This paper discusses the facilitation of worldwide concurrent design within the domains involved in environmental planning, urban design and civil engineering. Typical projects in these domains require the collaboration of many experts. Each of these has his reference framework for the taskat hand and for the variables used. The amount of variables makes it impossible for each project participant to take account for all possible impacts of proposed or planned actions. The typical project demands for a concurrent design process that enables all participants to concentrate ontheir domain of expertise. On the other hand the design process should enable them to have insight in the problems, within the domains of other experts. The system should provide a generic environment with the ability to attach domain specific knowledge. By providing this support thesystem integrates knowledge specific to various expert domains.In the PortPlan project within the LWI organization a system is being developed that supports the integration of various reference frameworks involved in environmental planning. We no longer need to develop a common language for the users. The system contains a dynamic set of scalebound reference objects for the domains involved. The system facilitates the communication of object characteristics. It also supports the presentation of these objects, in legends for each participant involved.We achieve the communication between participants using a dynamic legend. We also enable all participants to become informed on the interests of other participants. We achieve the technical communication using the exchange of interventions. We do not exchange results. This leads to alow "network traffic load" and thus enables the system to operate within the current Internet infrastructure. In this paper we present the problem area of concurrent design in environmental planning. We present this describing the background of our project, describing the overall architecture of the system and presenting the first findings of user studies.