of 12 by 12 in. (305 x305 mm) steel H-sections connecting to

102

^f.

Fig. 43. Overview of Como Railway Bridge near Sydney, Australia.

21-in. (533 mm) square prestressedconcrete piles. .

Each span consists of twin precastt•post-tensioned box girders made from

six segments about 7 ft (2.1 m) wide by12 ft 6 in. (3.8 m) deep. The deck isformed by cast-in-place post-tensioned cantilever slabs.

Segments were railed to the bridge :. a^ T t '(Fig. 45) from an on site casting yard (Fig. 46).

Six segments for each span were ,

placed on a 13-ft (4 in) deep steel ..falsework truss supported on two piersand temporary steel bent between the

two piers with 18 in. (457 mm) spaces '.

between segments (Fig. 47). Tendons }were then pulled through the floor ducts prior to stressing (Fig. 48).

The 18 in. (457 mm) concrete joint __ --__was completed and upon reaching 5000

psi (34.5 MPa), 37 of the 55 tendonswere stressed and then restressed after10 days to recover losses. The remain-ing 18 tendons were stressed after the Fig. 44. Driving prestressed concrete pilesdeck was cast. (Como Railway Bridge).

PCI JOURNAL/September-October 1983 103

Fig. 45. Precast segments being movedinto place (Como Railway Bridge nearSydney, Australia).

Fig. 46. An on site casting yard was setup to manufacture box segments forComo Railway Bridge.

Fig. 47. Falsework truss and temporary steel bent (Como Railway Bridge).

MI

Fig. 48. Pulling tendons prior to stressing(Como Railway Bridge).

The old single track wrought ironbridge replaced by the Como RailroadBridge can be seen in the backgroundof Figs. 45 and 49.

During the same period, the EasternSuburbs Railway in Sydney, Australia,completed two viaducts at RushcuttersBay (Fig. 50) and Woolloomooloo (Fig.51).'5 These segmentally constructedviaducts (Fig. 52) carry two tracks ofheavy rail transit as shown on the typi-cal section (Fig. 53). They were de-signed for the Department of Railways,New South Wales, by Snowy Moun-tains Engineering Corporation, withFowell, Mansfield, Jarvis and Maclur-can as architectural consultants.

Loading was to a standardN.S.W.G.R. electric train loading re-duced to a uniform distributed load of2.15 kips per ft (0.003 kg/m).

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Fig. 49. Completed Como Railway Bridge with old wrought iron bridge in background.

PCI JOURNAL September-October 1983 105

Fig. 50. Eastern Suburbs Railway at Rushcutters Bay, Sydney, Australia.

Fig. 51. Eastern Suburbs Railway at Woolloomooloo, Sydney, Australia.

106

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.. ` .,....

Fig. 52. Segmental units being placed atWoolloomooloo viaduct.

As part of a flood control project inArlington, Virginia, four new railroadbridges (Fig. 54) for the Richmond,Fredericksburg & Potomac Railroadwere constructed from 1976 to 1980utilizing 172 precast prestressed con-crete box girders, all 6 ft (1.8 m) high by4 ft (1.2 m) wide, with approximately a68 ft (20.7 m) span. The design loadingwas Cooper's E80 plus impact. The totalbridge area is approximately 146,000 sqft (13563 m 2). The design was by Dc-Leuw Cather & Company, with fabri-cation by Shockey Bros., Inc. of Win-chester, Virginia.

700

Fig. 53. Typical section of Woolloomooloo viaduct (Eastern Suburbs Railway).

~ r -^

s

: :_ ''^^ r am,

PC h.5

I

Fig. 55. Prestressed concrete railway truss in Japan.

As reported by Ben C. Lerwick, Jr.,Y6

the Japanese have constructed theirfirst prestressed concrete truss bridgefor a railway line (Fig. 55). Segmentsare match-cast in the plant using a newadmixture (Sigma 1000) and low pres-sure steam curing. They are joined bypast-tensioning,

Several prestressed concrete bridgesfor mass transit structures have beenbuilt with fairly long spans. While theloads do not approach normal railroad

"J '" ` loads, they are greater than typicalhighway loadings.

Typical of these, in addition to thepreviously described Rushcutters Bayand Woolloomooloo viaducts in Sydney,is the Byker Viaduct in northeast Eng-land, which is an epoxy glued segmen-ta] railway bridge on a highly curvedalignment (Fig. 56). Constructed partly

. as balance-free cantilevers and partlyFig. 56. Byker Viaduct, England. by continuous cantilevering, the

d

108

Fig. 57. Clichy Railroad Bridge, France.

longest span is 226 ft (69 m). A detaileddescription of the project appeared inthe March-April 1981 PCI JOURNAL."

The Clichy Railroad Bridge (Fig. 57),completed in 1979, has seven spans fora total bridge length of 2000 ft (619 m),with a center span of 280 ft (86.6 m).The Marne LaVallee Viaduct (Fig. 58)includes a bridge over the River Marneand a long trestle with a sharp horizon-tal curvature. The bridge has spans of157 ft 6 in. (48 m), 246 ft (75 m) and 124ft 8 in. (38 m) for a total length of 528 ft(161 m). The trestle is 4490 ft (1367 m)long with an average span of 105 ft (32m). Both projects were designed byJean Muller of Figg & Muller En-gineers, Inc., Tallahassee, Florida.

One of the world's first all concretecable stayed railway bridges was re-cently opened in England by BritishRail. 1R It was designed by the SouthernRegion of British Rail in conjunction

fg

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Fig. 58. The Marne LaVallee Viaduct,Paris, France, was built with precast boxgirders assembled in balanced cantileversusing a launching gantry.

PCI JOURNAL`September-October 1983 109

GA;.

Fig, 59. British Rail over M25 Motorway, Lyne, England.

with Stressed Concrete Design Ltd., forthe Department of Transportation, andcontains two continuous skewed spansof 180 ft (54.9 m) with an overall widthof 38 ft (11.6 m) (Fig. 59). The structurehas solid post-tensioned edge beamsand reinforced concrete deck with twoconcrete towers rising 72 ft (22 m)above the edge beams to support thebridge. Construction started in June1976 and was completed in two yearswith only minimum interruption to railtraffic.

Readers interested in obtaining morerecent information on railroad struc-tures may consult Refs. 19 and 20.

And so, after 30 years, railway bridgeengineers have advanced from a 19 ft(5.8 m) prestressed slab to a two-span180 ft (54.9 m) cable stayed bridge.How far can the spans of railwaybridges reach with prestressed con-

crete? This question is left to be an-swered to the courage of the bridgerailway engineers and those contractorswho can adapt the state-of-the-art ofbridge construction practice to the con-struction of railway bridges. It is un-doubtedly clear that we have onlyscratched the surface in this area andthat many opportunities lie ahead to betapped,

ACKNOWLEDGMENT

The author wishes to thank Messrs. DanielP. Jenny and George D. Nasser, PCI, JackKelly, Biloxi Prestress Inc.; Ronald C.Brechler, Arizona D.U.T.; Caroll S. Brown,Hazelet & Erdal; Michael J. Sheehan, Jr.,New York State D.O.T.; George Pappas,Charles Sells; W. T. Shearman and AI Os-terling, McFarland-Johnson Engineers; andCharles Slavis, Portland Cement Associa-tion, for their assistance in obtaining the in-formation and photographs of the structuresdiscussed herein.

ME

REFERENCES

1. Abdill, George B., Civil War Railroads,Bonanza Books, New York, New York,1961, p. 121.

2. Woolford, F. R., "Prestressed Concretefor Railroads," PC[ JOURNAL, V. 6, No.2, July 1961, pp. 82-96.

3. Ruble, E. J., and Drew F. P., "RailroadResearch on Prestressed Concrete," PCIJOURNAL, V. 7, No. 6, December 1962,pp. 46-59.

4. Drew, F. P., "Studies of Box Beams forRailway Bridges," PCI JOURNAL, V.10, No, 3, June 1965, pp. 46-51.

5. Concrete for Railways No. 58 –Pre-stressed Railway Bridges Come of Age,Portland Cement Association, Chicago,Illinois, 1960, 24 pp.

6. Prestressed Bridge Bulletin, PrestressedConcrete Institute, October-November1966.

7. PCI Bridge Bulletin, Prestressed Con-crete Institute, May-June 1968.

8. PCI Bridge Bulletin, Prestressed Con-crete Institute, May June 1969.

9. PCI Bridge Bulletin, Prestressed Con-crete Institute, November-December1969.

10. PCI Bridge Bulletin, Prestressed Con-crete Institute, January-February 1970.

11. PCI Bridge Bulletin, Prestressed Con-crete Institute, March-April 1970.

12. PCI Bridge Bulletin, Prestressed Con-crete Institute, September-October1970.

13. PCI Bridge Bulletin, Prestressed Con-crete Institute, November-December1971.

14. "Precast Prestressed Segmental RailwayBridge in Australia," PC[ JOURNAL, V.18, No. 5, September-October 1973, pp.105-114.

15. "Woolloomoolo Viaduct," Construc-tional Review, February 1972, pp. 5-12.

16. Ccrwick, Ben C., Jr., "Prestressed Con-crete Developments in Japan," PCIJOURNAL, V. 23, No, 6, November-December 1978, pp. 66-76.

17. Smyth, W. J. R., "Byker Viaduct—Britain's First Prestressed SegmentalRailway Bridge," PCI JOURNAL, V. 26,No. 2, March-April 1981, pp. 92-109.

18. "All Concrete Cable-Stayed RailwayBridge," Concrete International, V. 1,No. 12, December 1979, pp. 12-13.

19. Maughan, R. G., "Precast PrestressedConcrete for RailwaylHighway GradeSeparation Structures," TransportationDevelopment Centre, Montreal,Quebec, March 1982, 85 pp.

20. Railroad Bridges, PCI Bridge Bulletin,Prestressed Concrete Institute, No. 1,1983, 4 pp.

NOTE: Discussion of this paper is invited. Please submityour comments to PCI Headquarters by May 1, 1984.

PCI JOURNAL/September-October 1983 111