Under these circumstances, maintenance will become extremely costly. Therefore, it is necessary to reduce manpower by using machines for many of the maintenance duties and inspections, and to make the work itself more appealing.
1.5 A Better Environment
Railways are primarily a low-pollutant mode of land transport compared to automobiles.
Social problems can result from noise pollution, vibrations and the emission of excrement from passenger trains, and these tend to arise alongside increases in transport volume, higher train speeds and social progress. Necessary action must be taken to deal with these problems for people living along the railway line, and track improvement is an effective countermeasure.
2 Railway Modernization and Tracks
To implement the railway modernization described above, the following points must be considered in the field of track:
2.1 Safety against Overturning and Derailment
(1) Overturning along Curves
The maximum speed of trains is subject to restrictions along curves in accordance with the curve radius. Trains overturn if the resultant force of gravity force and centrifugal force imposed on the cars acts outside the tracks. The maximum speed on curves is determined taking into account a safety factor of three to three and half times against overturning.
Cant has close relation with train speed. Cant is set taking into consideration the train speed, unbalanced cant, riding comfort and overturning on the inside of the curve while stopping.
The maximum speed restriction on curves is being eased recently by introduction of pendulum cars.
(2) Derailment
Derailment occurs when the ratio of wheel load and lateral force acting between the wheels and rails exceeds a certain limit (normally 0.8) for a specific period of time. As a result, it is dangerous when there is a simultaneous decrease in wheel load and increase in lateral force due to reasons such as car vibration caused by dynamic interaction between track and running car. Track geometrical irregularities on tangent sections or curves is a major controlling factor.
