This study proposes the design and analysis of nomographs for minimum headway calculations using critical blocks to reduce the complexity of mathematical equations. For trains with different speeds, block overlapping should be checked forward or backward in a looping manner, while nomographs simplify the analysis and eliminate iterations. Nomographs for headway calculation are constructed using Python scripts in PyNomo software. The associated variables include train speed, train length, and block length. Three nomographs are designed for three types of operation: Model 1 for cases wherein two trains have equal speeds, Model 2 for those wherein the leading train is faster, and Model 3 for those wherein the leading train is slower. The validation reveals that the nomographs yield minimum headways that are close to the result obtained by mathematical derivation. Data can be used to create a train schedule for safe operation without conflict.
