| On the basis of known research results, considering switch rail irregular in switch region , higher and wider from switch point to heel of switch rail, wheel/rail contact solid model of switch region is established taking 18th turnouts on the special line for passenger train a example with worn—tread wheel. A careful analysis is made on contact stress of wheel/switch rail and wheel/stock rail when wheel flange close to rail from 20mm-switch rail head section to 50mm-switch rail head section. Not only "single-point contact" and "two-point contact" would happen, but "three-point contact" could happen occasionally between wheel and rail. Vertical force on the switch rail have a transition at some proportion in this region.Contact stress of four transversal sections are analyzed such as 20mm-switch rail head section,30mm-switch rail head section,40mm-switch rail head section,50mm-switch rail head section. It points out contact stress variable discipline in this region by contrast with each other. 20mm-switch rail head section and 50mm-switch rail head section are selected and analyzed some influence coefficient such as lateral movement,friction coefficient,wheel load,base restriction condition and lateral,vertical stiffness on wheel/rail contact stress and so on. All above would be expected to establish a theory foundation to decide permitted speed crossing turnout and meliorate the structure design of turnout.The results show contact position have the greatest influence on wheel/rail contact stress and wheel load secondly. Others such as friction coefficient,base restriction condition and so on have little influence on wheel/rail contact stress. In the forepart of this region, wheel/switch rail lateral wear is more serious, so a appropriate slope on wheel tread must be required as soon as possible to ensure passing curve successfully. Then more serious wear would not happen on general condition.
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