The Bridge-Tunnel project is a four-lane 20-mile-long vehicular toll crossing of the lower Chesapeake Bay. The facility carries US 13, the main north-south highway on Virginia's Eastern Shore, and provides the only direct link between Virginia's Eastern Shore and south Hampton Roads, Virginia.
The crossing consists of a series of low-level trestles interrupted by two approximately one-mile-long tunnels beneath Thimble Shoals and Chesapeake navigation channels.
The manmade islands, each approximately 5.25 acres in size, are located at each end of the two tunnels. There are also high level bridges over two other navigation channels: North Channel Bridge and Fisherman Inlet Bridge. Finally, between North Channel and Fisherman Inlet, the facility crosses at-grade over Fisherman Island, a barrier island which includes the Fisherman Island National Wildlife Refuge administered by the U. S. Fish and Wildlife Service. Toll collection facilities are located at each end of the facility.
(Source: http://www.cbbt.com/facts.html)
