A down economy could provide a positive boost to opponents of looming targets for construction- equipment emissions in California. A new study suggests formulas that were used by the California Air Resources Board (CARB) to establish future emissions-reduction targets overestimated the levels of nitrogen oxide and particulate matter from off-road diesel equipment in the state. AGC says looming equipment emissions rules are based on projections now reduced by compliance and the recession. The findings are based on new data released from an inventory of construction equipment currently in use in the state conducted this year by the Sacramento-based board. The
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.