<p>Abutment and bridge designs include a bridge superstructure and abutment wherein the abutment has a vertical portion of a backwall that can be fixedly joined to the end face of the bridge superstructure without an interdisposed expansion joint. A downward facing surface of the bridge superstructure can be fixedly joined to an upward facing surface of the abutment, or alternatively, a bearing pad may be disposed therebetween. The abutment may further comprise a backwall made from a plurality of panels fixedly joined to a plurality of supporting piles. The abutments and bridge superstructure may be made substantially from composite materials including recycled structural composite and other thermoplastics.</p>