The rail way sector has been losing market, required increased subsidies and failed to generate anticipated rate of return. Therefore there has been a strong interest to measure the performance of railway operators in terms of punctuality. It is evident that In Norway punctuality shows considerable variation; most of the line being in non-optimal condition, speed is frequently reduced. Such speed reductions are often highlighted as major causes of delays. This master thesis studied the actual delays occurring on the parts of the line between Oslo and Trondheim which have speed restrictions. In doing actual time, travel times and speed restriction magnitudes data have been collected along the line. Combining both qualitative and quantitative approach to research the master thesis have mapped and analyzed speed restriction zones along the line. Using restriction mapping, statistical tools and curve fittings, the analysis revealed that as long as there is sufficient data, uniformity and regular fluctuation of the time magnitudes data there is an increasing effect caused and trend displayed on the actual time taken in the presence of the speed restrictions. Furthermore the research has looked in to the magnitude based relationship between the lost time due to restrictions and associated deviations in travel time. These resulted in a strong correlation between deviation of travel time and magnitude of lost time due to restrictions.