The Interstate Commerce Commission maintains records of accident reports involving injury or death to passengers, crew or trespassers due to derailment or collision. Reports available online start in 1911 and continue through the 1960s, however the reports after 1940 do not contain any names and are of rather limited use to genealogical researchers trying to find a specific person. The records that do contain names usually only contain the LAST name (such as "Conductor Smith"), but in some cases much more info is given. The location of the accidents can give clues as to the geographic locale of the individuals, as train and engine personnel rarely strayed from their divisions, and often resided in either of the endpoint towns of the divisions.
Below is my index to the ICC data for the Chicago & North Western Railway from 1926-1940. These indexes are based on my review of 43 separate accident reports. These actual ICC summary reports can be viewed online in HTML and PDF format. Click on the I.C.C. Historical Railroad Investigation Reports (1911-1966) link for a searchable index page. Searching on the ICC report number will probably work best.
The C&NW Historical Society administers archived records from the railroad and those accumulated by the group. They do have someone who will assist with genealogical questions - I don't know the extent of their holdings or costs involved in researching them. You can email their genealogical research assistant for more information. In addition, many of the Society's C&NW employee service cards have been scanned by Ancestry.com and will be available to subscribers.
Listings of company officials and sales personnel can be found in most employee timetables, as well as issues of The Official Railway Guide. Here is a listing for the C&NW from the May, 1984 issue of The Official Guide, North American Freight Service Edition.