Diverging diamond interchange: an innovative way of managing traffic at a standard diamond interchange

A detailed traffic analysis of the KwaMashu Interchange on National Route 2 just north of Durban showed heavy congestion at selected approaches. The South African National Roads Agency Limited required short term, low cost capacity improvements at the interchange whilst long term improvements were being investigated and research in this regard was therefore undertaken. The interchange is a standard diamond interchange on a multi-lane national freeway and the ldouble-cross-overr and ldiverging-diamondr layouts which have been implemented in France for some time and have recently gained popularity in America were two such layouts that were identified as being potential low cost candidates to improve capacity at this interchange based on the geometric layout of the interchange and prevailing traffic characteristics. The design of the conversion of the KwaMashu interchange from a standard diamond to a diverging diamond layout is complete and construction of the conversion commenced in June 2012 and is due for completion in May 2013. This will be the very first diverging diamond interchange to be implemented in the Southern Hemisphere.