Development of the Next Generation Turnout

摘要

Turnouts are one of the weakest infrastructure components of railways. The structure of turnouts is complicated and delicate because they have moving and crossing parts. These make turnout maintenance costly. Turnouts are also apt to cause many troubles which lead to train delays. Accordingly, we have developed the "Next Generation Turnout (NGT)" to prevent any troubles and to reduce maintenance costs and workloads. We completely innovated on the structure of turnouts considering a turnout and a switch machine as one system, solving the problem for maintenance affairs which we were facing with, and referring to the excellent parts of foreign turnout designs. Representative contents of a switching part of the NGT are a small and lightweight switch machine on one sleeper, an inner fastening clip for stock rails, a high level slide base plate which can avoid small obstacles disturbing between a stock rail and a tongue rail, a ball bearing base plate which needs no lubrication, the Grid Sleeper which is a high strength, and maintenance-free switching rods and bars. Moreover, we have developed or used a tongue rail of which shape of tip is improved to strengthen, a wing rail which is less damaged by wheel impact loads in spite of a welded frog made of rails, an insulating glued joint which lets turnouts use in the continuous welded tracks, and so on. This paper is also described for performance on maintenance of the NGT in three points of view. First, it is described for performance of that how to prevent switch failures. We estimate that the number of switch failures of the NGT will decrease about 90 % compared to conventional turnouts. Secondly, we refer to the extension of terms of maintenance. For example, an interval of inspection will grow up to 2 times in maximum and that of replacement of a switch rail will increase to 3 or more times. Finally, workability is enormously improved by using the NGT. Adjustment of switch rods or bars is eliminated, and that of locking system becomes simplified. A prototype of the NGT was mounted at Omiya station yard on Takasaki Line in the suburb of Tokyo in February 2002. After 4 years passed, the NGT is performing very well without any troubles and maintenance. Currently, the NGT was mounted more than 50 sets from 2003 to 2005 around Tokyo Metropolitan area. JR East intends to mount the NGT more than 1000 sets for some years. We consider that the NGT prevents many troubles and reduces maintenance costs and workloads sharply. We recommend this new type turnout for many railway operators.