二、特种道岔 现场铺设数量较多的特种道岔是交叉渡线、交分道岔和对称道岔。特种道岔构造复杂、零件繁多,造成了养护维修工作的困难,特别是这些道岔多铺设在峰下线路和车站咽喉区。车流密度大,线路残余变形积累快,零部件容易松动和损坏,是车站线路突出的薄弱环 Second, the special turnout laying a large number of special on-site turnout is cross-over, turnout turnout and symmetrical turnout. Special turnout complex structure, many parts, resulting in the maintenance of maintenance difficulties, especially in the laying of the turnout under the peak line and the station throat area. High traffic density, rapid accumulation of residual deformation lines, parts easily loose and damaged, is the station line prominent weak ring