A WAKEFIELD POLICE OFFICER examines the wreckage of a Komatsu excavator in the wake of a train crash at the Forest Street crossing in Greenwood on Jan. 16, 1996. A Mack truck pulling a low-bed trailer carrying the the excavator got stuck on the tracks at about 5:30 p.m. as a train out of Boston was approaching with about 800 commuters on board. The gate attendant frantically waved flags at the approaching locomotive, but the express train, which did not have a scheduled stop in Greenwood, struck the trailer at about 40 mph. The excavator was thrown about 150 feet, landing on its side on the other set of tracks. The locomotive derailed but did not tip over. Several passengers were taken by ambulance to area hospitals. One woman was taken by MedFlight to Boston City Hospital. Many others were treated at the scene for bumps and bruises.