A barrier member comprising: a support; a first engagement member coupled to the support; and a translatable column defining a longitudinal axis, wherein the translatable column is rotatably and translatably mounted relative to the support, wherein the translatable column is translatable between: a first position in which the translatable column and the first engagement member are spaced apart from one another such that the translatable column is rotatable about said longitudinal axis; and a second position in which the translatable column and the first engagement member are engaged to prevent rotation of the translatable column about said longitudinal axis.