The Career Fair is for those students who will be graduating later that year and looking to work for the UP in jobs/careers other than TE&Y (read Corporate, Management, Accounting, Sales, IT, etc.). The UP only goes as far east as Memphis and they do not actively recruit college students outside of the western third of the country for TE&Y positions. As a former engineer with UP working for Amtrak, you would be better suited to look for the TE&Y jobs on the UP website, apply on-line and then travel/fly to the location where the UP is hiring for said TE&Y position. And be sure you wish to work/live within that city/region. Once you are hired on within that UP Subdivision, you will find it is an uphill climb (nearly impossible, and why I quit to go to Amtrak) to transfer elsewhere.
Since this a college recruiting event, dress the part.