Here is their employment website.....
looks like now you can apply online
Appears that these are the locations you can apply for
Iowa City, Newton, Council Bluffs, Cedar Rapids, Rock Island, Blue Island (Chicago)
Hope that helps you out!
Also found some things from August job postings
Conductors - (2) Council Bluffs, (3) Rock Island and (2) Iowa City Hourly Position
Iowa Interstate Railroad, Ltd., has full-time Conductor positions available. Duties will include operating track switches, coupling and uncoupling cars, coordinating train assembly, and following safety rules and regulations required by the Railroad and federal government to transport freight in a safe, efficient and satisfactory manner. Schedule will include time away from home, varied hours, weekends, and/or holidays. A valid Driver’s License and High school graduate or equivalent is required. Knowledge of railroad transportation a plus.