A way cover section is shaped with a continuous lateral arc by pre-stressing so that its top panel has a radius in its top panel from one side panel of the cover section to the other. A wiper at the leading edge of the cover sections that may also serve as a bumper. The wiper has an elastomeric wiper section at one end and an elastomeric bumper section at the other end, with an intermediate section of a harder and more lubricious material that fits on a rolled over edge of the cover section to which the wiper is attached.

A multi-sided bellows cover has panel sections formed of extruded plastic panels that are connected end-to-end by bead-in-slot connections. The panel sections can be made of one or more rigid wall sections that are connected at the fold lines by flexible web sections or by the bead-in-slot connection. The panel sections are integrally molded by extrusion, and many serial wall sections alternating with web sections may be integrally co-extruded with one another.