ɪn ɹˈeɪl tɹˈænspoːɹt, ɡˈɑːɹd ɹˈeɪlz ɔːɹ tʃˈɛk ɹˈeɪlz ɑːɹ ɹˈeɪlz jˈuːzd ɪnðə kənstɹˈʌkʃən ʌvðə tɹˈæk, plˈeɪst pˈæɹəlˌɛl tə ɹˈɛɡjʊlɚ ɹˈʌnɪŋ ɹˈeɪl tə kˈiːp ðə wˈiːlz ʌv ɹˈoʊlɪŋ stˈɑːk ɪn ɐlˈaɪnmənt tə pɹɪvˈɛnt dᵻɹˈeɪlmənt.
In rail transport, guard rails or check rails are rails used in the construction of the track, placed parallel to regular running rail to keep the wheels of rolling stock in alignment to prevent derailment.