During 1990 a similar exercise to that undertaken the previous year for the Central Line was undertaken for LUL with regard to the planned introduction of new rolling stock for the Northern Line. This time a total of five sites were considered in respect to maintenance and stabling, (Golders Green, Morden, Edgeware, High Barnet, and Highgate) many of these sites being severely constrained in terms of road access and space available.

Again the need to overcome the imbalance between unplanned to scheduled maintenance figured heavily in the exercise with the content of the study being broadly as that identified for the Central Line above.