Managers of London’s Crossrail railroad have chosen the final five of 24 design teams for the estimated $26-billion project, said to be Europe’s largest infrastructure job. Last month, Crossrail Ltd., short-listed five international consortiums to compete for the two main tunnel contracts, extending 18.1 km, with awards due by June. Preparatory work on the tunnels’ western portals, at Royal Oak, is due to start this month. The 118-km east-west railroad will include 21 km of twin, 6.2-m dia. tunnels under the city. All schedules could change after the government elections, which must be held before June. The opposition Conservative Party,
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.