Opponents of the Intercounty Connector have appealed a federal judge's decision to allow construction of the highway.

Environmental Defense, the Sierra Club and the Audubon Naturalist Society filed an appeal Monday with the 4th U.S. Circuit Court of Appeals in Richmond. They are seeking to overturn a November ruling by U.S. District Judge Alexander Williams Jr., who rejected arguments that federal and state planners did not properly study the impact the 18-mile highway would have on the environment and the health of residents living nearby.

The state has already begun construction of the six-lane roadway, which is to connect Interstate 270 in Montgomery County with Interstate 95 and U.S. 1 in Prince George's County.