THE LAST day of regular service for ‘D’ stock on London Underground’s District Line is scheduled to be 21 April, when the last six units in operation will be withdrawn. A special run with the stock is planned for 7 May.

All 192 ‘S’ stock trains for LU’s sub-surface lines have been delivered, although up to 10 are away at Bombardier’s works in Derby at any one time for fitment of the Thales automatic train operation system being brought in on the sub-surface network. The first train fitted with ATO, No 21050, was back in service in early March, ready for use on the first section on which the ATO is due to go live next year, the western end of the Hammersmith & City Line.

LU has plans to convert two redundant ‘D’ stock trains from the District Line into rail adhesion trains (RATs) for use on the Metropolitan Line. The Met currently has a single RAT to treat the rail head during the autumn, which is life expired, and LU believes the demand for adhesion coverage will increase when automatic train control is introduced on the line. It therefore plans to convert the redundant D stock trains and modify the sandite filling platform at Neasden depot to support the introduction of two new RATs. The modifications to the D stock trains will be carried out by LU’s Trains Modifications Unit at Acton works.

In addition, an adhesion train for the Piccadilly Line is to be provided by converting existing 1973 stock trains. LU plans to take one train out of service for up to six months each year and undertake a temporary conversion to create 2x3-car RATs; this will involve fitting a sandite dispensing module. One train will treat the track between Cockfosters and Arnos Grove and the second between Northfields and Osterley; the Rayners Lane branch will be supported by the Metropolitan Line RATs.

The Piccadilly fleet has been vulnerable to wheel damage in low adhesion conditions, and LU reports abnormally high levels during the last two leaf-fall seasons.

In late 2016 almost half the fleet was withdrawn from service for repairs to damaged wheels. In addition to using the adhesion trains, LU plans to implement a leaf-fall timetable on the Piccadilly Line to incorporate operation of adhesion trains and to accommodate a reduced brake rate and any temporary speed restrictions.