Many countries will only grant work permits to people with skills that they need. For instance, I'm a truck driver and I know from experience that it's relatively easy to get a work permit in Canada but practically impossible to get one for the USA. This is because Canada has a shortage of truck drivers, and the USA doesn't. Some Canadian provinces narrow the criteria even further by only allowing drivers that will do long distance work. So, if I were you, I'd start by trying to find a country that wants your skills and experience on the railway. Another question is are your skills transferable? For example, Doctors can move fairly easily because disease, illness and treatment are pretty much the same where ever you go. Lawyers, however, can't move at all because most legal systems are different and very complex. They'd have to start again from scratch.
You should also consider your personal circumstances. If you're married, there's no guarantee that your partner will get a work permit. Your health is relevant too, for instance Canada has government funded health insurance, and places restrictions on immigrants with pre-existing health conditions. A criminal record will almost certainly rule you out, as will any history of drug or alcohol addiction
And, sadly, many qualifications and certificates you may have could be worthless in another country. Some are recognised (medical qualifications, for instance) but most are not. They will have their own standards and practices and will definitely require you to adhere to them so you could have to start again from scratch. Again using personal experience as an example, countries will recognise each others driving license, so these can be "flipped" easily. Simply go to the local equivalent of the DVLA and hand in your UK licence to get a new local one. Vocational licences like HGV are different, you have to have training and take a driving test for the class of vehicle you wish to drive. I also had an ADR certificate which meant I could carry chemical products anywhere in Europe, but it was worthless in Canada