In the beginning of 2004 The Danish Road Institute/Road Directorate (DRI) and Road and Hydraulic Engineering Institute in the Netherlands (DWW) made an agreement to cooperate on the DRI-DWW noise abatement programme in the period 2004-2007. A total of 7 research and development projects will be carried out inside the framework of this programme. The DRI-DWW noise abatement programme is a part of the Dutch IPG programme on development and testing of noise reducing measures for road traffic. One of these projects is the Thin Layer Pavements Project. The main goal of the joint projects is to develop and test noise reducing thin open layers with an optimized noise reducing capacity. The project is divided in an exploration phase and a research and implementation phase. An important part of the first phase is a literature study on the existing international knowledge in the field of thin layers and noise reduction. The study includes an inventory of existing suitable thin road sections for further research. This note is the result of the literature study and Milestone M2 of the Thin Layer Pavements Project. In the annexes the results from meetings held with American experts in March 2005 are presented.