Hi all -- My experience is the the glue joint between the ties and the road bed is what really holds the spikes. I have been doing hand laid track on cork roadbed for more than 20 years, and I have never had a spike come loose on its own. Once ballast is added and more glue hits the ties, spikes are almost impossible to remove... In the past, the spikes I used barely penetrated beyond the ties anyway. Now I use the Walthers (made by Shinohara?) spikes which are longer, sharper and more consistent than any I have used before without being significantly more expensive.
Bill Winans ----------------------------------- A good friend and O scale modeler, used Upson board for his entire layout's roadbed, all handlaid track and the spikes have held well for over 10 years now. Bud Rindfleisch
