Two years ago this month, my beautiful granddaughter, Zenani, was killed in a road crash.

She had been a teenager for just two days when she was killed. My family suffered what no one should ever have to go through - the loss of a child.

My family will never recover.

When she left that morning for the World Cup kick-off concert in Soweto, I had no idea that it would be the last time I'd see her. I can't even remember if I said 'I love you' because we always used to say 'Love you lots, like jelly tots' to each other. I don't even remember how long I hugged her. You desperately reach for these memories and sometimes they fade away.

Yet there are reminders of Zenani every day in sounds, smells, tastes. One less child to send in the morning. One less uniform to buy. One less set of pencils. Sitting alone at the table is Zenani's younger brother. No one deserves his loss.

On the same day that Zenani was killed, 1000 families around the world lost a child in a road crash, their darkest fears realised. E very single day this is repeated again and again - 1000 more families who will never see their children grow up. What people don't realise is that this is preventable.

I must confess that, until it struck at the heart of my family, I was one of those who accepted road accidents as a terrible fact of life .

My family has long been associated with struggle. Our fight was for basic rights - the right to vote, the right to self-determination. Many people suffered greatly to achieve freedom in South Africa. But it is through suffering that you find the strength to take action.

So we are taking action. And when you start looking for solutions to this particular catastrophe, they are not hard to find. Road crashes don't require a new vaccine, or years of research to design a remedy. The framework and policies to protect our children and prevent these tragedies are already in place. They are simply not put into practice.

Children have no direct political voice. They are dependent on adults, on wider society, to keep them safe. They have a right to this protection, and we have a duty to provide it. This principle underpins the UN Convention on the Rights of the Child.

The convention , ratified by most countries and legally binding, is based on the understanding that children need "special safeguards and care". This includes the right to a "safe environment".

It is precisely at the point when children are closest to what is most likely to kill or disable them that the r ights of the c hild are neglected.

The greatest risk our children face is road traffic injury. Road injuries are the leading cause of death of children over the age of 10 worldwide. More than 300000 children and young people between the ages of 10 and 24 are killed on the world's roads each year and a million more are permanently disabled.

It is in Zenani's name that my family joins the Decade of Action for Road Safety.

It is a call for more to be done to protect children on roads around the world. The solutions are right in front of us. It may be a safe crossing to school, a footpath to keep our little ones safe from speeding traffic, making child helmets standard in countries in which the usual family transport is a motorbike; enforcing legislation on child-safety seats and seatbelts, and tougher action to prevent drunken driving and speeding.

Under the banner of the Zenani Mandela Campaign, more than a dozen organisations, including the Road Safety Fund, the UN Environment Programme and the World Resources Institute came together at the recent Rio+20 Conference in Brazil to pledge action and resources to protect children on the roads and improve urban road environments.

But more is needed.

The Zenani Campaign is an important part of Mandela Day, the day set aside by the UN to encourage people around the world to honour my father's birthday with actions to help others. It is an opportunity to commit ourselves to this new struggle so that other families do not have to go through our pain.

For the sake of thousands of young lives, we can, and we must, do far more.

• Zindzi and her daughter Zoleka Mandela are leading the Zenani Campaign: www. decadeofaction.org/zenani