There’s no getting around the fact that automobiles are among the leading causes of pollution. There are tens of millions of cars and trucks on American roads contributing significant amounts of greenhouse gases to the atmosphere. The question facing policy makers, scientists, and engineers is how to reduce the impact that our vehicles have on the environment. In Washington, the discussion revolves around how high to raise fuel efficiency standards and whether to offer tax credits to those who drive hybrids and alternative fuel vehicles. And on the drawing boards of auto industry engineers and environmental scientists, new ideas 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.