A Highways Agency article claims that their “Bag it and bin it” campaign has reduced motorway littering by 28%

This claim is based on the fact that the number of sacks of rubbish their contractors collect has fallen from 250,000 in 2011 to 180,000.

Another (more plausible?) explanation is that the same amount of rubbish is being discarded but less of it is being picked up.

Some of that extra accumulation is shown above on J15 of the M1.

Highways Agency article

Peter Silverman
17th April 2013