Abstract

NedTrain, part of the national Dutch Railway group 
(NS group) is responsible for the tender, maintenance 
and revision of rolling stock. Trains to be maintained are delivered by NS Travelers, 
also part of the NS group. Contracts between NedTrain and NS Travelers specify penalties for 
maintenance jobs that do take too long. 
Arrival of trains (release times of maintenance jobs) 
is quite unpredictable. NS travelers decides 
 supply of rolling stock at the very last moment; Exact duration of maintenance jobs is only known after
 initial inspection jobs, therefore large amounts of uncertainty; Maintenance is performed by a number of teams and 
 each team constructs its own operational schedule.
It is our task to

• design a fast scheduling algorithm for the 
maintenance problem such that rescheduling 
is possible in real-time;
• find total solutions maximizing flexibility of 
maintenance jobs while maintaining makespan;
• find a method to distribute the total maintenance problem 
into a number of independent subproblems, and provide 
an exact metric to determine the associated loss of flexibility.