To me it had to be minimal yardage, because we had to pay for every bit of it. On the other hand, access to every premise had to be as perfect as it could possibly be. And there had to be a minimum number of conflict points on the whole system.
I came to the conclusion that number one danger areas were crossroads. Number two danger areas were T-junctions, and if you could minimise those, you had gained an enormous amount. We then started looking at our own work, and as we went on, we decided that roundabouts were preferable to crossroads. And so we built a roundabout. We were then able to measure the performance of a roundabout against some traffic signals which because this was the Great North Road throughout the first twelve, thirteen, fifteen years of our history, the Ministry of Transport insisted on having traffic signals at Six Hills Way crossing of the Great North Road.
And so we had this forced on us, this traffic signal against my advice and against my better judgment. But I understood; I knew what the Ministry of Transport trousers felt like, and so, but it gave me an opportunity which was unparalleled. I was able to watch that junction and I was able to watch my first roundabout junction, which was alongside it, the next road along. And we discovered that even with light traffic, we were getting six times as many accidents on the traffic signals as on the other one. And when we had more roundabouts, it never got worse than that. Sigma roundabouts were only creating one-sixth as many accidents as the traffic signals were.
And so we then decided that this traffic signal set would go as soon as the motorway took the trunk road from there to there. The county who were highway authority for it said, “Yes, we accept your argument”. And so immediately the traffic moved over, we created a roundabout there.