Disclosed is a rail supporting assembly for supporting a contact rail of a railway system that includes a base, a rail support head positioned relative to the base, and a support member comprising a dielectric phenolic material coupled to and positioned between the rail support head and the base to thereby support and insulate the contact rail. The support member includes a fracture area to facilitate fracturing of a sidewall of the support member when a fracturing force, such as a electrical arc event, is applied to the support member. The support member preferably is coated with a varnish to prevent absorption of water by the support member.