Sama mees leiutas ka pingebetooni. 11. Rippsildade areng (kuulsamad ja nende üldiseloomustused) Esimene ehitati Euroopasse 1741 üle Teesi jõe 21m avaga jalakäijate sild. Tee rippus kettide küljes. 19 saj saadi aru, et rippsild on odavaim, saleda konstruktsiooniga, lihtne ehitada, kuid seda teatud piirini, sest liiga pikad avadetailid olid ebastabiilsed. Märgilise tähendusega oli George Washingtoni sild Hudsoni jõel 1931.a. rippuva ava pikkus 1067m. , mis algatas rippsildade ehitamise laine. Golden Gate San Francisco 1937.a. L-1280m Verrazano New York 1964.a. L-1300m Maailma pikim Akashi-Kaikyo 1998.a. L-1991m, üldpikkus 3,9 km 1998 Pikim meresild Läänemeres Malmöt ja Kopenhagenit ühendav vantsild 7845m 12. Tunneliehituse areng kanalid, raudteetunnelid, Alpi tunnelid kuidas on toimunud areng. Mis on eriti hoogustanud ja millal tunneliehitust. Kõige märkimisväärsemad tunnelid
railways. Examples in Europe include the Viaduc de Barentine (1846), constructed by British navvies under the direction of MacKenzie and Thomas Brassey in brick rather than stone, and the Viaduc de Saint-Chamas (1847), both in France. In the United Kingdom, notable viaducts include the 181ft (55m) Ballochmyle Viaduct (1848), designed by John Miller for the Glasgow & South Western Railway, the largest masonry-arch span in the country; the Harrington Viaduct (1876), the longest at 3500ft (1067m), carried on 82 brick arches; the Meldon Viaduct (1874), the best surviving iron viaduct in Devon; and, in concrete, the Glenfinnian Viaduct (1898), which has 21 arches of mass-poured concrete. Most notable of the early trestles was the Portage Viaduct in the USA (1852), a remarkable timber structure designed by Silas Seymour, carrying the Erie Railroad over the Genessee River, 234ft (71m) above the water and 876ft (276m) long (Figure 14). It was destroyed by fire in 1875, to be
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