6Model testing of two-layer railway track ballast. By Wil- liam Fergus Anderson and Andrew John Key Journal of geotechnical and geoenvironmental engineering/April 2000 317-323.
7Higgins A. Scheduling of railway maintenance activities and crews [ J ]. Journal of the Operational Research Society, 1998, 49 : 1026-1033.
8Vale C, Ribeiro I, Calada R. Integerprogramming to optimize tamping in railway tracks as preventive maintenance[J]. Journal of Transportation Engineering, 2012, 137(1) : 123-131.
9Miwa M. Mathematicalprogramming model analysis for the optimal track maintenance schedule [ R ]. Japan: Railway Technical Research Institute, 2002, 43 ( 3 ) : 131-136.
10Zhao J, Chan AHC, Burrow MPN. Reliabilityanalysis and maintenance decision for railway sleepers using track condition information [ J ]. Journal of the Operational Research Society, 2007, 58: 1047-1055.
