||Uncertainties and the dynamic nature of on-site activities require complex coordination of information, resources and tasks. Problems caused by unanticipated events must be solved concurrently and should avoid project delays and costs increasing. For effective solving of such problems, the immediate availability of information and a prompt response of project participants on various levels of project organization are crucial. A combination of both conditions facilitate the optimum decision-making in cases of unanticipated events. Based on experiences from a series of experimental projects called E-site, it is our strong belief that a large amount of potentials for on-site problem solving lies in the knowledge, experience and capability of the site staff themself. Therefore, there is also a need to effectively link together the rich knowledge and experience of site staff and include site staff into problem solving processes. This paper describes a human oriented on-site problem solving system supported with context-aware communication to help dealing with unanticipated events on construction sites.