Name of movie begins with motorcycle beheading?

I forget the name of the movie where it starts out in the dark of night. A lone figure is measuring and tightening a long cable across a stretch of road. Soon a motorcyclist is nearing and the lone dark figure flashes a small flashlight where the cyclist lifts his head slightly to see what is in front of him, at the exact time the cable beheads him. What is the name of the movie?
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