2Ronald S Koot, John E Tyworth. The determinants of railroad track maintenance expenditures: A statistical analysis[J]. Transportation Journal, 1981(Fall): 24-43.
3Phill Wheat, Andrew Smith. Assessing infrastructure maintenance wear and tear cost railway network[J]. Journal of Transport Policy, 2008(5): 189-224 the marginal for Britain' s Economics &Policy, 2008(5). 189-224.