Boston's Big Dig (1991-2007)
The Central Artery/Tunnel Project buried a major interstate highway under downtown Boston, replacing elevated roadways with underground tunnels. Construction caused years of traffic shifts and disruptions across the city.
Massive traffic delays and cost overruns, with the final price exceeding $14 billion.
The Rose Kennedy Greenway, a linear park, now sits on the former highway surface, improving walkability and linking neighborhoods.
Demonstrates that temporary closures can yield permanent public green space, a key benefit of the Northland tunnel.
