Klaus Kirsch was a main board director of Keller Group plc, responsible for operations in Continental Europe and overseas until his retirement in 2001, and served thereafter as adviser for the Group's technical development. He has been involved with some fundamental breakthroughs in foundation engineering, notably the introduction of the vibro stone column technology in the United States, and was instrumental in the development of a new generation of depth vibrators. He has authored many papers and a book on vibratory deep compaction.

Alan Bell is a technical consultant to the Keller Group plc. He was managing director of Keller in the United Kingdom until 2009 and has had close involvement in ground improvement techniques and their development at both the national and international level for over 30 years, including the introduction of vibrated concrete columns to the United Kingdom. He has contributed to many technical publications and is a visiting professor at the University of Strathclyde in Glasgow.