Nearly half of all 11 to 16-year-olds see bullying on the way to or from school, research has found.
Around 43% of those surveyed said they witness bullying on the school run but only half of those report it, a study by the Anti-Bullying Alliance (ABA) found.
The research, released at the beginning of national Anti-Bullying Week, found that 47% of those who witness bullying do not report it, with 50% of 13 to 16-year-olds failing to do so.
Of the young people who did not report bullying incidents, 44% said it is none of their business and 10% said they do not know who to tell.
ABA chairwoman Ross Hendry said: “This research shows us that a significant number of children and young people in England are suffering from bullying on their school journey.
“Whether they travel by bus, car, public transport, or if they walk to school we need to make sure they are protected.
“It’s of great concern that nearly half of young people who see others being bullied do not report it and that such a large proportion don’t think it’s any of their business to do so.
The report was released as Beatbullying, a separate anti-bullying charity, prepared to launch a “digital demonstration” in support of children’s rights.
More than 750,000 people, including Archbishop Desmond Tutu, have created virtual avatars that will “march” across around 60 partner websites against bullying.
A deputation of bullying victims and their families will meet Deputy Prime Minister Nick Clegg on Wednesday.