Question: What is the smallest amount of freight carried on the road that closed on march 31 and reached super B capacity on february 17 after 2011?
SQL: SELECT MIN("Freight Carried s Tonne") FROM "2-12791809-1" WHERE "Road Closed" = 'march 31' AND "Super B Capacity Reached [ citation needed ]" = 'february 17' AND "Year" > 2011.0;