Footbridge Dilemma

A dark bridge in the rain. You're leaning on the railing, watching a creek below, when you hear the distant whine of an oncoming trolley. You look down — five workers on the track beneath the bridge, their backs to the rails, replacing ties. They don't hear it. You scream, but the rain swallows your voice. Then you notice the man standing next to you — heavy mountaineering gear strapped to his shoulders, staring quietly over the railing. With his pack, the combined weight would be enough to stop the trolley. A cold calculation forms in your mind: pushing him off the bridge, his body and pack would stop the trolley. He would die. The five would live. There is no lever. The trolley arrives in 12 seconds. Your hand is already hovering inches from his back.