Brilliant minds—Nikola Tesla, Thomas A. Edison—and great engineers produced the marvel of the electric grid. It has united and fed the vast complex that is modern industrial and post-industrial society. But like the Scarecrow in Oz, the grid lacks a brain. Advances in electronics, communication and information technology now are enabling engineers to give the grid a brain. In the last decade, grassroots initiatives have sprung up around the country to create what has come to be called the smart grid. In a smart grid, sensors can anticipate system disturbances and respond to them before they cripple the system. Communication
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.