CREATE TABLE table_21959 ("Name" TEXT, "Map colour" TEXT, "First operated" FLOAT, "Type" TEXT, "Length" TEXT, "No. Sta" FLOAT, "Current Stock" TEXT, "Future Stock" TEXT, "Trips per annum  ( \\u00d71000 ) " FLOAT, "Avg. trips per mile  ( \\u00d71000 ) " FLOAT)

When turquoise is the map colour what is the length?
SELECT "Length" FROM table_21959 WHERE "Map colour" = 'Turquoise'
SELECT "Length" FROM "table_21959" WHERE "Map colour" = 'Turquoise'