A method to calculate the network-wide costs of realizing di!erent noise control possibilities and their bene"ts in terms of noise reduction for lineside inhabitants has been implemented in Switzerland. These studies have shown that an optimal cost distribution consists of spending 65% of the available "nances on rolling stock improvement, 30% on noise control barriers and 5% on insulated windows. This mix protects 70% of the lineside population for 30% of the cost necessary to attain threshold levels for all inhabitants. This noise control strategy has been accepted by the federal tra$c and environment agencies involved and will save billions of Swiss francs. The success of the calculation methodology has prompted development of a Europe-wide decision support system to the same e!ect. Along two freight freeways the relationship between rolling stock improvement, noise barriers, insulated windows, operational measures and track characteristics is being studied. The decision support system will allow determination of those combinations with the best cost}bene"t ratios. The study is currently being undertaken as a joint venture by the railways of Switzerland, France, Germany and the Netherlands as well as the European Rail Research Institute. The results constitute part of the negotiating strategy of the railways with European and national legislators.