Avenue opened in 1959. The highway gradually became more and more congested as other highway projects meant to complement the Artery were canceled. These included the Inner Belt project, which would have taken through traffic off the Artery and the Massachusetts Turnpike Extension coming in from the west. The Southwest Expressway would have been the route of Interstate 95 from Canton into Boston, and would have tied into the Inner Belt of I-695. Modifications of the above-ground Artery, which was in service until its demolition in 2003 included an additional interchange for the Massachusetts Turnpike (Mass Pike) extension that was completed in 1965, the removal of several on and off-ramps and the reworking in the late 1980s of the Tobin Bridge interchange. The Central Artery North Area (CANA) project placed the above ground ramps from the Artery underground into the City Square Tunnel in Charlestown and resulted in a reworking of the interchange at the north end, placing the northbound offramp from the east side to the west side, and eliminating dangerous weaving across the lanes of the Charlestown High Bridge, which required traffic coming from Storrow Drive and wanting to go to Charlestown to cross three lanes of traffic in only a tenth of a mile. In September 2017, a new park was opened beneath the Central Artery adjacent to the Ink Block section of Boston's South End. The $8.5 million park has a dog park, new lighting, boardwalks, murals, and 175 parking spaces. The artwork in the public space was created by street artists from around the United States. Exit lists The original Central Artery did not have any exit numbers. These were added after the roadway was designated as I-93 in 1974. Many of these exits either do not exist or no longer resemble their original forms. Exits 19, 21, and 25 were completely eliminated. 16 and 18 (formerly exits 20 and 26) were separated northbound and southbound; 16 (former exit 20) northbound uses the old exit 19 location in South Bay, while southbound begins at the portal to the renovated Dewey Square Tunnel (now completely enclosed by Big Dig construction; 18 (former exit 26) northbound begins just shy of the tunnel exit onto the Zakim Bridge, while 18 (former exit 26) southbound is located in Charlestown's Sullivan Square near northbound exit 20 (formerly exit 28) at the portal to the double decked section of I-93 and