The broadening effect of the reflective spectrum of fiber Bragg grating(FBG) under uneven strain distribution is verified by experiments,and such a effect is applied to measure the wheel weight,train location and axle counting.The FBG sensor can be placed at the specific location of the rail.The reflective spectrum of the FBG will be broadened under uneven strain induced by the weight of the wheel,so the detected optical power increases.Spectral variations under temperature,even and uneven strain distributi...