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14 New Construction Technologies for Rebuilding the Nations Infrastructure C. WILLIAM IBBS AND DIEGO ECHEVERRY The tools and services of the American construction industry are es- sential to the rebuilding and maintaining of this country's infrastructure. Construction engineers focus on the basic building blocks common to many structures: building components, materials, foundations, and the other elements that are combined to create bridges, hospitals, roads, and other infrastructure facilities. In recent years, construction engineering has made substantial tech- nological progress. This progress extends across various subfields of the industry: materials science, materials testing, new construction technol- ogies, robotics, and the application of computers to infrastructure con- struction and management. This chapter presents examples of technological progress in these sub- fields and in the construction industry in general. The examples reflect both the kind of innovative work being carried out and its level of so- phistication. It should be noted that some of the important innovations in the industry are managerial rather than technological. Contractual risk sharing, labor productivity improvement programs, and project financing schemes fall into this category. This discussion, however, will be limited to the "hard" side of construction engineering and management tech- nology. 294

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CONSTRUCTION TECHNOLOGIES 295 THE CURRENT PROBLEM Current concerns about the nation's infrastructure arise from two factors. First, modern life as we know it could not continue without it. Second, there is a growing body of literature that suggests much of the infrastructure in the United States is in a critical stage of decay. Anecdotal and statistical evidence substantiates this claim of decay. Overall, the U.S. Federal Highway Administration estimates that 28 per- cent of the nation's 270,000 bridges are in need of repair or replacement (Constructor, 19861. The Commonwealth of Pennsylvania alone has more than 53,800 highway bridges in use. More than 44 percent of them are 40 years old or more (26 percent are at least 50 years old, and 5 percent are at least 80 years old) (Hoffman, 19861. Older does not necessarily mean worse, but the passage of time has brought problems for many of these bridges. Some 9,400 have been judged structurally deficient or functionally obsolete because of inadequate lane widths, unsafe curve radii, and similar flaws. In Pennsylvania alone the cost of upgrading the bridges to a "desirable status" is projected at $5.7 billion. Sewers, another critical part of the infrastructure, also need overhauling. For example, roughly three-fourths of Boston's sewers were built in the nineteenth century. The system has decayed to the point where some 15 percent of its flow is lost to leaks. New York City water and sewer lines, which may have had design lives of 75 to 100 years, are replaced long after. City engineers there have called for the replacement of 30 percent of all water mains (2,200 miles) within the next 10 years, with costs estimated at $2.45 billion (O'Day and Neumann, 1984~. Choate and Walter (1983), whose book America in Ruins sparked much of the revived interest in public works facilities, estimate that combined government spending from all levels will have to reach $3 trillion in the next decade to maintain the present level of service. A partial list of the most expensive infrastructural items and the estimated cost of their re- furbishing includes: highways and bridges outside urban areas, $1 trillion; city streets, $600 billion; municipal water systems, $125 billion; water pollution controls, $ 100 billion; ports and inland waterways, $40 billion; and prisons and jails, $15 billion. The total amount needed for public works facilities represents an amount roughly equal to planned national defense outlays over the next 10 years. We are committing only about one-third of this needed sum today.

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296 C. WILLIAM IBBS AND DIEGO ECHEVERRY 6 As o Do of - ~4 - o 2 o C) - CL o - - - I I I I 1 1 1 1 1965 1967 1969 1971 1973 Year 1975 1977 1979 1981 1983 FIGURE 14-1 Recent governmental expenditures on the physical infrastructure as a percentage of the gross national product. Source of data: Construction Review, Washington, D. C.: U. S. Department of Commerce. Several factors help to explain this situation. One is the decreasing percentage of public funds spent on government construction (U.S. Bureau of the Census, 1970, 1975, 19861. In less than 20 years, these expenditures have dropped by almost half (see Figure 14-11. Industry inflation compounds this decline in expenditures. As shown in Figure 14-2, annual price increases in the construction industry have ranged up to 20 percent above general economic inflation (U.S. Bureau 400 350 300 US ED O. 250 - ~n CD ._ C - c o - - 200 150 100 50 o Building Cost Index ~ ~ ~/,~ - _' /Consumer Price Index I I I I I I I I 1 1 1965 1967 1969 1971 1979 1973 1975 1977 1981 1983 1985 Year FIGURE 14-2 Inflation in the American construction industry. Source of data: Construction Review, Washington, D.C.: U.S. Department of Commerce.

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CONSTRUCTION TECHNOLOGIES 115 x115 _ a, ~110 _ ._105 _ I> 100 _ O _95 _ o _90 _ _ 11 85 _ a, ~ _80 '_75 3 - ~n o 110 105 100 70 65 60 1947 1952 1957 1962 297 I' it, i, 1967 1972 1977 1982 Year FIGURE 14-3 U.S. construction industry productivity over time. Source of data: Construction Review, Washington, D.C.: U.S. Department of Commerce. of the Census, 1970, 1975, 19869. Thus, governments are not only spend- ing proportionately fewer dollars today, but, taking inflation into account, they are getting less value for their money than they did 20 years ago. Moreover, construction productivity, here interpreted as the value or output generated per unit of input, has been uneven over the past three decades by virtually any measure. For example, the composite labor and capital productivity index has been highly erratic and, recently, about 10 percent below the peak years of 1 96 1- 1 969 (Figures 14-3 and 14-4; Cre- means, 19811. Construction productivity is also low in relation to other components of the national economy (Table 14-1; American Productivity Center, 19841.* Multiple factors explain this decline in productivity: regulations; chang- ing work force demographics; extremely large and complex projects, such as nuclear power plants, that some construction managers were unprepared to handle; and the economic boom of the 1960s all figure into it. Man- agerial complacency coupled with labor militancy may also have been a factor. Regardless of the reasons, the results of the decline have been traumatic and far-reaching. Easiest to understand, perhaps, has been the pronounced shift to more prefabrication and modularization. It is not uncommon, for example, for an entire sewage treatment facility to be assembled offsite and then shipped to its final destination in one piece. Another outgrowth of the cost-productivity trap has been the astonish *For a discussion of issues related to construction productivity and for other sources of information in this area, see National Research Council (1986).

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298 ~- U.S.: ~'-~-'6' 150 to c. ,_ 8 11 00 r ; a) C' a) CL Japan J 5o7 i) 71 72 73 74 75 C. WILLIAlkl IBBS AND DIEGO ECHEVERRY - ~ Germany ~ France ~ - _, - . . \ ~ ~-~ U K 1 1 1 1 1 1 1 1 1 76 77 78 79 Year FIGURE 14-4 Construction productivity of the United States and other selected nations over time. Reprinted with permission from Civil Engineering. TABLE 1 Average Annual Rates of Change (percentage) in Productivity of Labora and Capital,b Selected Sectors, 1948-1983 1948-1983 Sector Labor Capital Business economy 2.3 o. Goods-producing industries 2. g Service-producing industries 1.8 0.2 0.2 Construction 0.4 - 2.3 aLabor productivity = output per hour. bCapital productivity = output per unit of capital. SOURCE: American Productivity Center (1984).

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CONSTRUCTION TECHNOLOGIES In a, ~100 o 3 z 80 C) o 60 3 In O 40 Cat ~20 ID CL o i_ i_ 7////, ~1977 ~1982 299 ///// 1, ~ C, ~ ~ ~1 ,_ _ _, ' FIGURE 14-5 Growth of nonunion construction in the U.S. mechanical trades over time. Reprinted with permission from Civil Engineering. ing growth of the open-shop labor movement. Relaxed work rules and lower wage rates and fringe benefits have cost construction trade unions significant amounts of market share. Figure 14-5 shows the experiences of the mechanical trades, as one example. In total, some 70 percent of U.S. construction today is "merit shop" labor, open without prejudice to union and nonunion workers. Ten years ago, that figure was less than 30 percent. A third major change in the American construction industry recently has been the explosive growth in foreign competition. At one time, Amer- ican builders regularly captured all domestic work and a principal share of the large international projects. Today, as shown in Figure 14-6, that role is being threatened by a number of other nations, depending on the

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300 a) C. WILLIAM IBBS AND DIEGO EClIEVERRY 140 120 100 80 60 40 20 o in ~ ~9d 1982 1983 1984 1985 Year All Others Korea Germany ~3 Britain France Italy Japan United States FIGURE 14-6 International construction market shares of various nations. Source of data: Various issues of Engineering News-Record from 1982 to 1985. market (Pinyan, 1986a). Perhaps even more tellingly, foreign contractors and designers are increasing their stake in this country, which is, for example, the fourth largest foreign market for British contractors. The vast majority of the Japanese automobile plants being built here are de- signed and constructed by Japanese firms. And Swedish and German firms have acquired equity shares in several large American construction firms. Figure 14-7 captures the spirit of this pronounced change (Pinyan, 1986b). In summary, the American construction industry has experienced a severe interruption in economic and technological progress. Yet there are signs that it is reviving. The following sections describe some of the technologies that are making construction more efficient and cost-effective. NEW MATERIALS TECHNOLOGY Over the past several decades, rapid technological change has occurred in various subfields of materials science. Although less visible than the computer technology revolution, these innovations nevertheless have been as pronounced and lasting. Today, the construction industry routinely uses steels twice as strong as those of 15 years ago and concrete mixes three times the standard of 3,000 pounds per square inch (psi) of two decades ago. Other important advances have taken place in corrosive, extreme temperature, and other hostile environment applications. The next section

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CONSTRUCTION TECHNOLOGIES 301 describes several clear cases in which new materials technology has had a positive impact on infrastructure performance and cost-effectiveness. Research in concrete technology has yielded numerous innovations that have been successfully applied in the field. One is the development of superplasticizers, which, when added to concrete, cause dispersion of the cement particles of a concrete brine. This lessens the amount of water required to mix the concrete, and as a result, the hardened concrete is much less porous and consequently much stronger. Superplasticizers have made possible the appearance of commercial brines of 15,000 psi (100 megapascals EMPal); in laboratory conditions, strengths of more than 20,000 psi (140 MPa) have been obtained (Mindess and Young, 19811. These high strengths permit much more cost-effective designs for concrete structures, at an additional cost of 5-10 percent. The inclusion of metallic or polymer fibers in concrete to enhance tensile strength and toughness is another important technological development. Applications have ranged from using fibers as overlays in pavements, to the solid construction of blast-resistant structures (Mindess and Young, 1981~. Many other recent developments in concrete technology can lower 8000 7000 6000 5000 a - ~3000 4000 2000 1000 o _ 1--:-:::1 : :.:.:: :l Japan 1 1 _ ~ _ All Others France Britain Germany ~ <,,,,v ;~ 1 i 1' 1980 1981 1982 1983 1984 1985 Year F~GuRE 14-7 Foreign contractor shares of the U.S. market over time. Source of data: Various issues of Engineering News-Record from 1981 to 1986.

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302 C. WILLIAM IBBS AND DIECO ECHEVERRY costs and heighten the effectiveness of infrastructure facilities. (Polymer- impregnated concrete and the use of cement-replacing admixtures and accelerants are two examples.) One of the most interesting and simplest recent material technology innovations has been the concept of roller-compacted concrete (RCC). This material is a combination of Portland cement and selected on-site clays and silts mixed together to form a low-strength composite. The most noteworthy application of RCC has been at Willow Creek Dam in Oregon, a facility designed and owned by the U.S. Army Corps of Engineers. The success of this project can be measured in several ways, all of which are related to the new material. The construction time was 1 year (a rockfill dam would have required 3 years); it cost about $10 million less than the second cheapest method explored; and the cost of concrete per cubic yard was one-third the cost of traditional concrete. These results were obtained by combining novel ideas with known tech- niques. Figure 14-8 shows the construction methods used in putting this innovative material in place. RCC has two important advantages over traditional concrete: (1) lower cement content and (2) reduced handling and placing costs. When fresh, RCC resembles a silty gravel and thus can be spread and compacted with earthmoving equipment. The labor costs associated with this procedure are much lower than those typical of labor-intensive systems of handling and placing concrete. The successful implementation of these innovative ideas is due in part to good management practice. Work on the Willow Creek Dam had to start in the early spring; all of the RCC had to be in place by late fall. The initial program planned 122 days for placing the concrete, and it was actually performed in 124 days. In spite of the new techniques used and the crews' inexperience with this type of project, the work was finished on schedule and with a relatively low cost overrun of 12 percent (Schrader, 1982; Civil Engineering, 19851. The practical benefits of better materials are also visible in the tech- nology of metals, particularly corrosion protection. Metals, especially steel, are present in reinforced concrete structures, underground pipelines, bridges, storage tanks, and many other structures. New corrosion-resistant alloys, as well as enhanced corrosion protection methods, should signif- icantly reduce maintenance and repair costs of these facilities. NEW MONITORING AND SENSING TECHNOLOGIES As in other fields, computerization and miniaturization have profoundly affected monitoring and construction equipment. Improvements have been

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303 .N ~5 ~As-= 0 1 ~ CO 1:5 Ash 3 as ~ s a' Cal o o U - 3 .= ~ ~ As, ~ LLI ~ _ C' rr n' AN tt;-i 1 Q S g 0 O C (D O E ~ ~ o ~E c o ._ U. .= E o ~5 .O a. U. Cal o so o ._ 4 - o C) _' au o C) Cal o 1 - o so q) o s:: o ._ C~ C~ s~ C) ._ . Ct c; C) ~ . _ oo ~ 1 ~ ;> ._ v o

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304 C. WILLIAII7I IBBS AND DIEGO ECHEVERRY made in earthmoving operations, for example, by adapting sensors to bulldozers and scrapers to improve placement tolerances and operators' fields of vision. Electronics systems now conduct actual real-time, non- destructive testing by acoustical and x-ray diffraction means. And longer wearing, more heat-resistant brake pads have permitted the development of haul trucks with a capacity of 150 tons, something unimaginable only a few years ago. Computerized monitoring is improving safety and efficiency during and after construction. For example, Florida's Sunshine Skyway Bridge is now being replaced with one of the longest cable-stayed bridges in the world, with a main span of 1,200 feet (ft). Embedded within the concrete segments of the bridge deck and bridge piers are strain meters and tem- perature sensors. With the assistance of a microcomputer-based system, these instruments monitor various deflections and deformations of the structure during and after construction. The Florida Department of Trans- portation can thus assess the structural condition of the bridge and ac- curately record its performance over its service life (DiVietro, 19861. A similar computerized monitoring of a nuclear containment structure is described by Pinjarkar (19821. Energy-efficient, safer, better organized buildings are operated with computers and control systems that monitor and adjust temperature, the degree of illumination of public areas, ventilation, and other variables. The tools to automate water and wastewater systems are also available today in a technology that consists of automated control devices linked through microwaves with a computerized control device (Bishop and Schuck, 1986~. NONDESTRUCTIVE TESTING Nondestructive testing techniques promote increased confidence in the quality of built components. At the same time, they reduce the cost of inspection and testing. Most of these techniques are used on concrete structures and pavements, although some are also applied to underground . pipe. fines. One important class of devices used for nondestructive testing employs different types of electromagnetic or ultrasonic waves. One such technique is the ultrasonic pulse velocity method for measuring the strength of concrete. Others are the radar and x-ray devices that locate and identify reinforcing bars inside a concrete element. Employing a similar principle, ground-penetrating radar is used to locate underground objects. In some areas, optical devices are moved to inaccessible places for the visual

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COlVSTRUCTIOlV TECHNOLOGIES 305 inspection of facilities. (For example, television cameras are used to eval- uate the internal condition of sewer systems.) Another type of device applies a known force at the surface of the material with a special hammer and measures the resulting deformation to infer the strength of hardened concrete. A variety of devices, all based on this approach, are used to determine the properties of pavement. NEW CONSTRUCTION METHODS Improved construction methods are having important effects on the initial costs of facilities, the speed of their completion, and the quality of service provided to users. An important area of potential savings in time and money is the construction, repair, and reconstruction of pavement. The savings are proportional to the size of the existing investment and the volume of annual spending in this area-an estimated $10 billion (Forsyth, 19851. A number of new methods are currently being used. For instance, the development of filter fabrics for pavement drainage and different types of synthetic fabrics for crack control have helped to reduce costs and extend the useful life of many pavements. New or improved equipment that produces higher quality pavement at lower costs includes electronically controlled slipform pavers and new pavement breakers (Ray, 19861. Pavement recycling technology is another recent innovation for cutting reconstruction costs. This method uses the old pavement as a raw material for new pavement. At the same time, pavement maintenance costs may be reduced by the construction of so-called zero-maintenance pavements. In combination with subgrade and enhanced drainage, pave- ments can provide virtually maintenance-free service for their first 20 years (Saxena, 19821. Bridge construction and repair are also top candidates for improvements and savings through innovative construction techniques. The repair of the Zilwaukee Bridge, currently in progress in Michigan, clearly demonstrates the kind of savings that are possible. During its initial construction in 1982, this bridge suffered huge displacements in essential parts of its structure, largely because of foundation shifts. In the past the only recourse would have been to demolish and rebuild the bridge. Instead, using new construction techniques, the engineers repaired the affected pier and col- umns and saved some 6,000 tons of high-strength concrete. During the repair work the ground that supported the damaged pier was frozen to increase soil resistance while construction crews built additional support. Hydraulic rams were used to restore the columns to a vertical position (Arnold, 1986). New techniques for tunneling and pipeline construction are also prom

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306 C. WILLIS IBBS kD DIECO ECHEVERRY ising to improve the infrastructure. One example is the successful use of hydraulic jacks to force hollow concrete units into the ground. This method minimizes the disturbance of surface activities and is economically com- petitive with open-cut construction (Phillips, 19841. Successful prelimi- nary experiences have also been reported using robotics for tunnel construction; robots can carry out faster and more precise tunneling (Shi- momura and Sonoda, 19841. CONSTRUCTION ROBOTICS Indeed, the promise of construction robotics is becoming a reality as advances in machine vision, mobility, and navigability lead to prototypes. Developers must proceed carefully, however, because construction robots are much more complex instruments than factory robots. A construction robot moves to a work task; a factory robot is stationary, and the work moves to accommodate the assembler. Moreover, construction robots face a range of loads, changing terrains and dynamic environs, and a highly variable weather environment. Nevertheless, robotics research has been spurred by the promise of better quality control, productivity, health and safety, and cost-effective- ness. Today, modest research programs in construction robotics are in place at Carnegie Mellon University, the University of Illinois, M.I.T., and other institutions. The recent application of construction robotics in- cludes the tethered robot that assisted in the cleanup of the damaged Three- Mile Island reactor. REX, a robot designed at Carnegie Mellon University, has proved useful for excavation near leaking gas utility lines. Most of the pioneering research and development in construction ro- botics is taking place in Japan. The Japanese have tested a variety of applications, including prototypes for exterior building wall tile inspection, concrete floor slab placement and finishing, three-dimensional structural steel erection, and abrasive water jetting for tunneling. The most advanced Japanese robotic experiment involves a fireproofing system (Yoshida et al., 19841. The SSR-2 robot used in the system consists of four key components: a base, vertical and horizontal arms, and a wrist (see Figure 14-91. This manipulator has six degrees of freedom and is driven by a playback-control system consisting of light friction-type cyl- inders; a potentiometer at the end of the arm senses the position of the arm relative to the steelwork to be fireproofed. Both the SSR-2 and its predecessor, the SSR-1, must be "trained," in the sense of being led through the first of many similar passes. A small 16-bit computer control and power system is tethered to the mobile unit. The dimensions of the

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CONSTRUCTION TECHNOLOGIES I, Power unit Controller Distance sensor 307 Fireproofing material Position sensor SPRAY WORK (Potentiometer) Spray manipulator ~ , Spray nozzle Beam or girder \\~.JT 1l ~ Variable length (500mm) ,~3 1 Traveler (Revolutlon+90) il5~5~ (Rotary encoder) -.-' ~ _ ~ Stirrer- Blower | PLANT l -Outrigger ~ Rock wool /Rock woo) ~ / Water it'' ~; flint Vlbrator J ,~ ao O Reck wool feeder Cement milk pump I Cement milk t 1 FIGURE 14-9 Japanese fireproofing robot. Reprinted with permission of Skimizu Construction Co., Tokyo.

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308 C. WILLIAlkl IBBS AND DIEGO ECHEVERRY unit are approximately 2 meters (m) by 3 m with a vertical reach of 3 m. The unit weighs about 800 kilograms. The true test of the viability of this robotic sprayer is whether it costs less than conventional methods. Only limited full-scale testing has been completed thus far. But in one experiment involving a 20-story office building, 100 units of various sizes and lengths were coated by the machine and an equal number by human crews. The robot took a total of 62 hours (h) to set up, transport, spray, and finish; the human team took 112 h. Moreover, the quality of the final product was substantially better when the fireproofing was placed mechanically. Today, robotic and other intelligent machines are finding new appli- cations at a steady pace. A part of this application pattern can be ascribed to the considerable research and development investment that has already been made; part is also attributable to the slowdown in worldwide con- struction activity. Nevertheless, it is predictable that robotic construction will soon have a place alongside more traditional building activity. NEW MANAGEMENT TECHNOLOGIES Another set of technological innovations is developing in the field of construction management control. Traditionally, management information systems have been good vehicles for reporting data but have been deficient in reporting information and providing control. Several new approaches, however, may replace the old systems. Two advances involve sophisticated applications of mathematical simulation. The first advance grew out of work by Paulson at Stanford University. It is the actual modeling and "what if" analysis of construction field op- erations that is, the flows and balances of equipment, labor, and material on large projects. An interactive, graphical tool, Paulson's INSIGHT system is becoming more accepted and valued (Ibbs, 19851. The second, a simulation model, AROUSAL, deals with the project management as- pects of construction (Ibbs, 19851. AROUSAL is the brainchild of Lan- dsley at the University of Reading (U.K.~. It models such decisions as personnel staff assignments, hiring, and skill training. Several firms in the United Kingdom and the United States are using this system. The greatest advances in management control technology promise to be in another computer-aided construction field: the relatively new science of artificial intelligence. Knowledge-based expert systems (KBES) in par- ticular are being seized on by researchers and practitioners alike almost as panaceas. Today, KBESs exist for project risk assessment, evaluation of a contractor's safety program, and project goal setting. One specific application of KBES technology that attempts to solve a

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CONSTRUCTION TECHNOLOGIES 309 long-standing problem is being carried out at the University of Illinois. Ever since builders and managers began to represent project flows math- ematically, they have faced problems analyzing construction schedules for adequacy and completeness. Project owners need summary schedules to forecast completion, phased occupancy dates, and cash flow require- ments and to prepare and defend against contractor claims for extra costs. CONSAES, a construction schedule analysis expert system under devel- opment at the University of Illinois and the University of California, Berkeley, is a serious attempt to provide the U.S. Army Corps of Engi- neers with such a management tool. The system checks schedules initially and during the project and updates them in terms of cost, time, and constraints inherent in the logic of construction tasks. For example, the cost module analyzes cost-weighted schedule activities to ensure that un- reasonable "front-end loading" is not present. CONSAES is now being tested at a number of Corps locations world- wide. Continual updates are being made, and a study is in progress to assess the payoff of the investment. The consensus is that this tool and its underlying technology are so valuable to construction management that many other applications will soon be tested. DATA BASES FOR MANAGEMENT Data bases, automated data-collection devices, and their linkage and support systems are also contributing to better management in ways that help keep construction and repairs to a minimum. If a computerized in- ventory of infrastructure facilities contains information on operating char- acteristics, maintenance and repair needs, and other data, it can provide excellent assistance when budgeting and setting priorities for resource allocation. The same inventory can be used to support a computerized system for scheduling maintenance and repair activities. In several juris- dictions, data bases are already being used for these purposes. The state of Washington has been a pioneer in computerizing the in- ventory of infrastructure facilities. In 1978 Bellevue, a suburb of Seattle, developed a fully operational data base of its water supply system. By 1984, an automated mapping system was installed and running, designed to manage information on the lot sizes and topography of Bellevue. Today, several other data bases, such as those for building permits and the as- sociated property improvement activity, are being developed or are in use. At the same time, the city is developing software to integrate all the data bases to facilitate data sharing among systems. A maintenance operations and management system is also being designed to improve the efficiency of the maintenance departments. This effort has already resulted in better

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310 C. WILLIAM IBBS AND DIEGO ECHEVERRY planning and management of the infrastructure of Bellevue (Godfrey, 1985~. In another example, the Pennsylvania Department of Transportation set up a bridge management system in 1986 to manage data from more than 50,000 bridges larger than 8 ft. The system is designed to keep updated records of the facilities, recommend bridge maintenance and repairs, and estimate costs. Although not especially sophisticated, this system will put bridge maintenance and repair on a more rational basis and should make it easier to set priorities and plan budgets (Hoffman, 19861. In summary, new materials and innovative technologies will play sig- nificant roles in our attempts to rebuild and maintain the nation's infra- structure. Today, these technologies are being used to create maintenance- free pavements and metal bridges more resistant to corrosion. At the same time, construction technologies are making it possible to build elements of the infrastructure more efficiently, safely, and cost-effectively. Tech- nology is also improving management through such tools as computerized project planning systems and data base management methods. In all of these areas, the technology is still developing and will continue to develop. Meanwhile, solutions to the immense problems posed by our deteriorated national infrastructure will demand every new technology that construction researchers can devise and that practitioners can implement. ACKNOWLEDGMENT This material was based on work supported by the National Science Foundation under grant no. MSM-84-51561, Presidential Young Inves- tigator's Award. Any opinions, findings, conclusions, or recommenda- tions expressed are those of the author and do not necessarily reflect the views of the sponsors. REFERENCES American Productivity Center. 1984. Productivity and the U.S. Economy. Houston, Tex.: American Productivity Center. Arnold, C. J. 1986. Salvaging the Zilwaukee. Civil Engineering 56(4):46-49. Bishop, D. F., and W. Schuck. 1986. Water and wastewater: Time to automate? Civil Engineering 56(1):46-48. Choate, P., and S. Walter. 1983. America in Ruins: The Decaying Infrastructure, M. Barker, ed. Washington, D.C.: Council of State Planning Agencies. Civil Engineering. 1985. Dam pioneers concrete variant. (July):42-45. Constructor. 1986. Washington, D.C.: Associated General Contractors of America. No- vember. Cremeans, J. E. 1981. Productivity in the construction industry. Construction Review 27 (May-June):4-60

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CONSTRUCTION TECHNOLOGIES 311 DiVietro, P. 1986. Monitoring a bridge's pulse. Civil Engineering 56(3):54-55. Forsyth, R. A. 1985. Recent developments, future needs and opportunities in pavement technology and management. P. 39 in Proceedings of the Conference on Infrastructure for Urban Growth. New York: American Society of Civil Engineers. Godfrey, K. A., Jr. 1985. Data base in your city's future. Civil Engineering 55(10): 66-69. Hoffman, G. L. 1986. Bridge management: Computer aided priorities. Civil Engineering (May):62-64. Ibbs, C. W. 1985. Proceedings of a Workshop for the Development of New Research Directions in Computerized Applications to Construction Engineering and Management Studies. Construction Research Series Technical Report No. 19. University of Illinois. Mindess, S., and J. F. Young. 1981. Concrete. Englewood Cliffs, N.J.: Prentice-Hall. National Research Council. 1986. Construction Productivity: Proposed Actions by the Federal Government to Promote Increased Efficiency in Construction. Washington, D.C.: National Academy Press. O'Day, K., and L. A. Neumann. 1984. Assessing infrastructure needs: The state of the art. Pp. 67-109 in Perspectives on Urban Infrastructure, R. Hanson, ed. Washington, D.C.: National Academy Press. Phillips, S. H. E. 1984. Tunnel and bridge construction with minimum disturbance to overhead service. Pp. 172-183 in Proceedings of the Conference on Rebuilding America: Infrastructure Rehabilitation. New York: Metropolitan Association of Urban Designers and Environmental Planners. Pinjarkar, S. G. 1982. Data acquisition and process control. Journal of the Technical Councils of ASCE 108(May):89-95. Pinyan, C. T. 1986a. Foreign contracts inch upward. Engineering News-Record 217(3): 38-42. Pinyan, C. T. 1986b. Foreign contracts inch upward. Engineering News-Record 217(22): 12-13. Ray, G. K. 1986. Progress in paving equipment and construction methods. Concrete Construction 31 (5):439-445. Saxena, S. K. 1982. New structural systems for zero-maintenance pavements. Transpor- tation Engineering Journal 108(TE2): 169- 182. Schrader, E. K. 1982. The first concrete gravity dam designed and built for roller compacted construction methods. ACI Concrete International (October):169-182. Shimomura, Y., and T. Sonoda. 1984. Tunneling by robots-Shield driving automatic control system. Proceedings of the Workshop on Robotics in Construction. Carnegie Mellon University. U.S. Bureau of the Census. 1970, 1975, and 1986. Statistical Abstract of the United States. Washington, D. C.: U. S . Department of Commerce. Yoshida, T., T. Veno, M. Nonaka, and S. Yamazaki. 1984. Development of spray robot for fireproof cover work. Proceedings of the Conference on Robotics in Construction. Carnegie Mellon University.