State transportation officials and construction firms are hoping that shortly after Congress returns from its summer recess, lawmakers will extend the federal motor-fuels tax as well as the federal highway and transit programs. But Congress will have to move quickly: When legislators go back into session after Labor Day, there will be only 11 legislative days before the gas-tax and highway-transit authorizations expire on Sept. 30.Industry officials are hopeful Congress will act in time. Greg Cohen, president of the American Highway Users Alliance, says, "I think there's broad agreement on the need to extend the gas tax. it's not controversial."
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.