To solve problems caused by the lateral force between the wheel and the rail on sharp curves (such as wear on the rail side surface, rail corrugation, upright wear of the wheel flange and squealing), lubrication of the top surface of the inner rail is generally regarded as effective. The wheel/rail friction-moderating system (FRIMOS) spreads friction-moderating particles (referred to below as moderators) between the wheel and the rail using a jetting device (Fig. 1).

In a running test of a car mounted the moderator-jetting device on a commercial service line, the RTRI confirmed reduced turning lateral force between the wheel and the rail, and decreased noise level, and that these effects maintained for a while. The average noise level of 85 dB or more before the moderator was spread decreased to about 78 dB or less, and remained at that level until about 250 axles had passed the point where the moderator was applied. This demonstrates that the effect of noise reduction with just a small amount (0.07 g/m) of moderator continues for a certain length of time (Fig. 2).

The RTRI also performed tests to investigate the braking performance and the effect on track circuits of a moderator made of carbon, and confirmed that there were no problems in practical use.

This system is now expected to be introduced by railway operators in Japan.