ou may have noticed that your car journey to work has got a lot worse this week. The start of the new term sees 20 per cent of the vehicles around you back on the school run. And in the past 10 years the proportion of students joining that run has almost doubled - a million extra every day.
Even worse, their rush-hour journeys are getting longer - up 45 per cent to an average 3.3 miles for secondary school children and a third to 1.5 miles for primary school children.
But if you think these car journeys are a pain for you, that's nothing compared with the problems we are storing up for the children involved.
We are bringing up a generation of couch potatoes protected from the real world and too unfit for many jobs and sports. As one academic put it, we are a nation of battery-reared children rather than free-range ones.
We might scoff at American levels of obesity but in the 10 years to the mid-1990s, the number of overweight boys in England nearly doubled to 9 per cent while the percentage of fat girls went up to 13 per cent (16 per cent in Scotland).
And just as the waistbands grew, so the exercise went down. In almost the same period about 400,000 fewer children walked to school. Meanwhile the numbers cycling fell from 300,000 to 100,000.
The school run is impairing children's health, reducing their independence and the opportunity to mix with their peers and to acquire skills like reading bus timetables and maps.
Parents driving their children to school are a major cause of accidents. Double and triple parking outside the school gates cuts visibility and causes confusion. Many teachers are in despair at the insensitivity of parents, many of whom could cut out four car trips a day by looking at alternative and better journey choices.
But it is perfectly feasible to cut both morning traffic and child obesity.
In America, for example, 54 per cent of under-12-year-olds go to school on the traditional yellow school bus. Here, just 9 per cent of children under 11 make the journey by bus.
In Denmark 40 per cent of children cycle to school. Their peer group think they are sissies if they are driven there by their parents.
The UK will be running the first commercial pilot yellow school bus projects in the New Year. Buses will offer the complete American package with near door-to-door service, same driver each day, same seats daily, a passenger checklist and radio contact with an operations room.
US levels of take-up would dramatically reduce morning traffic here while still giving parents confidence in their child's safety. And in the US children value the extra time they spend with their friends rather than being stuck in the family car.
There are plenty of other schemes being rolled out across the country by local authorities and their new school transport officers. Bright ideas include the walking bus where children are collected from their door and walk hand-in-hand to school under a parent's supervision, and cycle and walking priorities geared to known school routes.
In the Netherlands three-quarters of all children either walk or cycle to school, and proportionately fewer children are killed walking or cycling than here (1.07 per 100,000 compared with 1.17).
Sceptics might say this is because of the critical mass that they have achieved across the country, but at Kesgrave school, near Ipswich, 80 per cent of children - around 800 - now cycle to school and accident figures have gone down.
The new Government and police focus on unacceptable speeding can only help.
In Denmark, where child pedestrian casualties were once the worst in Europe, older children are encouraged to act as informal crossing patrols for younger students. And a similar scheme to the UK Safe Routes to School cut casualties by 80 per cent in some areas.
Our child pedestrian death rate is one of the worst in Europe - nearly four times that of Sweden and significantly higher than France and Germany at a rate of 0.87 per 100,000 children.
The opportunities are there for change, but we have all got to play our part.
Professor David Begg is chair of the Commission for Integrated Transport, set up by John Prescott in April 1999