Railway noise is a very important and growing health hazard in today´s society.Railway systems pass through towns and cities and create noise. When trainsride through or over railway bridges, switches and crossings the noise increasessubstantially, causing great annoyance to the residents in the area.At the present time, acoustic regulations exist in most countries and are set to achievea good environmental quality in residential areas, schools, hospitals, offices andhotels.A few calculation models exist for railway traffic noise, such as The NPM 1996,NORD2000 and Cnossos-EU. The NPM 1996 is currently used in Sweden to calculatenoise propagation from railway traffic. To uphold the regulations set, it is importantthat the method used is as precise as possible. All of these calculation modelsare based on several correction factors. Today, the current corrections for trackconditions, that is railway bridges, switches and crossings, are not very accurate andneed to be reconsidered.The aim of this project was to investigate and quantify the error of the NPM correctionfactors and give some indication of how they should be adjusted. This is done to makethe noise prediction from railway traffic more accurate and thus protect the residentsfrom these health risks.The specific objective was to perform significant amount of field measurements ofnoise from trains on different steel bridges, switches and crossings, as well as on afew concrete bridge according to the measurement standard Nordtest NT 098. Thefield work was carried out over the period March to May, when weather conditionsmet the criteria for field measurements, in and around the Stockholm area.The results obtained revealed that the correction factors for steel bridges andcrossings are considerably lower in the NPM than measured in this project. However,the correction factors for switches and concrete bridges are similar to the ones inthe NPM. In this thesis, a part of the correction factors have only been invalidatedto a degree. It has been shown that each bridge is unique and perhaps there is apossibility of finding similarities between some type of bridges. However, much moreiv |measurements are needed to see any correlation between each bridge type. Thus,further and more comprehensive measurements have to be carried out in order toestablish new accurate correction factors for track conditions in the Nordic PredictionMethod.