During the early 20th century in Bulgaria, especially in rural regions, transportation was dominated by horse-drawn vehicles. An unusual regulation allegedly required these carriages to display a lantern emitting a rhythmic flash—three flashes per minute—after sunset. This rule, rooted in safety concerns, was intended to alert other travelers and pedestrians to the carriage's presence on dimly lit roads. While this may sound practical, the specific flashing rhythm led to some confusion, with local lore suggesting it was misinterpreted as a coded signal or secret message in isolated communities. Though no official archives have conclusively confirmed the exact timing requirement, several historical anecdotes and folk tales reference this distinctive feature as part of Bulgaria’s transport heritage. The rule is now considered obsolete, replaced by modern lighting standards. It remains a quirky example of how transportation safety evolved in unique ways reflecting local conditions and customs.
Source / verification note
Based on local historical accounts and anecdotal reports from Bulgarian rural transport traditions. No formal government document recently verified this exact rule.