| These tunnel off-ramps were built by the Central Artery/Tunnel (Big Dig) project in Boston. The area occupied by these new ramps are known as 'Parcel 12' for upcoming greenway developments. Ramp CN-SA opened to traffic in Mar 2003 and CS-SA was opened in Dec 2003 during I-93 SB opening phase. Construction of both ramps were fully completed in 2007. |