Final answer:
The question involves railway engineering and refers to the specifications or procedures concerning holes in railway sleepers after cut spikes are removed. It likely addresses the dimensions or the method of treatment for maintaining tie integrity.
Step-by-step explanation:
The question pertains to railway engineering and specifically to the maintenance of railway ties (sleepers). When cut spikes are removed from a railway tie, there is a procedure or a specification for the hole that remains.
This could involve the diameter of the hole, the process of treating or filling it to maintain the integrity of the tie, or standards for when the tie should be replaced. In the context of railway maintenance, cut spikes are typically large nails with a flat blade used to secure rails to the wooden tie. When these spikes are removed, it might be necessary to either plug the hole or replace the tie depending on its condition and the standards set by the railway authority, which could be indicated by the numbers (15-170) in the question, although without additional context, the precise meaning of these numbers is unclear.