Bridges (For Notable Civil Engineering Projects, see Table.) Repairs, renovations, and rehabilitations gained prominence in 1997 as bridges throughout the world revealed the need to be strengthened for 21st-century traffic loads and to be upgraded to meet new earthquake-resistant design standards. In regard to the latter, five crossings of the bay area around San Francisco required major upgrades. Some work was under way on the approaches to the Golden Gate Bridge, though funding was still required for the main towers, the main span, and the Fort Point arch. Design and initial construction upgrading work was also under way on the Richmond-San Rafael Bridge, which needed huge new foundations and strengthened steel work. Most problematic was the San Francisco-Oakland Bay Bridge, which needed about $1.5 billion worth of work. The suspension section was to be upgraded to withstand seismic shocks better, but costs for upgrading the viaduct were so high that a $1 billion replacement was to be built. A variety of designs were proposed, including exotic tilting cable-stays and a single-pylon suspension span, though none would be built until after 2000. On a positive note, 1997 witnessed the resurgence of the suspension bridge, the most suitable design for the longest spans. In Hong Kong the outgoing British administration celebrated the opening in April of the 1,377-m-long central span of the Tsing Ma suspension bridge with fireworks and a speech from Baroness Thatcher (1 m = 3.28 ft). Though second in length to Britain's 1,410-m Humber Bridge, Tsing Ma was the sturdiest of the long suspension bridges, carrying not just a dual three-lane highway to the airport but also a high-speed railway inside its steel deck box. The bridge also had to withstand typhoon-force winds. Humber's length record would not last much longer. During the year the last deck sections were lifted into place for the 1,624-m central span Great Belt (Store Blt) East Bridge in Denmark, part of an extended crossing between the islands of Zealand and Funen. The bridge carried a dual two-lane highway. When completed in 1998, Great Belt East would not hold the world length record for long. In Japan the 1,991-m-long Akashi Kaikyo suspension bridge was nearing the end of its 10-year construction program; it would form the major element of a second crossing to Shikoku Island from Honshu, Japan's main island. China was pressing ahead with plans for a 28-km (17.4-mi) crossing of the Pearl River Delta to Hong Kong, mainly on a viaduct though including a 1,400-m span, a 900-m span, and a 250-m span. In Bangladesh the 9-km (5.6-mi) Bangabandhu Bridge (until August 28 the Jamuna Multipurpose Bridge) was taking shape; it would cross treacherous and deep soft silts and a riverbed that shifted alignment every year. Huge steel piles up to 100 m long and 7 m in diameter supported the piers for the 99-m-long precast concrete deck spans that were being placed one every 12 days. Finally, a small cable-stayed bridge completed during the year in Kolding, Den., may have been a portent of the future. Just 40 m long, it could support a five-ton tractor load easily, but the deck weighed only two tons because it was made of reinforced polyester. A normal concrete deck would weigh 30 tons. According to some industry observers, plastic and carbon-fibre bridges might eventually exceed those of steel by a factor of two in length.ADRIAN LEE GREEMAN This article updates bridge. BUILDINGS (For Notable Civil Engineering Projects, see Table.) Architects had long dreamed that exterior walls of buildings would protect yet breathe--like human skin. That dream came one step closer to reality in 1997 with the completion of two office towers. The "skin" of the headquarters for RWE AG in Essen, Ger. (Ingenhoven, Overdiek, Kahlen & Partners, architect, Dsseldorf), consisted of two layers sandwiching a 50-cm-wide air space (1 cm = 0.39 in). The outer layer of glass incorporated ventilating slots; an inner glass layer slid open as needed. With the outer ventilating slots closed, the air space acted as an insulating layer. When the slots were open, the air space became a cooling chimney; hot, stale air rose and was exhausted, and cooler fresh air was drawn in. The extensive glass usually eliminated the need for daytime electric lights (automated blinds set between the glass layers offered protection from solar heat and glare). The building's exposed concrete slab absorbed heat generated during the day, reradiating it at night for winter heating or summer precooling. These design elements reduced RWE's energy use to well below Germany's strict requirements. At the same time, users had a great deal of discretion in the control of temperature, ventilation, and light. While many of the same techniques were used by the London-based firm of Sir Norman Foster & Partners in the design of the Commerzbank tower, completed in Frankfurt, Ger., that project took natural ventilation one step farther. Excess heat rose within the full-height open internal shaft, and fresh air was drawn inward through four-story gardens carved into the exterior. Another benefit was that inside offices, which could legally be windowless in some countries but not in Germany, opened onto the gardens. The Getty Center in Los Angeles opened in December after 14 years of design and construction. At 87,790 sq m (945,000 sq ft), it was among the largest cultural complexes ever constructed at one time. Among its innovations was a louver and skylight system that precisely limited the amount of natural light falling on sensitive paintings. Several large Asian airports were under construction during the year. The first 516,000-sq m (5,554,000-sq ft) terminal area at Chek Lap Kok airport in Hong Kong (Sir Norman Foster & Partners, architect; Ove Arup & Partners, engineer) was roofed in huge 36 36-m vaults supported by a steel lattice set at a diagonal (36 m = 118 ft). Seoul, S.Kor.'s vast international airport was divided into a "land side" of ticketing, baggage, and ground-transportation functions linked by an underground automated people mover to several linear "air-side" terminals for boarding and deplaning (Fentress Bradburn, Denver, Colo., with the Korean Architects Collaborative International). Kisho Kurokawa (Japan) designed satellite terminals for Kuala Lumpur, Malaysia's airport that evoked the tropical environment, using tree-form column-trunks that supported inverted double-curved roofs ("branches"). Highly sophisticated computer-modeling software enabled the design of buildings of unprecedented sculptural complexity. Chief among them was the Guggenheim Museum that opened in Bilbao, Spain. CATIA, the computer software used by architect Frank O. Gehry (Santa Monica, Calif.) not only helped realize the museum's sinuous titanium-clad vaults and flowerlike forms; it also analyzed the supporting steel structure, conveying to the fabricator the loads and geometries of the connections and thereby greatly reducing the time needed to calculate their proper strength. JAMES S. RUSSELL Dams (For Notable Civil Engineering Projects, see Table.) More than 1,500 dams were reported to be under construction throughout the world in 1997. The largest numbers were being built in India (650), China (280), Turkey (173), South Korea (131), Japan (126), Iran (49), and Brazil (42). There were 175 dams completed in 1996. The number of new dams on which construction had begun during the past few years varied between 200 and 300. This annual addition of dams was expected ultimately to move upward as population growth stimulated increases in food production, the need for additional municipal water supply and sanitation, and production of hydroelectric power. Still, dams continued to be a subject of controversy, as some claimed they did more harm than good. Organizations were formed to support both sides. Some called for referees, committees, commissions, and governmental bodies to express the wisdom that should prevail, to identify what was fair, and to discern between right and wrong. Dam safety continued to command the attention of dam owners and designers. Engineers continued to meet under the auspices of the International Commission on Large Dams, an organization that exchanged views on new developments and experiences and presented technical case studies. Alertness to natural threats was also constantly required. In Nepal, for instance, the Khimti Dam and hydroelectric plant faced the threat of being swept away by the possible failure of a frozen mass of glacial moraine that was holding back 80 million cu m (2.8 trillion cu ft) of water in a lake. Emergency measures were instituted to prevent a disaster. As dams age, modifications to enhance their safety become important design and construction activities. At the beginning of the year, 40 dams were under construction in the U.S. The highest (168 m [1 m = 3.28 ft]), Seven Oaks Dam in California, was designed to be a flood-control project. The Eastside Reservoir Dam, also in California, was being built as a very large water-supply project and would consist of three dams--of 87 m, 56 m, and 40 m in height. In China the first phase of the Three Gorges Dam on the Chang Jiang (Yangtze River) was scheduled to be completed in 1997. Diversion of the river from its main channel began in November.(See Sidebar.) In Laos the environmental assessment of the Nam Theun 2 Dam was being reviewed. Opponents claimed that the dam would drown 470 sq km (180 sq mi) of remarkable grasslands and forests on the Nakai Plateau, several rare animal species would disappear, and the fisheries that helped feed thousands of people would be wiped out. Supporters, on the other hand, claimed that Nam Theun 2 would help lift Laos from the bottom rung of the poorest nations. In Vietnam the centrepiece of the nation's hydroelectric program was the 3,600-MW Son La Dam (at a cost of $3.5 billion), scheduled to be finished by 2007. An active dam program in Iran was aided by available foreign money funding. The 1997-98 program called for the completion of six dams already under way and for the start of seven more in 1998. Turkey announced a program to start 19 dams with a combined capacity of 1,534 MW. Work was continuing on the 510-MW, 210-m-high concrete-arch Berke Dam on the Ceyhan River. The biggest project under way in Syria was the Martyr Basil al-Assad storage dam. The 45-m-high dam, with a 4.5-km (2.8-mi) crest length, was being designed to store 600 million cu m (21 trillion cu ft) of water and allow 55,000 ha (135,850 ac) to be irrigated. T.W. MERMEL This article updates dam. Roads (For Notable Civil Engineering Projects, see Table.) In 1997 the world's first all-electronic toll highway opened in Toronto. Highway 407 was to be a 69-km-long (1 km = 0.62 mi) route running east to west around the north of the city, to ease congestion on the existing main artery, Highway 401. The first 36-km section, built at a cost of about $900 million, was opened to traffic in June but initially without its advanced toll-collection system. Under this system, those wishing to use the highway would be required to have a windshield-mounted transponder that would record their journeys and make an automatic charge for the appropriate toll. Vehicles without a transponder would be recorded through an automatic license-plate-recognition system. Drivers could travel at highway speeds, and control gates would not be required. Difficulties in commissioning the technology led to a series of delays, during which time drivers were allowed free use of the highway. This made the problem worse, as traffic volumes grew rapidly beyond the forecast figures. The installation of additional toll-recording and video-recognition devices finally allowed the technology to be switched on in October, almost a year late. Many highway developers were watching developments on 407 with great interest. When the technology could be demonstrated to be effective, it would make the construction of new toll roads almost anywhere in the world more attractive to financiers. Because the system did not require large areas of land for a traditional toll-collection plaza, it would also allow existing non-tolled highways to be converted to toll routes with comparative ease. Throughout the world the movement toward financing road infrastructure by means of private sources and tolls continued to gain popularity, but in one country it went backward. In the late 1980s Mexico had embarked on one of the world's biggest road-building programs, which envisioned the construction of 6,000 km of new high-quality highways. The highways would be built by private companies that would be allowed to operate them and charge tolls for a concession period before ownership reverted to the government (a system known as build-operate-transfer). Economic difficulties and the devaluation of the Mexican peso in 1994-95 resulted in insufficient revenue for servicing the debts. The government was forced to buy back some of the toll roads and assume $5 billion worth of debt. An alternative system to encourage private-sector financing of highways also was inaugurated in 1997. A bypass around the town of Haltwhistle in northern England was the first "design-build-finance-operate" project to be completed. A private developer built the highway and was to be repaid by the government on the basis of the number of vehicles using the highway, although the drivers themselves would not be required to pay--a system known as "shadow tolling." A major international conference in October discussed plans to revive the Silk Road, an ancient trading route linking Europe and China. The latter was thought likely to become the largest single market for highway development and was beginning to welcome private-sector investment for its ambitious construction projects. RUSS SWAN This article updates road. Tunnels (For Notable Civil Engineering Projects, see Table.) One of the most shattering events of 1997 occurred in a highway tunnel in Paris when Diana, princess of Wales--along with two of three companions--died following a car crash on August 31. (See OBITUARIES.) The car, traveling at a high speed, went out of control and hit a central concrete pillar supporting the roof of the 142-m (465-ft)-long highway underpass built in 1954. Despite steep dips into the tunnel with relatively tight curves close to the portals, there were no crash barriers on either side of the roadway. There were two other significant accidents in tunnels during the year. In September high concentrations of acrylamide and methylolacrylamide in a chemical grout being used to control heavy water ingress during drill-and-blast excavation of the 8.6-km-long Hallandss railway tunnel in Sweden (1 km = 0.62 mi) drained into a local stream and poisoned a herd of cows. The neurotoxic acrylamide was suspected of having been washed out before the two liquid solutions of the grout had time to polymerize to form the impermeable and inert rubberlike grouting material. An immediate investigation suspended tunneling and initiated an intense testing program of the groundwater wells from which the local rural community drew its drinking water. In July a subway tunnel collapse in So Paulo, Braz., took with it a private home. There were no fatalities or serious injuries, but several residents had to be evacuated. All, however, was not tragedy and misfortune. London design started on the 26 km of twin-tube soft-ground tunneling on the new 108-km high-speed rail link to the British terminal of the Channel Tunnel. The estimated 3 billion project was scheduled to open in 2003. In Germany work progressed on the 177-km Frankfurt-Cologne high-speed railway, which was to include 27 single-tube, double-track tunnels totaling some 40 km. In Italy excavation of 23 tunnels to house 30 km of the 220-km Rome-Naples high-speed rail line continued, and work started on the 90-km Florence-Bologna line, 71 km of which was to be in a series of tunnels. In India the last 40 m (130 ft) of difficult soft-ground tunneling marked the successful completion of the 760-km Konkan railway between Bombay (Mumbai) and Mangalore. Some 83 km of the line extended through 92 tunnels along the rugged west coast of the subcontinent, where viaducts across the valleys linked tunnels through the hills. During the year China received two 8.8-m (28.9-ft)-diameter Wirth TBMs (tunnel boring machines) and their entire support systems from Germany for the 18.5-km Qinling railway tunnel in Shaanxi province. The TBMs were to excavate the east tube of the twin-tube double-track railway tunnel, working toward a mid-tunnel junction, whereas the parallel west tube was to be excavated by a drill-and-blast method. One of the most significant water-associated tunnels begun in 1997 was the 29-km-long first of the four tunnels on the 70-km Inland Feeder project in southern California. The project would deliver nearly 2.5 billion litres (650 million gal) of water per day from the Colorado River and California State Water Project aqueducts into the new Eastside Reservoir. The new reservoir would secure a six-month emergency storage of drinkable water for Los Angeles should a major earthquake sever the city's vital water-import aqueducts. SHANI WALLIS This article updates tunnel.
YEAR IN REVIEW 1998: ARCHITECTURE
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