I - 129 is the shortest state highway at 0.286 miles ( 0.460 km ) in length .
129 is located 4 miles ( 6.4 km ) southeast of US 77 .
I - 129 , which is located 4 miles ( 6.4 km ) southeast of US 77 , is the shortest state highway at 0.286 miles ( 0.460 km ) in length .