A waterproof expansion joint comprises a ballast protection plate and at least one locating device configured to retain the ballast protection plate over a deck joint. A flexible sealing member located below the ballast protection plate can include at least one flange portion and at least one expansion feature. Each expansion feature can include a shape preformed into the flexible sealing member extending downward into the deck joint and configured to deflect, enabling variation in the width of the flexible sealing member to match the width of the deck joint.