Section 8C. Any contract for the resurfacing, maintenance, minor reconstruction or minor repair of any major state highway or numbered route within the city of Boston, between said city and state highway route 128, of state highway route 3 as far south as the junction of state highway route 139, on which the average daily traffic exceeds 70,000 vehicles per day, and any contract for the maintenance, minor reconstruction or minor repair of state highway route 128 between its junction with state highway route 3 in the town of Braintree and its junction with United States route 1 in the town of Lynnfield, to be awarded by the division of highways, the department of conservation and recreation or by a municipality under section 34 of chapter 90 shall, unless such contract involves the performance of emergency work as described in this section, provide that no work shall be performed between the hours of 6:30 and 9:00 a.m. on lanes inbound to the city of Boston or between the hours of 4:00 and 6:00 p.m. on lanes outbound from the city of Boston, Monday through Friday, except holidays. No such work, except emergency work, shall be performed on such a highway or route by a public employee during such hours. As used in this section emergency work shall include only those projects immediately necessary to ensure the safety of persons using such highways or routes.