With the evolution of internet technology, it has become possible to create public participation over the internet. This project proposes a public participation GIS system, to handle the public participation issues regarding a suggested light rail solution following “Ring 3” west of Copenhagen. The solution is based on open source software, and uses the possibilities form Google maps as data background, making it expandable and free to use for any case. Through the development of the application it became clear, that in order to create a successful solution, several key elements was required. The solution had to be user friendly, to enable the broad public to participate, but also had to offer advanced functions for the trained users. Furthermore the solution had to be technologically secure, to avoid unintended use of the system.