54. No street laid out or altered by the Kartripakkha shall be of less width than- (a) forty feet, if the street be intended for vehicular traffic, or (b) twenty feet, if the street be intended for pedestrian traffic only; Provided as follows:- (i) the width of an existing street need not be increased to the minimum required by this section, if the Kartripakkha consider it impracticable to do so; and(ii) nothing in this section shall be deemed to prevent the Kartripakkha from laying out service passages for sanitary purposes of any width less than twenty feet.