Since conventional rail fasteners for bridge sleepers used in bridge sections do not have the right-left adjustment function of the rail, it is necessary to re-drive the screw spikes to secure rail fasteners to bridge sleepers in order to straighten track irregularities such as alignment defects and gauge irregularities.
      Recently, a new technique to straighten long-wavelength track irregularities has been introduced to improve riding comfort levels. Straightening of track irregularities has frequently been undertaken even in bridge sections. However, this has increased the workload of re-driving screw spikes while leaving many unnecessary screw spikes on the bridge sleepers, leading to deterioration of these sleepers. Particularly, investment in the composite bridge sleepers intended for long-life service has not yet paid off.
      The Railway Technical Research Institute (RTRI) has developed a rail fastener that can readily adjust the right and left rails by setting up a lateral force support device with sufficient durability against lateral pressures even in the bridge sleeper sections, and by making the tie plate hole elliptic (Fig. 1). Using this rail fastener renders re-driving screw spikes unnecessary and can improve the workability and safety of straightening track irregularities without shortening the life of bridge sleepers, including composite bridge sleepers.