Rydym wedi gweld bod y tagfeydd ar yr M4 yn broblem oriau brig yn bennaf, yn gysylltiedig â chymudo.  Ychydig o ddewisiadau credadwy sydd gan bobl o ran trafnidiaeth gyhoeddus am y mathau o siwrneau y mae angen iddynt eu gwneud.
We have found that congestion on the M4 is largely a peak-hours problem, predominantly associated with commuting. People have few credible public transport alternatives for the types of journeys they need to make.