 Eventually, the problem was solved by the electrification of the line between Christchurch and Lyttelton in 1929 when the EC class entered service.The isolated Nelson Section received four WF class locomotives from the 1920s onwards to replace its stud of smaller locomotives, primarily the D class 2-4-0T and FA 0-6-2T tank locomotives.These locomotives were smaller than the WF class locomotives, and the arrival of the larger engines allowed for the smaller D and FA class locomotives to be withdrawn, and in the case of the D class engines, transfer to other parts of the NZR network or sale to industrial users.