Hamburg prescribes the use of a minimum 35% white aggregates in order to brighten road surfaces and to have a colder, deformation resistant road surface in summer. The high cost of these aggregate materials increased the incentive to recycle more than just base courses. A more careful consideration of the whole process of asphalt production was also triggered by recent dramatic increases in bitumen prices. The City allowed a group of private companies, who originally came up with the full recycling technology, to test its use on public roads owned by the City State. After the quality was then tested by Hamburg’s road construction authority, the City was reassured about the use of the 100% recycling process. Having renovated two other roads using this technique, a restricted tender procedure was conducted, with five companies invited to bid.

The process described in this example is considered to be very innovative and other German cities have already voiced interest in doing the same or have already built similar roads. In the future, the City of Hamburg intends to issue open tenders, rather than using restricted tenders for similar works. 

Photo by Mika Baumeister on Unsplash