Mergers of major railroad companies in recent years resulted not only in the merging of different railroad lines and operating rulebooks, but also in the merging of railroad cultures and operating practices. Superficially, it may appear that most railroads have adopted a common code of operating rules, but major differences still exist in the application, and consequently, the compliance with these operating rules. Moreover, different management styles often clash when organizational cultures merge, as documented in the case of the Penn Central merger in 1968 and the Burlington Northern Santa Fe merger in 1995. This leaves operating rules managers uncertain as to how specific rules should be applied on their newly formed railroad. Different management philosophies may also influence different compliance standards across railroads.