词条 | viaduct |
释义 | viaduct bridge ![]() The long spans of Roman viaducts were supported by semicircular arches resting on piers of stone or masonry. A well-preserved example is the span over the Tagus River at Alcantara, Spain (c. AD 105). The next advance in viaduct construction did not occur until the late 18th-century development of iron bridges and the 19th-century introduction of steel. In the early 20th century the spread of reinforced-concrete construction led to the building of concrete arch structures such as the Colorado Street viaduct over the Pasadena Freeway in California (1938). A recent method used on long viaducts is segmental construction. The sections are precast and jacked forward from one end of the viaduct to form the extension. |
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