- Improvement at a scale of 100 curves and 40 km has been made since nearly 10 years starting with a section with preferable conditions of margin in railway formation and topographic form. Improvement of about 90 curves and 22 km is further scheduled by 2000.
- These improvements are also progressed mainly by the effort of the above permanent-way maintenance division and 3/4 of the sharp curves with a radius of less than 300 m will be improved for approx. 60 km including already improved curves.
In the above phase, curves with a radius of less than 300 m will be left for sections of 20 km under a severe topographic condition.
3.4.5 Level for track adjustment
(1) Management of adjustment level by measured value
- Values measured by a track inspection car twice a year are totalized for each section in charge of maintenance. Moreover, a target level is individually studied for each section and thereby, adjustment levels are managed.
- A level is evaluated in accordance with an index value (Quality Index) obtained by weighted-processing for each track adjustment item. In the case of recent measurement examples, the QI value shows 15 to 20 for a flat area and approx. 25 for a mountainous sharp curve area which are high levels.
- A target value for each section in charge of maintenance is set twice a year by considering various conditions related to actual works and judging from experiences and used for effective works.
(2) State of circularity adjustment
In the case of three examples showing the results of adjusting sharp curves in general, the planned versine calculated by the versine method shows that the difference between adjacent values is 0.5 mm and the versine form of the overall length of a curve is preferable.
