What was the guage of the concessionaire ferrosur roca?
CREATE TABLE "table_1_privatisation_of_freight_service" (
  "concessionaire" text,
  "fa_division_s" text,
  "gauge" text,
  "length_km" real,
  "takeover_date" text
);
SELECT "gauge" FROM "table_1_privatisation_of_freight_service" WHERE "concessionaire"='ferrosur roca';