Several types of diesel locomotive have been tested on this working and as a result the probable choice will be Type 2 diesels in pairs, without bankers. The crucial factor in the selection of this method is the higher degree of adhesion obtained than with a single Type 4; on trial one of the latter showed that in very adverse conditions it might slip to a standstill at one of the two tricky spots on the steep climb from Tyne Dock to Consett.