Boston's Big Dig (1991–2007)
Boston buried its elevated Central Artery highway in a tunnel and built a new harbor crossing, rebuilding the region's main freeway in place. The work dragged on for more than 15 years, with chronic lane shifts, closures and congestion across downtown.
It finished in 2007 at a final cost around $14.6 billion, far above early estimates.
It became the national cautionary tale of cost overruns in urban highway construction.
Utah's I-215 rebuild follows the same pattern of rebuilding a busy highway in place — smaller in scale, but with the same months-long disruption.
