The Braintree Split is the interchange of Interstate 93/U.S. Route 1 and Massachusetts Route 3 located along the city line separating Braintree and Quincy, Massachusetts. The Braintree Split was also the southern end of Route 128 until 1997, when Route 128 was truncated to the I-95/I-93 intersection in Canton. Weekday traffic volume through the intersection averages 250,000 to 275,000 vehicles per day. The term "Braintree Split" is used as a focal point in all local radio and television traffic reports.
Boston's southern gateway
The Braintree Split, technically a "Directional T" type of interchange, is the main road gateway to the South Shore region of Massachusetts, making it a critical point in Boston's highway system. The Southeast Expressway is the single limited access highway traveling south out of Boston, carrying traffic from the city destined for communities in populous Norfolk (659,909 residents) and Plymouth (492,066 residents) counties, partly due to the 1973 cancellation of the planned Southwest Corridor alignment of Interstate 95 into Boston. Drivers other than those headed for parts of Milton and Quincy which straddle the Expressway traverse the split to connect with Route 3 and Route 24 traveling to the more southern localities. Similarly, Boston traffic bound for cities and towns in southeastern Massachusetts including western Norfolk and Bristol County (545,823 residents) and in Rhode Island negotiate the Braintree Split prior to continuing along Route 24 or Interstate 95. Finally, Route 3 serves as the primary freeway route to Cape Cod from Boston's Inner Core. Travelers headed north from these destinations into Boston via I-93 likewise encounter the interchange in Braintree.
Factors local to the Braintree Split contribute to chronic congestion at the interchange. The split is bordered on the south by South Shore Plaza, a major regional shopping mall. It is adjacent to the I-93 intersection with Route 37/Granite Street in Braintree which feeds retail, lodging, manufacturing and office complexes along Wood Road and Forbes Road, which run parallel to the north and south lanes of I-93 west of the split. The Crown Colony office complex in South Quincy and office buildings on Willard Street, the northern continuation of Route 37/Granite Street into West Quincy, are also accessed from the south via ramps at or next to the split. Short weaves, lane drops and line-of-sight problems all contribute to congestion in the interchange and the highways it serves. In addition to these issues, the split also serves the Quincy Adams subway station and Burgin Parkway, a major route into downtown Quincy, through ramps exiting the directional ramps for each roadway.
- Yankee Division Highway Historic Overview bostonroads.com.
- "I-93/Southeast Expressway/Route 3 (Braintree Split): Operational Assessment and Potential Improvements" Boston Region Metropolitan Planning Organization, March 2006, p. 3.
- Weinreb, Michael, Traffic Report, Boston Magazine, May 2002.
- "Table 5: Annual Estimates of the Resident Population for Minor Civil Divisions in Massachusetts, Listed Alphabetically Within County: April 1, 2000 to July 1, 2008" (Microsoft XLS). U.S. Census Bureau. Retrieved 2009-07-27.
- Note: Interstate 93 and U.S. Route 1 run concurrently from Canton to Charlestown in Massachusetts. For this article, "I-93" refers to both routes running together in the Boston area.