This article delivers useful practical contemplation of stray current calculation and monitoring endeavors in dc mass-transit systems. We focus on interpreting stray current calculations-carried out at the design stage for real-life conditions-and on determining safety margins to cope with calculations following oversimplifying assumptions. We also discuss the general specifications and benefits of the direct stray current monitoring method, through addressing the implications that arise from implementing the alternative rail potential monitoring method informatively quoted in European (EN) Standards.