Most of the time a company will be looking for you to make a nod to their branding, recent events and history. In hard circumstances such as redundancy, lack of work etc (think Freight companies as an example) then it is OK to mention this -
but I would shy away from softer reasons like not getting on with your colleagues, shift patterns or a change in working patterns.
They're all perfectly normal reasons, but could be misinterpreted as a lack of flexibility.
Remember that in most cases when you are applying to a company your first point of referral will be the HR team, rather than train crew / production managers etc. So tailor it with that in mind.