Hiring Session Invitation For Union Pacific Bridge Tender

I just received a Hiring Session Invitation for Union Pacific Bridge Tender. Can anybody here tell me anything more about the job? For example, are these likely to be shifts of 8 hours, 10 hours, or 12 hours? I assume it would be mainly afternoons or midnights. Are they generally a fshift or might the hours change frequently? Is this a good position and are there other opportunites in the future?