It was truncated to the junction of I-93 and I-95 in Canton in 1997; despite no longer carrying this designation, the split continues to be informally recognized as the starting point of Route 128 within Massachusetts.

[3] 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)[4] and Plymouth (492,066 residents)[4] counties, partly due to the 1973 cancellation of the planned Southwest Corridor alignment of Interstate 95 into Boston.

Similarly, Boston traffic bound for cities and towns in southeastern Massachusetts including western Norfolk and Bristol County (545,823 residents)[4] and in Rhode Island negotiate the Braintree Split prior to continuing along Route 24 or Interstate 95.

Short weaves, lane drops and line-of-sight problems all contribute to congestion in the interchange and the highways it serves.