fa عمومى General پژوهشي Research The flange climb derailment is one of the cause of derailment for a typical switch. The derail<a aria-haspopup="false" aria-labelledby="cke_138_label" id="cke_138" role="button" tabindex="-1" title="Insert Page Break for Printing"><span style="background-image:url(http://ijrare.iust.ac.ir/ckedit/plugins/icons.png?t=DBAA);background-position:0 -1488px;background-size:auto;">&nbsp;</span><span aria-hidden="false" id="cke_138_label">Insert Page Break for Printing</span></a>ment for the switch is a complex phenomenon since the contact area is changing dynamically. The contact angle between the wheel flange and the switch point is investegated in terms of the risk on the derailment. The contribution of this study is proving that UIC716R standard recommendation about the switch flange geometry is valid in terms preventing the derailment. Switch, Derailment, Contact angle 33 39 http://ijrare.iust.ac.ir/browse.php?a_code=A-10-25-24&slc_lang=fa&sid=1 Veysel Arlı arli@istanbul-ulasim.com.tr 180031947532846001572 180031947532846001572 Yes Consultant of the General Manager Istanbul Ulaşım A.Ş. Istanbul, Turkey Consultant of the General Manager Istanbul Ulaşım A.Ş. Istanbul, Turkey Haydar Sahin 180031947532846001573 180031947532846001573 No System Integration Department Istanbul Ulaşım A.Ş. Istanbul, Turkey System Integration Department Istanbul Ulaşım A.Ş. Istanbul, Turkey Fatih Zafer Topsaka 180031947532846001574 180031947532846001574 No System Integration Department Istanbul Ulaşım A.Ş.Istanbul, Turkey System Integration Department Istanbul Ulaşım A.Ş.Istanbul, Turkey Kazım Can 180031947532846001575 180031947532846001575 No R&D Manager Istanbul Ulaşım A.Ş. Istanbul, Turkey R&D Manager Istanbul Ulaşım A.Ş. Istanbul, Turkey