sentences:  SR 129 is the old alignment of US 501 and its predecessor, old SR 18, in central Halifax County.SR 129 begins in downtown South Boston at an intersection with southbound US 501, which comes from the northwest as two-way Wilborn Avenue and heads south as one-way Main Street.SR 129 heads northeast on Main Street, whose next intersection is with northbound US 501, which follows one-way Broad Street.