Most people associate roads with one colour: black. Traditional asphalt gets its familiar dark appearance largely from bitumen, the binder used to hold the aggregate within the material together. As the surface ages and is exposed to traffic and weather, it can gradually become lighter and greyer. But travel through…

Most people look at a road and see tarmac. There is a kerb at either side, perhaps a drainage gully nearby, road markings on top and a dark surface carrying thousands of vehicles. It is easy to assume that the visible asphalt represents most of the road construction. In reality,…

Roundabouts are designed to keep traffic moving efficiently, but from a road surfacing perspective they create a demanding environment. On a straight section of road, most vehicles travel forwards with relatively limited steering input. Their tyres predominantly apply vertical loads as they roll across the surface. A roundabout changes that…