In order to create punctual timetables, it is necessary to accurately calculate and plan out many values, such as running time between stopping or passing points, headway between trains, train scheduling, rolling stock scheduling, driver and crew scheduling, operation scheduling in stations and depots and capacity of the line / infrastructure. Among these values, shortest running time between stopping or passing points must be calculated first, as this is the basis of timetabling. This document describes a practical procedure to create and verify speed-distance diagrams and its speed curves using the parameters specified in ISO 24675-1. Shortest running time is obtained by numerically integrating the speed curves. This enables railway infrastructure managers, railway operators and related organizations to calculate accurate running time at the stage of setting up feasible and punctual daily timetables, seasonal timetables, annual timetables, strategic timetables for long-term perspective, and other timetables of a railway system. This document excludes running time calculation used for purposes other than timetabling.