Hi peter

Thanks for your grate support in helping solving this problem 

How do you excite the rail in the lab? 

*Using instrumented hammer ( excitation points are only at the top face of the rail )

Do you hit it with a hammer?

* YES 

How did you determine the frequency and mode shape in the lab?

* Using a laser vibrometer (capturing the response only in the vertical direction with its software ( it can give you : time domain or frequency domain )(FFT&FRF)

When are you going to add the spikes?

* The study considers just the rail resting on the sleepers without adding any spikes.