A system provides pneumatic conveyance of granular materials, for example, grain or other dry, loose commodities. The retention clip may engage the glazing panels at locations lower than top ends of the upstanding seam flanges. When a movement direction at this time is the same as a movement direction intended by the driver, the braking force is decreased to zero for smooth starting. For example, various alternative routing plans may be registered with the packet network and stored in a database. When there is a blockage, an alarm can be sounded.