Two formations of adjustment gangs mainly using a Plassar multiple tie tamper are applied to Northern Line to perform continuous adjustment approximately once a year. Surface, alignment, and circularity are attentively adjusted in the daytime by fully using an automatic inspection / adjustment system.
(b) Repair of track materials
Because the existing track specifications are low-level, upgrading of the specifications is assumed to be progressed. However, it seems that repair of components for the existing specifications is generally satisfied. It seems that a sufficient amount of track ballast is replenished and wooden sleepers and tie plates are kept at a sound level. Partial replacement of wooden sleepers is most frequently performed as the routine material replacement.
(c) Long welded rail
1/ A 144 m rail is made from 18 m rails by the factory flash butt welding and the long welded rail is completed from these 144 m rails by thermit-weldt at a work site.
2/ A long welded rail generally has a length equal to the distance between stations. The long welded rail normally has a joint at its end.
3/ A 18 m rail is used for a mountainous section without using a long welded rail not because of the prevention of buckling of a track but because of the profitability for maintenance including rail replacement. Because a temperature change is small, it is possible to change a 18 m rail to a long welded rail.
However, it is necessary to replace a rail in a short period because of one-side wear of the rail. When a long welded rail is used, a lot of labor is required for replacement compared to the case of a 18 m rail at present. Therefore, the maintenance work amount cannot be decreased even by using a long welded rail.
