1Class I Railroad Statistics. Association of American Railroads [Z].2010.
2Evans,D.S.,Heckman,J.J.A Test for Subadditivity of the Cost Function with and Application to the Bell System[J].Amefican Economic Re- view, 1984,74(4).
3John Bitzan.Railroad Cost Conditions--lmplications for Policy, Pre- pared for th Federal Railroad Administration, U.S. Department of Transportation[Z] .2000.
4Winston,C.,Corsi,T.,Grimm,C.,Evans,l.The Economic Effects of Sur- face Freight Deregulation[M].Washington, DC: Brookings Institution, 1990.
5Friedaender, AF.,Spady, RH.Freight Transport Regulation;Equity, Ef- ficiency, and Competition in the Rail and Trucking Industries[J].Bell Journal of Economics, 1980,8(2).
