Negotiations between environmental groups and Georgia Gov. Roy Barnes (D) over how to balance air quality and road-building in the Atlanta metro area collapsed this week. The two sides were close to an agreement that would have lifted a freeze on road-building if the state cut emissions from diesel generators and construction equipment, began to test car emissions more frequently, and moved more quickly to construct high-occupancy-vehicle lanes and study the health effects of the region’s air pollution. But the discussions faltered because Barnes wanted the groups to guarantee that they wouldn’t go to federal court in the future to try to spur enforcement of the agreement. Enviros said they did not trust the state to comply to the terms without the possibility of court oversight.