To expand a little on the LMO topic.
Firstly, in principle Auld Yin is technically correct when he says you are able to hop on a plane, turn up at port of entry armed with your LMO and written job offer and obtain your visa. However, also be advised the ultimate decision in granting your work visa is entirely at the discretion of the immigration officer at port of entry. I am not sure how often refusal happens but believe me it does happen.
To enlighten you on the overall process a little further. The L.M.O. (Labour market opinion) is an authorisation granted by a goverment department to the company applying. In this instance, let us argue this company is CN.
Part of the process of CN applying for the LMO is to prove to the Government department, they are unable to recruit (usually locally) for the position they wish to fill. This inability could be for any number of reasons BUT, and here will lie your problem, the closer the vacancy is to a large populous (city) the more difficult it will be for the company to see an LMO granted.
It is also part of this process the position has to be advertised for a number of weeks prior to the company even being able to submit an LMO application.
It follows, more rurally tends to produce the more successful LMO applications as the local Canadian population and subsequent skill sets will be thinner on the ground.
Taking all of the above into account, this will likely prove your downfall as the more urban positions available within the railway networks will likely receive favourable results from within the companies existing workforce.
On the plus side, I do know there are many vacancies in the more rural areas but here you would firstly have to be sure you and your family were cut out for rural AND that there is a way to apply for these positions in the first place. Please also understand, rural in the UK does not come anywhere near rural in Canada.
In your case, as I think AY has already suggested, your first step would be to talk with CN and CP
Good luck
