Freight railroads, an indispensable part of the North American transportation system, serve nearly every industrial,
wholesale, retail, and resource-based sector of the economy. Based on the latest available statistics, railroads shipped over
1600 million tons of goods in the United States (
DOT, 2013
) and 336.5 million tons in Canada (
TC, 2013
). It is interesting to
note that coordination among over 570 different freight railroad companies, who collectively own and manage the nearly
140,000-mile integrated network, ensure the smooth and efficient flow of freight (
AAR, 2014
). In light of the above, it is
evident that sub-par operation resulting from either malfunctioning infrastructure or temporary track blockage because of
an accident would not only have an unfavorable impact on the customer service but also an adverse effect on the economy.
Such disruptions often necessitate rescheduling and/or rerouting of trains, and invariably result in delayed deliveries since
their exact durations are unknown and difficult to anticipate.
It is interesting to note that disruptions to railroad operations, like those to business operations, are not infrequent (
WS
DOT, 2014; Stecke and Kumar, 2009
). For example, sixty-one disruptions were registered for just the Seattle–Vancouver
Amtrak operation between 2009 and 2013. Such disruptions could either lead to complete cancellation of train services (i.e.,
annulment) for a period of time, or to partial disruption of the train service where the train may be active over only a
portion of the original route (i.e., a set of track segments between consecutive stops called service legs). Note that a train