A fluid impervious polymeric membrane separating a resilient pad from a railroad crosstie and having a width substantially greater than the resilient pad to resist moisture and mechanical forces in penetration between the concrete tie and the pad. The width is also sufficient to resist moisture penetration between the peripheral edges of the pad and the membrane. The width of the membrane is sufficient to extend essentially to the edge of the shoulder to limit lateral movement of the membrane caused by forces exerted by passing trains. Also, the membrane is substantially wider than the pad to extend essentially to the shoulder and insulator to resist lateral movement. Further, the pad is notched at a mid region adjacent to the insulator and clamp, with wider in regions, the notch resisting longitudinal movement of the membrane. The plastic material is selected from a group consisting of high density polyethylene, high molecular weight high density polyethylene and ultra high molecular weight polyethylene.