MY CHILDREN are sick only in their father's car. Only he has to contend with the vile smells that seem to seep into the upholstery and linger there. I just listen to the stories of bags that leaked and journeys that had to be stopped every 10 minutes. The reason is not some deep psychological trauma on their part; neither have I the power to cast a spell on them as they leave the door. No, it is much simpler than that. I go everywhere by train. But for how much longer?

I would like to pretend that my preference for train travel results from a deep sense of concern for the environment, but I am afraid it is entirely selfish. I am one of those people who can drive quite happily around Hyde Park corner during rush hour, yet I turn rigid with fear at the sight of three lanes stretching into the distance and lots of little metal boxes all travelling at breakneck speed.

I have heard all the statistics about motorway safety, but it still seems illogical to imagine that so many people can drive so fast, so close together, without colliding. I am constantly waiting for the sound of tearing metal, and after an hour of driving I am rigid with tension.

Early in June, the west of Scotland must be one of the closest places to heaven on earth. Purple rhododendrons mix with the never- ending green of the trees and patches of bright yellow where the flags are starting to bloom, while overhead the sky is an uncanny blue. I wouldn't miss this sight for anything, although it takes 12 hours' travelling to get there. Twelve hours that I would not even contemplate if I were obliged to drive.

Fortunately, an alternative is readily available. The InterCity journey to Glasgow takes five hours, and a fortunate connection allows us to pick up a train to Ardrossan Harbour. From there we make our way by ferry to Arran, then catch a local bus around the island. We arrive in time for tea at a little cafe overlooking the sea while we wait for another ferry to Kintyre, where friends are waiting to collect us.

On one occasion, friends we were travelling with were held up and we had to hitch the final stretch to the fishing village of Carradale and the stern grey house that is our base for a week of walking, wading in streams, riding horses across the wide and almost deserted beaches, and sampling the malts in the local pub.

I haven't always been such a wimp about motorway driving. In the two years after passing my test I whizzed up and down motorways with the best of them. Fear set in after an accident in France. Sanity and mobility were preserved because my partner handled the long- distance driving. Then, five years ago, I found myself alone, with two children, and broke. I was forced to contemplate an existence bordered by the M25, or face my panic. This time it was the Family Railcard that came to my rescue - a small scrap of cardboard, now costing pounds 20, that allows me to travel anywhere in the country for a discount on my own fare and a charge of pounds 1 return for each of my children.

With a card in my hand the world opened up. Visiting my brother in Milton Keynes (yes, I know it's only an hour up the motorway from London) became a journey I could contemplate without breaking out in a sweat, and the cost was no more than it would have been in petrol. A return trip to Ardrossan Harbour for the three of us costs pounds 53.05. Without a card, that same journey would cost pounds 138. My daughter can visit her best friend who has gone to live in Cardiff, and the two return fares to take and collect her will cost pounds 63.20 (provided I can drag my son along for the trip - a Family Railcard cannot be used by an adult travelling alone). Without the card, it would cost a prohibitive pounds 100 even if I left my son at home.

Fear of motorways pushed me on to the trains; but having discovered the wonders of the railway, I am now aware of the other benefits. Train travel often takes a little longer, but the compensating reduction in stress more than makes up for this.

I cannot imagine why people opt to drive with their children when they can train it in comfort with a table for colouring books and toys, and the chance to read or doze the journey away. Travel sickness, or a desperate need for a wee, walk, or snack can be coped with as the journey goes on. Nevertheless, I have learnt to carry a stash of fruit juice cartons to cope with that dreaded moment when British Rail announces that 'there will be no buffet on this train'.

All this and I haven't yet mentioned the benefits to the environment of not driving yet another car along Britain's overcrowded motorways. My preference for rail is good for everybody, yet the Family Railcard is the only concessionary card the Government is not committed to saving following the privatisation of British Rail. There has been no significant lobby calling for the retention of a concession that encourages families with children to travel by train.

The Family Railcard is by no means a social service. It has created new customers and earned a modest profit of pounds 7m a year. However, unless the Government changes its mind, new operators will have no obligation to keep this concession. They may well decide that the Family Railcard doesn't create enough profit to be worthwhile and may prefer to generate revenue with weekend special offers to holiday resorts, so that families go where the railways want them to.

Cheap day-trips to the seaside will be good for railway companies and for those families who would not otherwise get to the sea at all, but they won't allow families going to visit Aunt Martha to choose the train. If the choice is between buying full-fare tickets for four and taking the car, the car will win every time on cost grounds alone.

The Family Railcard keeps 250,000 potential car-using families off the roads for at least one journey a year. To let it go would make a mockery of transport planning. Its demise also would mean that people such as myself would have to bite the bullet and take to the motorways again. Do we really want terrified and reluctant drivers on the roads, slowing down the traffic, making erratic decisions and generally gumming up the works?