North–South Rail Link
The North–South Rail Link (NSRL) is a proposed rail tunnel, or pair of tunnels, that would connect North Station and South Station in downtown Boston, Massachusetts, linking rail networks that serve the city's northern suburbs, New Hampshire, and Maine with the rest of the country. The project would build new underground stations near the existing stations, connect them with about 1.5 miles (2.4 km) of tunnels, and add other tunnels to link up with existing surface tracks.