AASHTO-PCI-ASBI Segmental Box Standards: A New Product for Grade Separations and Interchange

With the introduction of the soon to be ratified AASHTO-PC/-ASBI Segmental Standards, precast, prestressed producers have the opportunity to more fully participate in the segmental market, which is estimated to have an annual construction volume of about one billion dollars in North America. The purpose of this article is to provide background material on the segmental standards, to review past segmental grade separation and interchange projects both in this country and around the world, and Clifford L. Freyermuth to present future prospects for construction. The Manager general consensus is that segmental construction, in its various forms, American Segmental Bridge Institute holds a viable and promising future for the precast concrete industry. Phoenix, Arizona

Clifford L. Freyermuth is president of t is estimated that since 1980, the Continued growth in the use of seg­ Clifford L. Freyermuth, Inc., which was cost of segmental construction (pre­ mental concrete bridges during the fol­ formed in 1988 to provide structural consulting se rvices for post-tensioned, Icast and cast-in-place) completed in lowing 12 years led to the formation buildings and bridges. North America is about $5 billion. of the Joint PCI-ASBI (Precast/ The firm has provided manage ment and Today, the annual construction volume Prestressed Concrete Institute-Ameri­ technica l services to the Ameri ca n of this industry is around $1 billion and can Segmental Bridge Institute) Com­ Segmenta l Bridge Institute (ASBI) since 1989. is expected to grow in the next century. mittee in 1994 with the mission of de­ Mr. Freyermuth's prior experience includes 12 yea rs as manager of the Post-Tensioning In July of 1982, the Federal High­ veloping standard precast segmental Institute (PT I), 5 yea rs as director of the Post­ way Administration (FHW A) pub­ box girder sections for grade separa­ Tensioning Division of the Prestressed lished a research report developed by tion and interchange bridges with Concrete Institute (PCI ), 6 years with th e T. Y. Lin International titled "Feasibil­ spans of up to 61 m (200ft). Portland Ce ment Associat ion (PCA), and 6 ity of Standard Sections for Segmental The first meeting of the PCI-ASBI yea rs as a bridge engineer for th e Arizona Highway Departm ent. He has bee n Prestressed Concrete Box Girder Joint Committee was held in October responsible for th e development of several Bridges."' This report concluded that 1994 at PCI Headquarters in Chicago. committee repo rts and manuals related to the "development of standard sections Development of the proposed standards segmental concrete bridges. for segmental prestressed concrete box by the 19-member committee (includ­ girder bridges is feasible and can be ing representatives of AASHTO, immediately initiated. However, the FHW A, PCI and ASBI) was completed range of sections and related items to with submission of the proposed be standardized should be prescribed "AASHTO-PCI-ASBI Segmental Box and somewhat limited." Girder Standards for Span-by-Span and

32 PCI JOURNAL Fig. 1. 1-75/1-595 Interchange, Broward County, Fl orida. This four-leve l fully directional interchange is the largest interchange in the state of Flori da. Th e bridge stru ctures are composed of curved precast concrete segmental box erected by th e balanced ca ntilever method (Des igner: Be iswenger Hoch & Assoc iates).

PCI-ASBI JOINT COMMITTEE

CLIFFORD L. FREYERMUTH, Co-Chairman CHUCK PRUSSACK, Co-Chairman American Segmental Bridge Institute Central Pre-Mix Prestress Company Phoenix, Arizona Spokane, Washington

ROY ALLEN JAMES R. HOBLITZELL JOE ROCHE Symons Corporation Federal Highway Administration Prestress Services of Kentucky, Inc. New Braunfels, Washington, D.C. Lexington, Kentucky VINCENT CAMPBELL JAMES D. LOCKWOOD Q. D. SPRUILL, JR. Bayshore Concrete Products J. Muller International Gulf Coast Pre-Stress, Inc. Cape Charles, Virginia Chicago, Illinois Pass Christian, Mississippi REID W. CASTRODALE ALAN MATEJOWSKY MAHER K. TADROS Ralph Whitehead Associates Texas Department of Transportation University of Nebraska at Lincoln Charlotte, Austin, Texas Omaha, Nebraska JOHNCORVEN R. KENT MONTGOMERY TEDDY THERYO DMJM Figg Engineers, Inc. Parsons Brinckerhoff Tallahassee, Florida Denver, Colorado Tampa, Florida JOHNS. DICK WARREN H. MOSES JOSEPH K. TSE Precast/Prestressed Concrete Institute Bayshore Concrete Products DRC Consultants, Inc. Chicago, Illinois Cape Charles, Virginia Flushing, New York

G. L. ENGELHART JERRY L. POTTER Engelhart & Company Florida Department of Transportation Baton Rouge, Louisiana Tallahassee, Florida

September-October 1997 33 t--- Symm. Nxlut £ Girder NOTES, Vorle.s from 8,400 to 11,400 I. keo derotes cross- sectional or eo.

I 2. Wt denotes segment we/ott for JfXXJ mm 'A' 4,200 1.361 1.200 r-:- 269 1.310. 'A' segment. I .,iii iil ., 3. lx deoo/es bending moment or Inertia. ~ ~ I ~ / 4. Yf deootes dlsfollC8 from tte centro/dol axis to tte top of SfJCflon. ~ 'IT 400 R 200R :;~ 5. If For widths less !ton 8,400 mm.the 1.310 mm dlmen.slon Is decr(K]sotf. The de{Jih or the slob ot the edge or ~ 2~v ~2~ the segment lncreoses occcrdlngty. (\j tE I 2400-1 Deck Width 'A' Area Wt/ JIJOO mm lx Yt ~ ~ I lmml l mm! fmm 2J (KnJ (m "J lmm/ 8.400 0 4, /47/)()() 304 3.366 842 I 8700 I SO 4.214/)()() 308 3.402 830 I 9/)()() 300 4.282/)()() 313 3.437 819 I 9.300 450 4.349/)()() 318 3.470 BOB 2JJIO IIJ2t 189 9.600 600 4.4 /7/)()() 323 3~2 797 9/]00 750 4.484/)()() 328 3~34 787 4[)20 10.200 900 4.552000 333 3~5 m 10.500 1[)50 4.619/)()() 338 3~94 767 2..iQ.Q.:j 101!00 I .ZOO 4,667/)()() 343 3.623 758 11.100 1.350 4754/)()() 348 3.65t 749 t--- Symm. AJxxJt £ Girder 11.400 1.500 41!22/)()() 353 3.678 740

Varies f rom 10~ to 13.500 I 'A' 5.400 1.607 1.500 323 19 70 'A' I ~ ~ ~ I ~ ~I r-r---, / I 1--' / "\r ~ r 400R "" 200 R I I I 2400-2 Dect Width 'A' Areo Wf/JIXJO mm lx Yl ~ 2~v ~ 2~ lmm! fmmJ fmm 2J IKn! rm "J l mm! "' ~rf)_ 101!00 0 5.256/)()() 385 4.303 836 I lf./00 /50 5.323/)()() 390 4.339 827 11.400 300 5.39//)()() 395 4Jl3 818 ~~ I 117 00 450 5.458/)()() 400 4.406 809 12/)()() 600 5,526/)()() 404 4.439 801 12.300 750 5.593/)()() 409 4.471 792 I I 12.600 900 5.661/)()() 414 4~2 784 1[)50 5728/)()() I 12/]00 419 4~32 776 13.200 I .ZOO 5.796/)()() 424 4~2 769 2.610 2.367 243 f----- 13.500 1.350 51!63/)()() 429 4~91 761 5.220 2±Q.Q..:..2

PROPOSED AASHTO - PCI - ASBI FOR SPAN-BY-SPAN CONSTRUCTION 2400 mm "U Q SEGMENTAL BOX GIRDER STANDARDS SPANS 30.5 TO 45.7 METERS SEGMENT DEPTH c... 0 c :Ilz F= Fi g. 2. Sta ndard section: 2400 mm (8 ft) segment depth for span-by-spa n construction. (J) C1l "'0ro 3 c:r C1l r-- Symm. l>baJI £ Girder 6 Varies from 8.400 to 11,400 2400-1 I Deck Wldfll ' A' Area Wt/3.000 mm IX Yf s 'A' 42UJ 1.201 1200 377 1,422fflf 'A' 2 c:r lmm/ fmmJ fmm J fKnJ tm"'J lmmJ ~ I 8,400 0 5,1T7/)()() 379 41)64 908 8100 150 5245.000 384 4.107 898 (0 I 5.3/2/)()() 4.148 (0 ~ I 9.000 JOO 389 888 -..J 9.300 450 5.380/)()() 394 4.188 878 I 9/iOO 600 5,447.000 399 4228 869 1=1 9!JOO 750 5515/)()() 404 4266 859 ¥tr-:1-- 5582.000 409 4.304 850 I 900 400R 200 R ~IOSOO 1.050 5£,50/)()() 414 4.340 841 10.800 1200 5117/)()() 4/9 4.376 833 2su 4.411 824 ~ 3'fJ. j25 11.100 1.350 5185.000 423 "" 11.400 I SOD 5.852.000 428 4.445 816 "900 ~~ I lt(IN! ~ I -- _1 N(ff£5, I 1. Area denotes cross-s6CIIonol oreo. Kl~ I ..~! I -- 2. WI denotes segment welgtt for 3000 mm segment. 2,0/0 _j 1.813 197 3. lx denotes bending rooment of Inertia. 4.020 4. rt denotes distance from the centro/dol 2.!.Q.Q:J axis to the top of secl1011.

r-- Symm. l>baJI £ Girder 5. * Bottom slob ttictncss may /!'K;I'ecse Varies from IOJJOO to 13.500 to a rnoxlrrum of 450 mm at piers. 900 mm dimension adjusts occordlngly I 'A' 5.400 1.474 I SOD 404 2.022 ' A' - 5. IHf For wldfhs less th:m 8.400 mm, fie I 1.422 mm dimension Is decreased. "' T/'e deptll of 1/'e slab at t/'e edl}t: of ~ ~I I tte segmenllncreases occordlngly. I 1 I 400R ZOOR ==;i-1 I 2400-2 'A' 5f5 I 25 Deck Wldtll Area Wf/3.000 mm lx Yf 25v j lmmJ lmmJ fmm 2 J fKnJ tm "' J lmmJ ~ I 10.800 0 6.327.000 463 5.D45 882 I '900 ~~ I 11100 /50 6.395.000 468 5.()85 874 '11;1.'.1 11,400 6,462.000 473 5.124 ~ ~ I 300 866 --- _I i 11100 450 6530.000 478 5.162 858 12.000 600 6597.000 483 5.199 851 12.300 750 6£,65.000 488 5236 843 I ---- 121500 900 6132.000 493 5272 836 ~~ 498 ~"'" - I 12!JOO 1.050 6.800.000 5.307 829 13200 1200 6.867.000 503 5.342 821 2£,10 2.386 224 i 13SOO 1.350 6.935.000 508 5.376 815 5220 2.iQQ:.2

PROPOSED AASHTO - PCI- ASBI FOR BALANCED CANTILEVER CONSTRUCTION 2400 mm SEGMENTAL BOX GIRDER STANDARDS SPANS 30.5 TO 61.0 METERS SEGMENT DEPTH

w (.11 Fi g. 3. Standard section : 2400 mm (8ft) segment depth for ba lanced canti lever construction. providing quotations on both of the alternatives. The purpose of this article, as re­ flected in the following sections, is to provide background material on the segmental standards, to review past segmental grade separation and inter­ change projects in both the United States and other countries, and by use of current or proposed projects, to il­ lustrate the present reality of the mar­ ket for use of the segmental standards. It is fervently hoped that this article will encourage owners, designers, pre­ cast producers, and contractors to uti­ lize the segmental standards as a vi ­ able and attractive construction option for grade separation and interchange Fig. 4. Span-by-span erection, U .S. 183 , Austin, Texas (Designer: Texas bridges in the next century. Department of Transportation). SCOPE OF THE SEGMENTAL STAN DARDS The 17 sheets of standard drawings include: • General Notes • Three drawings for span-by-span segments with depths of 1800, 2100 and 2400 mm (6, 7, and 8ft) • Five drawings for balanced can­ tilever segments with depths of 1800 through 3000 mm (6 through 10 ft) in 300 mm (1 ft) increments • Two drawings of standard bulkhead details • One drawing of deviation diaphragm dimensions • Two drawings of interior pier seg­ ment dimensions • One drawing of expansion joint seg­ ment dimensions Fig. 5. Balanced cantilevers under construction at U.S. 441 /1-595 Interchange • One post-tensioning layout drawing (Des igner: Greiner Engineering Sciences, Inc.) . for span-by-span construction As examples, Fig. 2 shows one of Balanced Cantilever Construction" to The rationale for the use of precast the standard drawings for span-by­ the AASHTO Subcommittee on segmental bridges for grade separation span construction and Fig. 3 shows Bridges and Structures in September of and interchange bridges (see Fig. 1 ), one of the standard drawings for bal­ 1996. and the importance of involvement of anced cantilever construction. The proposed standards were ac­ the precast concrete industry, is out­ The standards provide sections ap­ cepted as an item for the official ballot lined in the accompanying editorial by plicable for span-by-span bridges with at the 1997 meeting of the AASHTO ASBI President, Eugene C. Figg, Jr. spans ranging from 30.5 to 45.7 m Subcommittee on Bridges and Struc­ The box girder standards are viewed (100 to 150 ft). For balanced can­ tures, held June 8 to 12 in Jackson, as a means of extending the bridge tilever bridges, the standard segments Wyoming. It is anticipated that the market for precast concrete producers, are intended for spans ranging from proposed standards will be approved and not as a product competing 30.5 to 61.0 m (about 100 to 200 ft). in the official AASHTO balloting in against existing !-girder and bulb-tee For both span-by-span and balanced the Fall of 1997. When ratified, a joint sections. In the limited range of appli­ cantilever bridges, standard segment publication of the standards and re­ cations where competition might exist widths range from 8.40 to 13.50 m (27 lated information by PCI and ASBI is between sections, precast producers to 44 ft). The span and width dimen­ planned for early 1998. would be in the enviable position of sions of the standards were selected as

36 PCI JOURNAL 0

~ I

FINAL PRESTRESS

Fig. 6. Segmental erection stages used in construction of Rhone-Aips Motorway Overpasses, Switzerland, 1970s. representative of a large majority of COMPLETED GRADE 150 overpasses over a 5-year period. 2 the potential superstructures for which SEPARATION AND These bridges were typically three­ use of standard sections might be span structures with main spans rang­ INTERCHANGE PROJECTS appropriate. ing from 18 to 30 m (60 to 100ft). The segmental standards have been One of the earliest and largest appli­ The construction procedure for these developed to accommodate span-by­ cations of precast segmental construc­ bridges is shown in Fig. 6. 3 The total span or balanced cantilever erection of tion to shorter span bridges occurred construction time for a single overpass segments. Span-by-span erection is in the 1970s with construction of the (foundations, piers, and superstruc­ shown in Fig. 4 and balanced can­ Rhone-Alps Motorway in Switzerland. ture) using this technique was less tilever erection is illustrated in Fig. 5. This project involved construction of than 2 weeks. The segment dimensions were de­ veloped to be compatible with the heavier live load requirements of the ,, AASHTO LRFD Specifications. The recommended minimum concrete strength is 34 MPa (5000 psi). Con­ crete of greater compressive strength may be used and may be required for structural considerations in some cases. To facilitate truck delivery of pre­ cast segments, the maximum length is 3000 mm (10ft) and the maximum weight is 356 kN (80,000 lbs). The length of the larger segments has to be reduced to meet the 356 kN (80,000 lbs) weight limitation. It is generall y anticipated that the segments will be erected by crane. Fig. 7. Ayalon Interchange construction, Israel, 1995 .

September-October 1997 37 Precast segmental technology has been widely used in the 1990s outside of North America for the construction of grade separation and interchange bridges. Construction of the Ayalon In­ terchange in Israel (1995) is shown in Fig. 7. In this case, the structure was erected using an overhead gantry. As il­ lustrated in Fig. 7, this type of erection involved minimal disruption of traffic. A portion of the Second Stage Ex­ pressway System in Bangkok, Thai­ land (1995), that incorporates an inter­ change is shown in Fig. 8. This project included 1130 precast segmental spans ranging in length from 24.9 to 48.7 m (82 to 160ft) with a typical span Fig. 8. Second Stage Bangkok Expressway System, Thailand, 1995 (Designer: j. length of 45 m (148 ft). If placed Muller International). along a single alignment, the 1130 spans would produce a length of ap­ proximately 48 km (30 miles). Construction was completed on a series of four precast segmental bridges on Interstate 70 west of Den­ ver, Colorado, at Vail Pass in 19763 (see Fig. 9). The lengths of the bridges ranged from 119 to 253 m (390 to 830 ft), and the main span lengths were ei­ ther 61 or 66 m (200 or 210 ft). A sin­ gle-cell box section was used for the 12.8 m (42ft) wide segments. Twenty-five precast segmental grade separations and interchange bridges were constructed in Florida in the 1980s.• These were balanced cantilever bridges with spans ranging from 22 to Fig. 9. Precast segmental construction at Vail Pass, Colorado, 1976. 68 m (71 to 224 ft). The total deck area of these structures was about 130,000 m2 (1,400,000 sq ft). The average cost of these bridges (1987) was $559 per m2 ($52 per sq ft). As illustrated by Figs. 10 and 11 , many of these bridges were constructed on curved roadway alignments. The I-ll 0 bridge in Biloxi, Missis­ sippi (see Fig. 12), was opened to traf­ fic February 19, 1988.; The 1626 m (5332 ft) long mainline structure pro­ vides four traffic lanes and crosses U.S. 90 with 49 and 55 m (160 and 180ft) spans. The same box girder depth was used throughout the superstructure, and the cast-in-place piers were given a special rustication. Ramp structures were also effectively incorporated into the system. The balanced cantilever precast segmental superstructure was Fig. 10. Ramp 1, Florida -A precast segmental, post-tensioned, balanced cantilever erected by crane with minimal disrup­ viaduct (Designer: Beiswenger Hoch & Associates). tion of traffic on U.S. 90.

38 PCI JOURNAL Four precast segmental box girder grade separation and interchange bridges were completed on the North­ South Tollway near Chicago in 1989. These bridges incorporated both span­ by-span and balanced cantilever erec­ tion techniques. Complex substruc­ tures were required for these bridges, including post-tensioned straddle bents and C bents. A construction view of the Kaneohe Interchange Project on the island of Oahu, , is shown in Fig. 13. The 488 m (1600 ft) main span portion of this interchange was built in bal­ anced cantilever with an overhead gantry used on the adjacent H-3 Wind­ ward Viaduct. The precast segmental Fig. 11 . 1-75/ 1-595 Phase 2 project, Florida (Designer: Beiswenger Hoch & ramp structure was constructed on a Associates). 183 m (600 ft) radius using span-by­ span construction. The variable width precast section shown in Fig. 14 was used to complete the transition between the ramp and the mainline structure. The pier seg­ ments for the mainline structure were cast-in-place with the piers due to seismic considerations. Also, due to seismic requirements, all post-tension­ ing was accomplished with internal tendons (inside segment slabs and webs). This interchange project was completed in September 1994. T he magnitude of the U .S. 183 Viaduct in Austin, Texas (see Fig. 15), incorporating 3332 segments, is be­ yond that envisioned as a primary ap­ plication of the segmental standards. However, at several locations, this project involved span-by-span erection of segments over traffic. Details of the Fig. 12. 1-11 0/ U .S . 90 Bridge, Biloxi, Mississippi (Designer: Figg Eng ineering Group). span-by-span erection are shown in

Vcrle• front 44 • to 53 •

TyptcotCrosa· S.etlon Variable Second Cel

22'· 0" O' to 14' Kaneohe Interchange Romp Transition Two-Cell Box Girder

Fi g. 13. Kaneohe Interchange Bridge, Oahu, Hawaii Fig. 14. Kaneohe Interchange Ramp transition two-cell box (Designer: j. Muller International). girder (precast).

Septem ber-October 1997 39 Figs. 4 and 16. Also, the curved ramps of the interchange between U.S. 183 and I-35 were built in balanced can­ tilever construction, as illustrated in Fig. 17. The last of the 3332 segments in the U.S. 183 Viaduct was placed in November 1996, and the project was completed early in 1997.

PROPOSED SEGMENTAL GRADE SEPARATION AND INTERCHANGE PROJECTS Four ramps of the 1-15/U.S. 95 In- terchange in Las Vegas, Nevada (see Fig. 18), with lengths ranging from Fig. 15. U.S . 183 Viaduct, Austin, Texas (Designer: Texas Department of 490 to 743 m (1607 to 2438 ft), have Transportation). been designed for precast segmental construction with segment details adapted from the AASHTO-PCI-ASBI segmental standards. These bridges in­ 17.7 m corporate seismic connection details between the piers and the precast pier segments. This project is scheduled I for bids in November 1997. LONGITUDINAL The S.R. 9/I-95 Palm Beach Interna­ TRUSS tional Airport Interchange in Florida lt. PROJECT (see Fig. 19) is a four-level fully-di­ rectional interchange that provides ac­ cess to the Palm Beach International Airport. This project includes nine precast segmental bridges totaling 4.7 FRONTAGE ROAD km (2.92 miles) in length. The bridge superstructures are composed of curved precast segmental box girders. Fig. 16. Mainline column, U.S. 183 Viaduct, Austin, Texas, showing Frontage Road, The single-cell boxes will carry one tendons and pier bracket (Designer: Texas Department of Transportation). and two traffic lanes with supereleva­ tions as high as 10 percent. The typi­ cal span is 55 m (180ft), and the typi­ cal segment is 3 m (10 ft) long. The expected bid date for this project is October 1998. The monumental Boston Central Artery Project includes five inter­ changes with precast segmental al­ ternates totaling 105,750 m 2 (1,137,700 sq ft). Bid dates for these projects range from October 1997 to mid 2003. One of the largest and most visible of the Central Artery projects is the 1-93 and Ramps North of the Charles River (see Fig. 20). This ele­ vated bridge structure comprises ap­ proximately 71,570 m2 (770,000 sq ft) of bridge deck. The precast concrete segmental alternate design uses both Fig. 17. U.S. 183 Viaduct, Austin, Texas, view of balanced cantilever construction span-by-span and balanced cantilever (Des igner: Texas Department of Transportation). construction techniques for the erec-

40 PCI JOURNAL steel alternate was $83,603,000. This project has not yet been awarded. • Miami Airport, Dade County, Florida. This project includes 49 bridges. The preliminary design study has recommended that 12 of the bridges with 120770 m2 (1,300,000 sq ft) of deck area be pre­ cast segmental construction utilizing the AASHTO-PCI-ASBI Standard Box Girder Segments. • Ft. Lauderdale Airport, Broward County, Florida. Six bridges ranging from 76 to 457 m (250 to 1500 ft) in length. Fig. 18. 1-15/ U .S. 95 Interchange, Las Vegas, Nevada (Designer: Parsons • Foothills Parkway, Tennessee. Five B ri nckerhoff). grade separation bridges to be con­ structed by the progressive place­ ment method with precast segmental tion of more than 7620 m (25,000 ft) project including areas of double piers. These projects are tentatively of precast segments. decked roadway. scheduled for bid in 1998 and 1999. Typical span lengths range from 30 Other grade separation and inter­ to 61 m (1 00 to 200 ft) and horizontal change projects now being developed curve radii range from 61 to 1980 m include: CONCLUDING REMARKS (200 to 6500 ft). Three distinct super­ • 1-355 South Extension, Illinois. This Completed precast segmental grade structure box girder types will provide project was originally bid on De­ separation and interchange bridges roadway widths from 6.7 to 23.3 m cember 19, 1996, with steel and pre­ have demonstrated significant advan­ (22 to 96 ft). The substructure will cast segmental alternates. The low tages with respect to alternative meth­ consist of three column sizes to sup­ bid for the concrete alternate was ods of construction, which will become port the box girders throughout the $79,122,000, and the low bid for the increasingly important in the next cen-

Fi g. 19. Rendering of the S.R. 9/ 1-95 Palm Beach International Airport Interchange, Florida (Designer: Beiswenger Hoch & Associates).

September-October 1997 41 Fig. 20. Rendering of the 1-93 Viaduct and Ramps north of the Charles River, Boston (Designe r: Figg Engineering Group). tury. These advantages include: segments, and to a lesser extent 2. Muller, Jean, "Ten Years of Experience • Low initial and life-cycle cost through reduction of form costs. It in Precast Segmental Construction," PCI JOURNAL, V . 20, No. I , January­ • Rapid construction seems clear that the widespread avail­ ability of the standard segments at the February 1975, pp. 28-61. • Minimal disruption of traffic 3. Precast Segmental Box local level will be a major determinant • Adaptable to longer spans and Manual, Prestressed Concrete Institute of the success of this new product in curved roadway alignment and Post-Tensioning Institute, Chicago, the marketplace. • Outstanding aesthetics IL, and Phoenix, AZ, 1978. The AASHTO-PCI-ASBI Standard 4. Moreton, Alan J., "Segmental Bridge Construction in Florida - A Review Box Girder Segments will further en­ REFERENCES and Perspective," PCI JOURNAL, V. hance the economy of precast segmen­ I . Kulka, F. , Thoman, S. J., and Lin, T. Y., 34, No.3, May-June 1989, pp. 36-77. tal construction for grade separation "Feasibility of Standard Sections for 5. Muller, Jean M., and McCallister, Linda and interchange bridges through in­ Segmental Prestressed Concrete Box Figg, "Esthetics and Concrete Segmen­ volvement of the industrial base and Girder Bridges," FHWA/RD-82/024, tal Bridges in the United States," Con­ expertise of local precast/prestressed Federal Highway Administration, Wash­ crete International, V. 10, No. 5, May concrete manufacturers in producing ington, D.C., July 1982. 1988, p. 25.

42 PCI JOU RNAL