CREATE TABLE table_20188 ("Class" CLOB, "Wheel Arrangement" CLOB, "Railway" CLOB, "Number at Doncaster" FLOAT, "Number at Pyewipe" FLOAT, "Number at March" FLOAT)

Name the railway when class is j15
SELECT "Railway" FROM table_20188 WHERE "Class" = 'J15'
SELECT "Railway" FROM "table_20188" WHERE "Class" = 'J15'