Development of an Optimization Model and Algorithm Based on Transportation Problem with Additional Constraints

추가 제약을 갖는 수송문제를 활용한 공화차 배분 최적화 모형 및 해법 개발

  • Park, Bum Hwan (Department of Railroad Management and Logistics, Korea National University of Transportation) ;
  • Kim, Young-Hoon (Logistics System Research Team, Korea Railroad Research Institute)
  • Received : 2016.12.06
  • Accepted : 2016.12.21
  • Published : 2016.12.31


Recently, in the field of rail freight transportation, the number of trains dedicated for shippers has been increasing. These dedicated trains, which run on the basis of a contract with shippers, had been restricted to the transportation of containers, or so called block trains. Nowadays, such commodities have extended to cement, hard coal, etc. Most full freight cars are transported by dedicated trains. But, for empty car distribution, the efficiency still remains questionable because the distribution plan is manually developed by dispatchers. In this study, we investigated distribution models delineated in the KTOCS system which was developed by KORAIL as well as mathematical models considered in the state-of-the-art. The models are based on optimization models, especially the network flow model. Here we suggest a new optimization model with a framework of the column generation approach. The master problem can be formulated into a transportation problem with additional constraints. The master problem is improved by adding a new edge between the supply node and the demand node; this edge can be found using a simple shorted path in the time-space network. Finally, we applied our algorithm to the Korean freight train network and were able to find the total number of empty car kilometers decreased.


Supported by : 한국철도기술연구원


  1. Korea Railroad (2009) Development of Optimization System for Rail Freight Transportation. Interim report, Korea Railroad.
  2. R. K. Ahuja, K.C. Jha, and Jian Liu (2007) Solving real-life railroad blocking problems, Interfaces, 37(5), pp.404-419
  3. A. Fukasawa, M. Aragao, O. Porto and E. Uchoa (2002) Solving the Freight Car Flow Problem to Optimality, Electronic Notes in Theoretical Science, 66(6), pp. 42-52.
  4. M. Joborn, T. G. Crainic, M. Gendreau, K. Holmberg and J. T. Lundgren (2004) Economies of Scale in Empty Freight Car Distribution in Scheduled Railways, Transportation Science, 38(2), pp. 121-134.
  5. A. K. Narisetty, J. P. Richard, D. Ramcharan, D.M. Murphy, G. Minks and J. Fuller (2008) An Optimization Model for Empty Freight Car Assignment at Union Pacific Railroad. Interfaces, 38(2), pp. 89-102.
  6. B. Lee, D. Won, C. Ahn, B. Park (2016) Status of empty freight car operation, Proceedings of the Korean Railway Association Fall Conference, Jeju, pp. 85-93
  7. O. Ha, K. Kim, H. Kong, S. Choi (2013) Calculation of appropriate return days for securing the objectivity of judgment of wagon quantity required, Proceedings of the Korean Railway Association Fall Conference, Daegu, pp. 108-115.