The world's busiest land port crossing, at San Ysidro, Calif., reopened its 24 northbound travel lanes from Mexico on Sept. 18, five days after a 50-ft by 50-ft temporary wood platform, meant to catch demolition waste on a $577-million border station renovation, collapsed and rained heavy debris on vehicles and personnel. One construction worker was seriously injured, and 16 other people also were hurt, including three laborers. Concrete, metal supports, wooden planks and a large black tarpaulin damaged 15 vehicles. Rescuers extracted three people from the wreckage.Miller Environmental Inc., Anaheim, Calif., was removing plaster from an administration building set for
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.