Photo Courtesy of MMC-Gamuda Variable-density-slurry tunnel-boring machine was developed to dig through fissured limestone. Last month, it broke through on a transit project in Kuala Lumpur. Related Links: Kuala Lumpur-Singapore High-Speed Link Plan Draws Global Interest Dual Purpose Tunnel Becomes Smart Solution A new type of tunnel-boring machine designed to excavate through fissured limestone recently made its global debut with a breakthrough on Kuala Lumpur's emerging mass rapid-transit system. Six new variable-density-slurry tunnel-boring machines (VDTBM) are deployed on the 9.5-kilometer-long twin drives of the Malaysian capital's notoriously difficult karstic ground.With the first VDTBM drives completed this January, the technology "is
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.