HISTORICAL-TECHNICAL SERIES

Precast Concrete SegmentalBridges America’s Beautifuland Affordable Icons

Fora bridge type that would be

come an increasingly popularand successful competitor over

alternative building systems, precastconcrete made a rather unpretentiousdebut in the United States. Indeed, onewonders if the engineers who designed and built America’s first precast concrete segmental box girderbridge in 1973 — the John F. KennedyMemorial Causeway Bridge connecting Corpus Christi and Padre Island,Texas — could have imagined that thissimple, unadomed structure would bethe harbinger of some of the nation’smost beautiful and affordable bridges.

Indeed, thirty years later, precastconcrete segmental construction hasproduced some of the most technologically advanced, visually dramatic,and environmentally sensitive structures in North America as well as in

many other countries throughout theworld. Typically, the precast, prestressed concrete bridge also proves tobe the most cost-effective alternativefor owners, particularly when life-cycle costs such as maintenance andrepair are taken into account.

EVOLUTION OFPRECAST CONCRETE

SEGMENTAL BRIDGES

The European Experience

Originating in Europe, this versatileand economical bridge type emergedshortly after World War II. With theurgent need to reconstruct bombed-outbridges quickly and efficiently, andwith steel production capacity debilitated by war efforts, European designers and builders turned to prestressedconcrete.

How did precast concrete segmental construction become a majorplayer in the modern American bridge industry? While the continuinggrowth in market share for precast, prestressed concrete systems canbe attributed to numerous competitive advantages, this articlepresents an overview of the proliferation of segmental bridges in theUnited States based primarily on five advantages — economy,construction efficiency, durability, design innovation and aesthetics.

Linda FiggPresident andDirector of Bridge ArtFIGG Engineering GroupTallahassee, Florida

W. Denney Pate, RE.Senior Vice President andPrincipal Bridge EngineerFIGG Engineering GroupTallahassee, Florida

26 PCI JOURNAL

The first precast concrete segmentalbridge, the Luzancy Bridge across theMarne River in France, was erected in1946. It was designed and built by Eugene Freyssinet, the French engineerand pioneer whose technical investigations and ingenious advances duringthe first half of the 20th Century madeprestressed concrete a viable construction material.

While numerous precast, prestressedconcrete bridges were built throughoutEurope between 1946 and 1973,American bridge designers did not immediately embrace this new technology, in part because many conventional bridge engineers of the timequestioned the suitability of using precast concrete segments for major orlong-span structures. However, withfurther advancements in technology,precast, prestressed concrete emergedas a strong competitor to conventionalconstruction.

Lee Roy Selmon Expressway

A compelling example of the phenomenal evolution of precast concretesegmental bridges since 1973 ispresently under construction inTampa, Florida — where the Prestressed Concrete Institute (PCI) wasfounded in 1954. The three-lane reversible structure erected span-by-span within the median of the Lee RoySelmon Expressway, on single piersonly 6 ft (1.8 m) wide at the base, willmore than double the toll highway’scapacity within the existing right-of-way while maintaining essential trafficflow during construction (see Fig. 1).Operating in the direction of peak demand (westbound from the suburbs todowntown Tampa in the morning andeastbound in the evening), the 5-mile(8 km) long structure will provide “sixlanes in 6 feet,” preserving most of themedian for future use.

The 3032 prestressed segments [59ft (18 m) wide, about 70 tons (64tonnes)] are precisely cast at a nearbyfactory and delivered by truck duringoff-peak hours. In the immediate areaof the worksite, the inside lanes of thefour-lane roadway are temporarilyclosed while the segments are liftedonto the self-launching, underslungerection girder. During peak commut

segmental bridges in the last thirty years.

ing hours, all lanes are open whileworkers apply epoxy between the segments and post-tension the tendons,without impeding traffic below. Atypical 140 ft (42.7 m) span requiresabout three days to complete.

Designed by Figg Bridge Engineersand built by PCL Civil Constructors,the sculpted curved forms of the superstructure and piers embody the visionof the Tampa-Hillsborough Expressway Authority for an aestheticallyunique bridge — truly, a landmarkstructure. The precast concrete boxgirder has curved geometry in thewebs, corners, and the underside of thebarrier.

The bridge piers also presentsculpted shaping, with curved flares atthe top and a 3 in. (76 mm) recessalong the vertical faces. With a softcolor finish and accent lighting frombelow, the bridge will be a strikingfeature of the Tampa landscape whencompleted in 2006.

Part of a $350 million expansionprogram that includes several miles ofpark-like boulevards providing localaccess to and from the reversible express lanes at each end, the segmentalbridge contains approximately 1.6million sq ft (148,640 m2) of deck.According to the Expressway Authority, the Lee Roy Selmon Expressway

—

____________

Fig. 1. Presently under construction over moving traffic, the Lee Roy SelmonExpressway in Tampa, Florida, supports six lanes of traffic on single piers only 6 ft(1 .8 m) wide, and demonstrates the extraordinary evolution of precast concrete

September-October 2004 27

bridge is being constructed for $65 persq ft ($700/rn2), or currently about 30percent less than other major bridgesin Florida.

This rapid transit bridge is only oneexample of several other significantsegmental bridge projects currentlyunder construction.

COASTAL ENVIRONMENTSAmong the advantages touted by its

champions was the ease and economyof maintenance for precast concretebridges, particularly in coastal environments. Bridge maintenance wasone of the concerns of the Florida Departinent of Transportation (FDOT)engineers in the mid-1970s as theyconsidered replacement options for thedecaying bridges of the OverseasHighway, the transportation lifeline ofthe Florida Keys.

Fig. 2. With the first“as cast” riding

surface in theUnited States, the2.3 mile (3.7 krn)

Long Key Bridge inthe Florida Keys

was completed at acost of $32.66 persq ft ($352/rn2)in1980, confirming

the economicfeasibility of precastconcrete segmental

technology.

Long Key Bridge

A Tallahassee, Florida-based civilengineer with a penchant for innovation, Eugene Figg, proposed precastconcrete segmental bridges as the solution. And further, he suggested thatFDOT request federal funds to financea demonstration project of precastconcrete technology for bridges incoastal environments. When the Federal Highway Administration agreedto his proposal, Figg designed and inspected the construction of the LongKey Bridge. Michael Construction Co.completed the 12,040 ft (3670 m)structure in 1980 — five months aheadof schedule — at a cost of $15.3 million, at a remarkable cost of $32.66per sq ft ($352/m2).

Erected using the span-by-spanmethod, the 103 spans, with typicallengths of 118 ft (36 m), were delivered by barge, installed as a unit,aligned, and then post-tensioned. The

Fig. 3. The longestcontinuous precast

segmental bridge inthe world in 1982,

the Seven MileBridge in the

Florida Keys wasthe first use in

North America ofprecast, match-cast

box piers,assembled with

vertical post-tensioning.

28 PCI JOURNAL

post-tensioning tendons were externalto the box girder web, which reducedmaterial costs and construction time.The Long Key Bridge was the first “ascast” riding surface in the UnitedStates (see Fig. 2).

Seven Mile Bridge

Soon thereafter, Misener MarineConstruction started the nearby SevenMile Bridge. Spanning 35,867 ft(10,932 rn), it was the longest continuous precast segmental bridge in theworld in 1982. The precast segmentsfor the piers and superstructure weremanufactured in Tampa and barged450 miles (724 km) to the erection sitesouth of Marathon Key.

An overhead gantry lifted each ofthe 268 spans [135 ft (41.2 m) typicallength] into position as a unit. The superstructure was erected on precast,match-cast box piers that were assembled with vertical post-tensioning (seeFig. 3). These design innovations allowed a 60 ft (18.3) tall pier to be constructed in one day and three 405 ft(123 m) spans to be erected per week.The $45 million Seven Mile Bridgewas $7 million less than the alternative solution, and was completed sixmonths ahead of schedule. The projectwon a PCI Design Award in 1982.

ENGINEERING ANDAESTHETICS

Eugene Figg’s designs were a decisive demonstration of the constructability, efficiency and economyof precast concrete segmental construction. Founded in 1978, the firm,now known as the Figg EngineeringGroup (FIGG), has continued to pioneer segmental bridge technologythrough advancements in design, construction techniques, and materials.

With numerous “signature structures” built in 34 states, and with construction values exceeding $7 billion,FIGG’s forward-thinking design andconstruction engineers are as focusedon aesthetic achievement as they areon cost and time-saving innovations.The firm’s vision is to create bridgesas timeless works of art that reflect thenatural environment and the spirit ofthe communities they serve.

As a consequence of the firm’s vision, its clients’ projects have earnedmore than 200 awards, including threeof the five bridges ever honored withthe Presidential Award for Design Excellence by the National Endowmentfor the Arts (Linn Cove Viaduct, theSunshine Skyway and the NatchezTrace Parkway Arches discussedbelow).

Linn Cove Viaduct

The 1248 ft (380.4 m) S-shapedLinn Cove Viaduct in North Carolinawas an extraordinary engineering feat.At 4400 ft (1341 m) above sea level,the challenges of the rugged terrainand sensitive ecology of the BlueRidge Parkway’s Grandfather Mountain had perplexed highway engineers

for years, resulting in a “missing link”in this scenic region (see Fig. 4).

The first in America, a precast concrete segmental bridge proved to bethe solution, constructed from the topdown in unidirectional progressivecantilever. The segments were delivered by truck onto the completedstructure as it advanced. This picturesque, $7.9 million viaduct, builtby Jasper Construction, contains everytype of alignment geometry used inhighway construction. This projectwon a PCI Design Award in 1983.

The Linn Cove Viaduct includes reverse curvature, with radii as short as250 ft (76.2 m) and super-elevationsranging from a 10 percent slope in onedirection to a 10 percent slope in theother direction — in less than 200 ft (61m). The concave, octagonal-shaped

Fig. 4. Completed in 1982, the Linn Cove Viaduct, part of North Carolina’s Blue RidgeParkway, was the first concrete segmental bridge in America to be built in onedirectional cantilever from the top down to protect the fragile environment. Black ironoxide in the concrete mix allows the bridge to blend into the natural mountain hues.

September-October 2004 29

precast piers — some as tall as 65 ft(19.8 m) — were vertically assembled.Black iron oxide was added to the concrete so that the viaduct and piers blendwith the rock outcrops. The last segment was placed in 1982 and the bridgewas in operation soon thereafter.

Fig. 5. At a lengthof 1200 ft(366 m),

the SunshineSkyway Bridge

over Tampa Bay,Florida, features

the longest precastconcrete

segmental cable-stayed main span

in the UnitedStates. Able to

withstand windsof up to 240 miles

per hour (386km/hr), the

elliptically-shapedpiers are a critical

design towithstand

Florida’s notorioushurricanes.

In the presentation of the first Presidential Award for a bridge, PresidentRonald Reagan said, “Linn CoveViaduct is not just a roadway on NorthCarolina’s Grandfather Mountain; theviaduct has been designed so that it belongs to, and is a part of, the mountain.”

DESIGN INNOVATIONS

Sunshine Skyway Bridge

Carrying Interstate 275 traffic 175 ft(53.3 m) above the mouth of TampaBay, Florida, the Sunshine SkywayBridge was the first U.S. precast concrete cable-stayed bridge with a singleplane of stays attached to single pyIons, towering 431 ft (131 m) abovethe water (see Fig. 5).

Its 1200 ft (365.8 m) main span isthe nation’s longest precast concretecable-stayed span, and the superstructure’s mammoth trapezoidal box sections, each weighing about 220 tons(200 tonnes), were, at the time, thelargest ever erected for a precast segmental bridge. The precast concretebox sections were manufactured byPOMCO at nearby Port Manatee,barged 4 miles (6.4 kilometers) to thebridge, lifted by an overhead gantry,and assembled using the balanced cantilever method.

Constructed by Paschen Contractorsand completed in 1987, this Floridianicon is famous for its sleek, gracefullines and golden cable stays, thatshimmer in the bright Florida sun andradiate with accent lighting at night.While the elliptical contours of themain span’s massive twin piers provide aesthetic appeal, the shape wasprimarily chosen because it best fulfilled the design mandate of a structure able to withstand sustained hurricane force winds of up to 240 milesper hour (386 km/hr). This projectwon a PCI Design Award in 1987.

Natchez Trace Parkway Arches

The graceful Natchez Trace Parkway Arches near Nashville, Tennessee, completed in 1994 at a cost of$11.3 million, is America’s only precast concrete segmental arch bridge.The 582 ft (177.4 m) main span issymmetrical, while the 462 ft (140.8m) second span is asymmetrical.Depths of the precast box girder superstructure vary from 7.5 ft (2.3 m) atmicispan to 14.33 ft (4.4 m) at thepiers. The side slopes of the trapezoidal box are constant, resulting in avariable-width soffit.

While these diverse geometries provide a stunning finished product (see

Fig. 6. The impecably beautiful Natchez Trace Parkway Arches is America’s first useof precast concrete segmental technology for an arched structure. It was completedfor $11.3 million in 1994.

30 PCI JOURNAL

Fig. 6), the design presented challenges requiring creative solutions bythe FlOG designers and the builder,PCL Civil Constructors. In selectingthe Parkway Arches for the 1994 Portland Cement Association Award ofExcellence, the jury commented,“.. .the clean and simple, yet elegantand functional arches fit gracefullyinto the rural setting.. .one can feel theflow of forces in this structure withouthaving to do any [structural] analysis.”

STRENGTH ANDD U RAB IL I TY

Dauphin Island Bridge

Precast concrete segmental bridgeshave repeatedly proved their strengthand endurance when tested by extremenatural forces. For instance, since its1982 completion, the Dauphin IslandBridge near Mobile, Alabama, haswithstood five hurricanes and severetropical storms without damage (seeFig. 7). The 17,814 ft (5429.7 m) longbridge replaced a conventional bridgedestroyed by Hurricane Frederick in1979. Under the owner’s mandate forrapid design and construction, the $32million replacement structure was finished in just 34 months.

The center span of the 822 ft (250.5m) main span is 400 ft (121 m) long,

an American record at the time forprecast segmental balanced cantileverconstruction. Brown & Root erectedthe three continuous main spans,which vary in depth from 7 ft (2.1 m)at midspan to 21.42 ft (6.53 m) at thepiers. Twin-walled 1-shaped piershelped to counter the unbalancedloads on the foundations during construction. The bridge’s higher levelhas twenty-six 118 ft (35.96 m) spansbuilt span-by-span on vertically post-tensioned, hollow precast concretesegmental box piers. This bridge wona PCI Design Award in 1983.

Varina-Enon Bridge

A good demonstration of the durability of precast concrete segmental construction is the Varina-Enon Bridgethat carries six lanes of Interstate 295over the James River southeast ofRichmond, Virginia. In August 1993, atornado directly hit the 630 ft (192 m)cable-stayed main span. Althoughtrucks traveling across it were overturned, the bridge sustained no damage.

The sturdy structure, completed in1990 by S. J. Groves Construction at acost of $34.4 million, featured the

Fig. 8. The VarinaEnon Bridge nearRichmond,

] Virginia, featuresthe world’s first useof precast concretedelta frames forconstruction of its630 ft(192 m)cable-stayed mainspan. This elegantand durablestructure sustaineda direct tornadoimpact withoutdamage.

Fig. 7. The Dauphin Island Bridge in Mobile, Alabama, was built in just 34 months,featuring a 400 ft (122 m) main span — the longest precast concrete segmental spanat the time of completion in 1982.

September-October 2004 31

first-ever use of precast concrete deltaframes to help support the main span’stwin parallel segmental box girders(see Fig. 8). The innovative deltaframes allowed the cable stays to hearranged in an aesthetically pleasingsingle plane and the superstructure toremain the same size from abutment toabutment, saving construction timeand equipment costs.

Named one of the “Twelve MostSpectacular Bridges in America in1995” by the American Council ofEngineering Companies, its 300 ft(91.4 m) tall single pylons and singleplane of stays support the main spanwith 147 ft (44.8 m) of vertical navigation clearance. The approach spans

[150 ft (45.7 m) typical length] wereconstructed span-by-span up to themain pylon, permitting the main spanto he constructed in unidirectionalcantilever. Precast concrete segmentswere used for the piers. bridge deck,cable towers and delta frames.

SPAN LENGTHS INCREASE

Sagadahoc Bridge

As materials and construction technologies have advanced, so have thelengths of precast concrete segmentalmain spans using balanced cantilevererection (see Fig. 9). The 400 ft (121m) record of the Dauphin Island

Bridge was broken in 2000 by theSagadahoc Bridge in Maine.

Carrying U.S. Highway I trafficover the Kennebec River betweenBath and Woolwich, the main span ofthis $46.6 million bridge is 420 ft (128m) long. Each of the two-cell precastbox girder segments, erected by Flatiron Structures, is 69 ft (2 I m) wideand varies in depth from 9.17 (2.8 m)at midspan to 19.58 ft (5.97 m) at thepiers, and weighs up to 100 tons (91tonnes).

Victory Bridge

In 2004, the record for a balancedcantilever span length in America wasbroken again. With a fully match-cast,precast concrete main span of 440 ft(134.1 in), the current record holder isthe new twin-span Victory Bridge innorthern New Jersey. The 3971 ft(1210 m), $109 million precast concrete segmental bridge will carry traffic 110 ft (33.5 m) above the RaritanRiver between Perth Amboy andSayreville, replacing a 1927 steelswing bridge (see Fig. 10).

Built in stages by George HarmsConstruction, the second of the twinspans will be constructed at the location of the old bridge. VictoryBridge’s final span is scheduled forcompletion in 2005, less than threeyears from the start of construction.To expedite construction speed, theapproach spans are being erectedspan-by-span, simultaneously with thebalanced cantilever main span.

Fig. 9. Sagadahoc Bridge in Maine has a 420 ft (128 m) precast segmental main spanand was completed in 2000. Precast concrete segments weighed 100 tons (91 tonnes).

Fig. 10. The 440 ft (134 m) precast fully match-cast main span of the Victory Bridge in northern New Jersey was dedicated onJune 5, 2004; the twin span is scheduled for completion in 2005.

32 PCI JOURNAL

CONGESTED URBANCORRI DORS

A significant and growing competitive advantage of precast concrete segmental construction is its ability to beconstructed in congested urban corridors, with erection next to or over traffic — with minimal transportation delays or detours.

In addition to the Lee Roy SelmanCrosstown Expressway project discussed above, other applications ofthis innovative design solutioninclude:

Interstate 110, a 7.8 mile (12.6km) elevated connection betweenInterstate 10 and U.s. 90 in Biloxi,Mississippi — This elevated roadwayopened in 1988 after construction byHarbert International and DementConstruction with a bid of $29.6 million (see Fig. ii). The Interstate 110infrastructure was the first use of themodified balanced cantilever methodof construction and was the recipientof the PCI Award of Excellence in1989.

Interstate 10 and Interstate 35“Y” bridges in San Antonio, Texas —

Prescon Corporation and AustinBridge Company completed the 1.3million sq ft (120,770 m2) of bridgework in 1989, with a bid of$65.4 million, or about $8 million less than thecompeting design (see Fig. 12).

Illinois Toliway Interchange between the North-South and East-West Tollways in Chicago, Dllnois —

Completed in 1989 by Paschen Constructors, the 186,000 sq ft (17,279m2) interchange presented complexalignments with tightly curved geometry (see Fig. 13). The precast concretesegmental box girder structures bidwas $10.3 million, saving $4.5 millionover the alternate design.

Interstate 93 ramps and viaduct,part of the Central Artery project inBoston, Massachusetts — Built byModern Continental in 2003, the $79million project totaled about $27 million less than the competing solution.This interchange has the smallest radiiand tightest horizontal curvature —

only 212 ft (64.6 m) — of any precastconcrete segmental bridge in theUnited States (see Fig. 14).

Fig. 13. TheIllinois ToliwayInterchange, nearChicago, Illinois,demonstrates thatsegmentalconcretestructures can bebuilt over majortraffic flows.

Fig. 11. Biloxi 1-1 10 in Mississippi was built over the four-lane U.S. 90 to minimizetraffic interruptions. $4.2 million was saved over the alternate construction system atthe time of bidding.

L z.Fig. 12. The San Antonio, Texas, “Y” bridges, built in the existing right-of-way(downtown 1-10 and 1-35), exemplify the value of precast concrete segmental bridgesfor construction in extremely restricted urban areas while maintaining traffic flow.

September-October 2004 33

New Strand Cradle System —

Maumee River Bridge

An outstanding illustration of innovation in precast concrete segmentalbridges, presently under construction,is the Maumee River Bridge in

Toledo, Ohio, that will carry Interstate280 with a unique cable-stayed structure (see Fig. 15).

The top 190 ft (57.9 m) of the 435 ft(132.6 m) pylon is clad with speciallyengineered glass on all four sides, and

will be illuminated by internal LED(Light Emitting Diodes) spotlights thatcan produce a virtually unlimited arrayof vivid colors. This dramatic aesthetic feature of the bridge (see structure below) was selected by the participants of community design workshops as a tribute to the heritage of thearea’s glass industry.

To accommodate the desired slendershape of the pylon and single plane ofstays, FIGG designed a first-of-its-kind cradle system to carry the staysthrough the pylon, thus eliminatingpylon anchorages. As a result, the cables supporting the 1225 ft (373.4 m)main span will contain as many as 156strands — 70 percent more than anypreviously used on a bridge.

Extensive testing of the new cradlesystem verified that the cable strandswould move through the cradle independently, even when subjected tomore than 3000 times the projectedloads on the stays. The cradle systemwill also facilitate inspection andmaintenance by permitting easy removal and replacement of the strandsto monitor their condition throughoutthe life of the bridge.

--

---

t-h:

‘— -

______ _________

“

Fig. 15. Displaying patriotic colors, this dramatic night photo of the 1-280 Maumee River Crossing in Ohio illuminates a newToledo landmark. Specially engineered, the top 190 ft (57.9 m) of the single pylon is glass-clad, a community tribute to its glassindustry. A first-of-its-kind cradle system carries the cable stays through the central pylon.

Fig. 14. An aerial view of the 1-93 ramps illustrates traffic congestion all-to-familiarto Boston, Massachusettes, commuters. Horizontal curvature as small as 212 ft (64.6m) and other precast concrete design advantages saved the Massachusetts TurnpikeAuthority over $27 million at the time of bidding.

34 PCI JOURNAL

Constructed by Fru-Con, the $220million project includes 2.75 miles

(4.43 km) of ramps, roadway andbridge, and 1.2 million sq ft (111,480m2) of bridge deck. The 12 ft (3.7 m)deep segments of the main span willbe constructed in balanced cantilever.Ramps and approaches will be erectedspan-by-span. There will be 108 rampand approach spans, ranging in lengthfrom 106 to 151 ft (32.3 to 46.0 m).This landmark structure is scheduledfor completion in 2007.

RAIL TRANSIT BRIDGES

The MARTA

Precast concrete segmental construction has also been used for railwaybridges, both mass transit and heavyrail lines. The first use in the UnitedStates of segmental bridges for passenger rail lines was completed in 1983 forthe Metropolitan Atlanta RegionalTransit Authority (MARTA) in Georgia. Constructed by J. Rich Steers for$30.9 million, the two bridges total7130 ft (2173 m) with span lengths between 70 and 143 ft (21.3 and 43.6 m).

The 7 ft (2.1 m) deep precast segments are 30 ft (9.1 m) wide and carrytwo tracks (see Fig. 16). The first segmental bridge project to use twin thangular trusses under the wings to supportthe box girder during span-by-spanerection, the MARTA line resulted inthe maximum vertical clearance forconstruction over traffic. This projectwon a PCI Design Award in 1985.

The JFK AirTrain

The AirTrain is another passengertrain segmental bridge built over traffic at New York’s John F. KennedyInternational Airport, and opened in2003. Providing convenient access tosix airport terminals, parking areas,and the Jamaica Station transportationhub, the facility has 9 miles (14.5 kin)of superstructure — with over 5409precast concrete segments, the most ofany segmental bridge in America.

About 3 miles (5 km) of the elevated structure was erected in the narrow 10 ft (3.1 m) median of the verycongested, six-lane Van Wyck Expressway. The JFK AirTrain is a

major design/build/operate/maintainproject, undertaken by the AirRailTransit Consortium. Erection of thesuperstructure was completed by KochSkanska.

Fig. 16.Completed in1983, the firstprecast concretesegmental bridgesbuilt for railwayuse in the UnitedStates weredesigned for theMetropol tanAtlanta RapidTransit Authority(MARIA) inGeorgia.

The 10 ft (3.1 m) deep precast concrete segments are 19.25 ft (5.87 m)wide for the one-rail guideways and31 ft (9.5 m) wide for the two-railguideways. Weighing up to 25 tons

_______

- - -J 4 =- -

-\\ g -

______

- .

-

_____

-_/;,

__

4

_______

__0 —

c‘i’’ ‘--‘rFig. 1 7. AirTrain, New York’s John F. Kennedy International Airport passenger train,proudly opened 9 miles (14.5 km) of precast concrete segmental bridge transport tothe public in 2003. Within the confines of a narrow right-of-way, the AirTrain risesabove the six-lane Van Wyke Expressway.

September-October 2004 35

Fig. 18. The John T. Collinson Rail Bridge near Pensacola, Florida, is the first use ofprecast concrete segmental technology for a heavy rail bridge in North America. Thebridge is designed to handle the heaviest train loadings, hurricane force winds, andbarge impacts.

Fig. 19.Completed in

1995, theChesapeake &

Delaware CanalBridge near St.

Georges,Delaware, wasthe first precastconcrete cable-stayed bridge in

the northeastUnited States.

Using innovativedesign solutions,including precast

concrete deltaframes, this bridge

delivered asavings of $6.2

million overalternate bid

designs.

(22.7 tonnes) each, they were fabricated in Cape Charles, Virginia byBayshore Concrete Products Corporation. Segments were barged 250 miles(402 km) to New Jersey and thentrucked 100 miles (161 km) to the site.Nearly all of the precast concrete segments are individually unique so as toaccommodate the complex curvatureof the bridge project.

This won the 2003 PCI DesignAward for Best Non-Highway Bridge(see Fig. 17). The American RailwayEngineering and Maintenance Association also honored the JFK AirTrainproject with the 2003 Dr. W. W. HayAward for Engineering Excellence.

John T. Collinson Rail Bridge

The first segmental bridge for heavyrail in America was the John T.Collinson Bridge over Escambia Baynear Pensacola, Florida. Completed in1988, it is part of the CSX Transportation line between Jacksonville, Floridaand New Orleans, Louisiana, and wasdesigned to withstand the full weightof the heaviest train loading (CooperE90 rating). The rail bridge ws alsodesigned to resist hurricane forcewinds, as well as a 1400 kips (6228kN) barge impact force on the navigation channel piers (see Fig. 18).

Over two miles (3.2 km) long, thebridge rises on a one percent grade toa 50 ft (15.2 m) vertical clearance overthe channel. The 370 ft (113 m) mainspan was erected in modified balancedcantilever, using triangular trusses forthe back span. The piers are precastconcrete boxes assembled with vertical post-tensioning.

Economical, efficient, durable, versatile, constructable (in confinedspaces and over traffic), and environmentally sensitive — these valuablebenefits have allowed precast concretesegmental construction to make a remarkable contribution to the U.S.bridge industry. But what has madesegmental bridges an enthusiastic favorite of the communities they serve isthe intrinsic beauty of their shapes.

ART IN STRUCTURE

The following bridges are just twoexamples of such works of art.

36 PCI JOURNAL

Fig. 20. BroadwayBridge in DaytonaBeach, Florida, wascompleted in July2001. Twin segmental bridges crossover 3000 ft (914 m)of the IntercoastalWaterway. Based oncommunity input,the bridge featureselliptical piers and262 ft (79.9 m) longprecast segmentalspans.

Chesapeake & DelawareCanal Bridge

A spectacular example of the graceand beauty of precast concrete structures is the majestic Chesapeake &Delaware Canal Bridge in St. Georges,Delaware (see Fig. 19). This cable-stayed precast concrete segmentalbridge — the first of its kind in thenortheastern United States — is a signature landmark of the region. Its slender profile and unobtrusive substructure, coupled with its dramaticcable-stay arrangement, is widely acclaimed. This innovative bridge designearned PCI’s prestigious Harry H. Edwards Award in 1995.

Completed in 1995 by RecchiAmerica (now Condotte America), the$58 million bridge showcased precastconcrete technology that resulted in a$6.2 million savings over the alternatedesign. The superstructure was anearly application of precast deltaframes, an innovation that simultaneously helps support the box girders ofthe 750 ft (229 m) main span and provides anchorages for the visually appealing single plane of stays. The 150ft (45.7 m) approach spans wereerected span-by-span on precast concrete box piers as quickly as one spanevery four days. The main span wasconstructed in unidirectional cantilever without interference to shipsnavigating the canal 138 ft (42.1 m)below.

The precast segments were produced by Bayshore Concrete ProductsCorporation in Cape Charles, Virginia,and shipped to the bridge site bybarge.

Broadway Bridge

Community preference for structures that become enduring works ofart was evidenced by the DaytonaBeach, Florida, residents who participated in design workshops for the

Fig. 21. Artisticglass mosaics onthe BroadwayBridge piersdisplay manateesand leapingdolphins,reflecting thestructure’s“TimelessEcology” theme.

Broadway Bridge over the HalifaxRiver. Through public consensus, byvoting on affordable aesthetic features, local citizens selected detail elements reflecting the design theme of“Timeless Ecology.”

September-October 2004 37

Fig. 22. An artist’s rendering ofthe proposed Indian River InletBridge, in Delaware’s SeashoreState Park, captures the intrinsicbeauty ofa 1000 ft (305 m)precast concrete arch cable-stayed span.

Colorful glass mosaic tile designs ofwildlife indigenous to the Atlanticcoast enrich the visual experience ofbridge passengers and pedestrians. Finally, mosaic murals of dolphins andmanatees wrap around the 26 piers(see Fig. 20).

The $37 million project, completedin 2001 by Misener Marine, has twinparallel structures with a total deckarea of 260,152 sq ft (24,168 m2). The352 precast segments, 48 ft (14.6 m)wide and 13 to 7.75 ft (4.0 to 2.36 m)deep with span lengths of 262 ft (79.9m), create a graceful and timelessarching expanse (see Fig. 21).

THE FUTURE FOR PRECASTSEGMENTAL BRIDGES

So, after presenting numerous examples of a dynamic tradition of con-

tinuously advancing technology andaesthetics, what type of future awaitsprecast concrete segmental bridges inAmerica? With the following glimpse— a glowing one!

Indian River Inlet Bridge

Consider the novel Indian RiverInlet Bridge in the Delaware SeashoreState Park slated for construction bidsin early 2005 (see Fig. 22). The designtheme selected in community workshops for this 1000 ft (304.8 m) cable-supported concrete arch span is “Harmony with Nature.”

Rising out of a dune-like, land-based substructure, the organic curvesand colors of the tulip-shaped archwith its radial plane of stays will create the impression that this bridgemight, indeed, be “born of the earth.”

At night, the stays will glow with soft,blue hues, silhouetting the arch as adistinctive beacon for mariners seeking the inlet gateway.

The Indian River Inlet Bridge andother precast concrete structures presented here are magnificent beaconstoward a future of continuing innovation in design and untapped aestheticpotential that excites the imagination.More than any other construction type,precast concrete segmental bridgesprovide an unequaled opportunity tomarry engineering and art, the utilitarian and the ethereal, and intellect withthe human spirit.

The fruit of such unions are elegant,functional sculptures that inspire universal feelings of awe and admiration.The future of precast concrete segmental bridges is indeed bright.

38 PCI JOURNAL

ADDENDUMPERFORMANCE OF SEGMENTAL CONCRETE BRIDGES

IN 2004 HURRICANE SEASON

On September 16, 2004, Hurricane Ivan roared ashoreon the Gulf coast, near Mobile, Alabama and Pensacola,Florida. It came ashore as a strong Category 3 storm withwinds up to 130 miles per hour (210 kin/br). According tothe National Oceanic and Atmospheric Administration(NOAA), hurricane strength winds spread over a 160-mile(257 km) wide area, with storm surges as high as 30 ft(9 rn) recorded on Pensacola Bay. east of the storm’s eye.

The following concrete segmental bridges stood strongdespite a direct hit of Hurricane Ivan, with no structuraldamage:

• Dauphin Island Bridge over the Intracoastal Waterway[17,814 ft (5430 m) in length], connecting to a barrierisland near Mobile, Alabama(owned by Alabama Department of Transportation)

• Cochrane Bridge in Mobile, Alabama[1500 ft (457 m) cable stayed bridge](owned by Alabama Department of Transportation/FIGGDesign check/CEI)

• John T. Collinson Bridge over Escambia Bay[11,370 ft (3465 m) length I. Pensacola, Florida(owned by CSX Railroad)

As four hurricanes have pounded Florida’s coastlines inthe record-setting 2004 hurricane season, segmentalbridges have proven to be strong and durable during extreme wind conditions, including:

• Garcon Point Bridge over Pensacola Bay[18,425 ft (5616 m) length], east of Pensacola, Florida(owned by Santa Rosa Bay Bridge Authority)

• Broadway Bridge[3008 ft (914 m) Iengthj, over the Intercoastal Waterway,

Daytona Beach, Florida —

Hurricane France.r, Category 2, September 5 andHurricane Jeanne, Category 3, September 26

• Mid-Bay Bridge over Choctawhatchee Bay[19,265 ft (5872 m) length], between Nicevilleand Destin, Florida(owned by Mid-Bay Bridge Authority)

• Sunshine Skyway Bridge over Tampa Bay, Florida —

11200 ft (366 iii) length]Tmpical Storm Frances (winds to 70 miles per hour(113 kmlhr), September 5 andHurricane Jeanne, Category 1, September 26

September-October 2004 39