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.
SR 129 starts in downtown South Boston at an intersection with southbound US 501, which comes from the northwest as a two-way street called Wilborn Avenue and then becomes a one-way street as it heads south. SR 129 continues northeast on Main Street, where its next intersection is with northbound US 501, which follows one-way Broad Street.