As well as your contract I would check that there is no supplemental company policy that applies . Your line manager , local HR rep or union rep (if a member) might be best placed to advise .
My TOC has a policy that any secondary employment (paid or voluntary) has to be declared and there are certain stipulations for commercial reasons around working for compettitors/certain employers , and stipulations for safety reasons that safety critical workers must ensure that their secondary employment does not impact upon their preparedness for duty .
I engage in voluntary work which amounts to about 6 hours a week and thus declared this when the policy came into effect . I was reminded of the need to make sure it didnt impact my work , other than that I am largely left to it but am well aware that if I were to allow my voluntary work to imapct my primary role and was involved in an operational incident I would have many qyestions to answer if I were to cite my voluntary work as part of the cause of the incident .Practically I manage that by ensuring that I do not engage in said voluntary work 12 hours before any safety critical turn of duty .
I know of others in safety critical roles who continue trades they had before on their rest days or similarly carry out voluntary work without issue . I think the biggest challenge will be finding a secondary employer who would be understanding of the needs of your primary job .
If you are driving trains; a guard/conductor; signaller or working on the track; I would not consider a second job. Far too risky in my view. You might feel okay but then you are involved in an incident - how would you explain to your masters.
I have 2 jobs doing what I do and with the commuting on top - it's really tiring. Please think very carefully....
I think this might be a tad extreme . I mean if you have a 5 day long weekend for example and decide instead of volunteering for OT in the day job that you are going to do a day driving a van for a friend who runs a small business then what is the harm in that ?
Absoloutely trying to sqeeze 6 hours of delivery driving in an evening when you have just done a 10 hour turn and have a 4am turn the next day is irresponsible and stupid , but then so would spending 6 hours driving to and from visiting a relative the evening in the same circumstances .
That's the kind of unhelpful intervention that I don't want and fear quite honestly. It's why I would actually be reluctant to bring it up with my manager. To those who are much more trusting of management and suggest telling a manager should be the first port of call, you need to consider that there are also many managers that take an extreme zero-risk-attitude to work. Who am I to say that this approach is wrong or bad for the industry? However, I can tell you that many of these managers are more interested in covering themselves from any possible blame rather than helping anyone or benefits for company/industry/safety as a whole.
It's been really useful for me reading about those of you that have actual experience of working second jobs already and how you manage your main job's around that.
A couple of people have referenced the possibility of incidents and how you would explain your second job if you ever had an incident, but I think that's perhaps not relevant or at the very least a poor measure of someone's fatigue. It's only really relevant if you've been reckless. Others have correctly noted that there are a great many workers that spend most of their spare minutes on heritage railways. That doesn't seem like much of a break to me but it is their choice. Would that fact be relevant if that person had a serious incident? I'd say, no, that's how they like to relax and we shouldn't assume what's stressful for one person is necessarily stressful for another. That's not to say that I don't understand why there is an obvious desire to have some universal set of rules to measure someone's fatigue because it makes things easier to regulate. I just don't think it's a good measure (and may actually have the opposite effect if workers as a result of these fatigue limits have to take on a second job for more money because their working hours are reduced). Will there be less incidents as a result? No. But the same refrain will come, as above, don't blame us, we tried to reduce their fatigue ...
I think a better way for the industry to manage fatigue for its various professions might actually be to develop some kind of individual tests for workers to do before they actually start their duties. If they can pass them, they are likely fit for work. If they fail them they are not and shouldn't come in to work. It would help workers decide if they're fit for duty and work better than trying to police their activities in their spare time. Anyway, food for thought.
Ill be honest if it is something that you are going to do then I think it would be unwise to do without discussing with your manager , and depending on company policy might also be a breach of this and could thus land you in more hot water later down the line . I would suggest also though that finding out the company policy if there is one may be of assistance because it may not explicitly prohibit secondary employment or it may just obligate you to inform your manager without giving the manager the power to say no .
Even if you do not like the answer given by your line manager there are always ways of raising it further if you think that the answer or reasoning is unreasonable .