Almost a third of children are now taken to primary school by car, because parents think it is too dangerous to let them walk or cycle, according to new figures from the traffic and transport institute.
The shift towards car trips comes despite the fact most children live close to their schools.
Fewer than one in five primary school children now go to school alone, the institute says. It bases its claims on research at 180 different primary schools.
Ten and 25 years ago, around one in four children under the age of 12 or 13 were taken to school by car.
The institute says it is unable to explain the increase because accident rates do not indicate the roads are more dangerous.
Over the past 10 years the number of young children killed in traffic accidents has gone down sharply, even though the roads are busier.