What major functional improvement did Robert Gray's wheelie bin primarily address over Poubelle's era bins?

Eliminating the need for manual lifting by workers

The transition from the heavy, fixed-position metal bins of the Poubelle standard to Robert Gray's wheelie bin represented a fundamental shift in logistics centered on labor efficiency. While Poubelle's innovation organized containment, it still required sanitation workers to manually lift and physically tip each heavy container into collection carts, a laborious and demanding task. Gray’s design, utilizing wheels and a specific lifting bar catch, was engineered so that the container could be lifted and emptied mechanically by the truck apparatus. This innovation directly eliminated the heavy manual lifting requirement, drastically improving efficiency and worker ergonomics for modern curbside collection services.