As the deadline draws nearer for passing a new surface transportation bill—or at least approving another extension—lawmakers are seeking ways to augment the shaky Highway Trust Fund. Highway and transit programs have been operating under short-term measures for nearly 20 months because Congress has been unable to produce a new, multiyear authorization. The latest stopgap measure expires on Sept. 30. Another deadline is looming sometime around fall 2012, when spending from the trust fund's highway account is projected to start exceeding its income. The Senate Finance Committee, which oversees the trust fund, “has already started to think creatively” about transportation
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.