The complexity and severity of contact stresses at the rail-wheel interface coupled with operational conditions of acceleration and braking can lead to the formation of discrete defects such as squats and wheel burns even in the best maintained railway networks. Modern track inspection technologies are deployed for the early detection of such defects to manage the required remedial action to prevent transverse rail breaks. The remedial actions involve either in-situ repair or the replacement of a short length of rail containing the defect. This paper examines the technical and financial imperatives for rail defect repair and details a novel, cost effective, and largely automated low preheat weld restoration technology for the in-situ repair of discrete rail head defects. The paper provides explanation of the science behind the use of low preheat process through instrumented trials to establish the thermal history, metallographic examinations to establish internal integrity, and controlled tests to demonstrate fatigue resistance under cyclic loading. Key findings of the independently audited trial are also summarised.