Railway applications - External visible and audible warning devices - Part 4: Audible warning devices for urban rail

This technical specification addresses safety requirements for auditory signaling equipment mounted on the exterior of urban rail vehicles. It focuses specifically on the performance criteria, sound pressure levels, and frequency characteristics necessary to ensure these signals are clearly audible to pedestrians and railway personnel in varying urban environments. The document establishes testing methodologies to verify the device's ability to transmit warning sounds under different ambient noise conditions, ensuring consistent performance across diverse operational scenarios. It outlines specifications for the signal's duration, modulation patterns, and directional radiation to minimize ambiguity during critical safety operations. Compliance with these technical parameters is essential for maintaining a safe operational environment where visual signals may be obscured or insufficient. The standard covers design constraints, installation guidelines, and maintenance intervals to guarantee long-term reliability of the auditory devices. By defining uniform technical benchmarks, it supports the interoperability of rail systems across different regions while enhancing overall public safety through improved warning clarity. This documentation serves as a foundational reference for manufacturers and operators in the urban rail transit sector, guiding the development and deployment of signaling systems that meet rigorous safety standards without referencing specific administrative origins or dates.