During the summer and fall of 1968, the Boston & Maine ran a conveyor belt of gravel trains in the form of three trips a day carrying fill for a big highway project from a pit at Bow, NH, to a construction site at Revere, MA. The B&M's older power was usually assigned to these jobs. Here RS-3 1535 and F3A 4228A lead a train of empties headed back to the pit, northbound at West Medford, MA.