"In 2004 an estimated 5 billion passenger journeys will be made in the UK, France and Germany and the market in the three countries is worth approximately €40 billion. [Ref. 1] . Based on the extrapolation of data relating to the UK, French and German railways [Ref 1], the 500,000 kms of rail [Ref. 2] on the European rail network has an average estimated 5000 rail breaks annually with about 1500 due to weld failure. Although the number of weld failures is relatively small compared to the estimated 11 million alumino-thermic welds on the European network, it still accounts for about 20% of the total 7000+ rail failures each year [Ref. 3]. There is no current available NDT method for the economic and reliable volumetric examination of alumino-thermic welds. This proposal describes the development of a rapid ultrasonic method for the safe and reliable NDT examination of the entire volume of in-situ alumino-thermic welds. The proposed ultrasonic system could be quickly deployed on track using a clamp-on device. The inspection scans will be carried out in a pre-determined sequence, and then the results compared with defect acceptance criteria that will be generated in the project. To achieve this objective, a rigorous analysis of the material properties, the defect interaction with the ultrasonic beams and the design of optimum scanning procedures will first be carried out. It is expected that the scans will be implemented by means of electronic scanning using novel phased arrays and multiple probes. The acceptance criteria will be generated by both Engineering Critical Assessment and fatigue tests on rail samples."