I happened to be in Sweden on September 3rd, 1967 to witness a day unlike any other. It was "Dagen H," or "Höger Day," the day on which Swedish road traffic switched from driving on the left to driving on the right. I had witnessed the razzmatazz leading up to it, the campaign to raise public awareness and to prepare people for the changeover. The Dagen H logos were everywhere, on cakes in shop windows, baked in its hexagon shape, iced in black with yellow edges, and with a yellow H in the middle. The other logo, the blue and white one showing a white arrow switching from left to right, appeared on milk cartons and even underwear. There was a TV contest for the best song about it.

Why did they do it? It was because their Nordic neighbours such as Norway and Finland drove on the right, and because most Swedish cars were left-hand drive. On narrow Swedish roads it made it hard for drivers to see oncoming vehicles. It was not a popular move, however. A 1955 referendum had shown 83% opposed to a change, but the Swedish government decided it knew better and did it anyway, and the Swedes fell into line.

It was a massive project, involving replacement of 350,000 signs and repainting the lines on the roads. Each intersection had new poles erected, covered in black plastic until the big day. New road lines were painted in white, instead of the traditional yellow, then covered with black tape until the day of the change.

On Sunday September 3rd, all non-essential traffic was banned from 1.00am to 6.00am. Any vehicles that were on the roads had to stop at 4.50am, cautiously switch sides, then stop again to avoid colliding with others doing the same. Work crews laboured throughout the night removing covers from the new signs and covering up the old ones. The black tape on the roads was removed to reveal the new white lines.

An amusing sight greeted me the next morning. Cars were crawling along at 15mph with headlights blazing. Teenagers in uniform were stationed at intersections, directing traffic with huge flags, one yellow and one black. Everyone seemed very nervous, though there was much goodwill as people helped and directed each other.

It was costly. Apart from the infrastructure changes, over 1,000 new buses had to be bought with doors on the right-hand side, and 8,000 older buses were modified to have doors on both sides. Trams in Sweden's major cities had to be withdrawn and replaced by buses. Was the cost justified? The answer appears to be no in terms of traffic accidents. While there was an initial fall of 40% in motor insurance claims as everyone drove more cautiously, it did not last. Over the next 6 weeks the accident levels rose to the previous levels, and by 1969 they were back to where they were before.

If the aim was to make Swedish driving more in harmony with the rest of the world, it had limited effect. It aligned them with most of Europe and the USA, and Iceland, which did the switch 8 months later, but left many nations still driving on the left, including major ones like India, Japan and Australia, and of course the UK, plus many Asian and African ones. Former colonies that still drive on the left include Kenya, South Africa, Zimbabwe, Lesotho, Botswana, Malawi, Zambia, Namibia, Swaziland, Uganda, and Tanzania, Mozambique and Mauritius. In Asia they include Singapore, Pakistan, Indonesia and Sri Lanka, and Thailand that was never colonized.

The lines of Robert Southey's "After Blenheim" spring to mind.

"But what good came of it at last?" Quoth little Peterkin.

"Why that I cannot tell," said he, "But 'twas a famous victory."

It took a huge commitment for 4 years, unprecedented manpower and resources, and it caused major dislocations. Yet if Sweden had not done it, it is doubtful if it would have been adversely affected. It's what government planning and projects often do.

There's an epilogue of sorts. I was in Sweden at the time of the 2003 referendum on whether they should join the euro. I was invited there to help the "Nej" campaign. Despite the support of virtually all parties and the media, it went down pretty well everywhere except Stockholm County. It was non-binding, but this time the Swedish government chose not to override their electors. Of course, the EU may yet compel them to do so at some stage…