This part of EN 15437 defines the minimum characteristics for the interface between a trackside Hot Axlebox Detector (HABD) and Rolling Stock (RST) that comply with the European Directives for Interoperability to ensure that the minimum functional requirement of the interface is achieved. The minimum requirements of the interface apply to: a) Rolling stock conforming to standard European railway gauge, that is 1 435 mm; b) Rolling stock axles fitted with outboard bearings; NOTE 1 The design of rolling stock axles fitted with inboard bearings should respect the requirements set out in Note 2 of 5.2. c) Rolling stock with a maximum design speed lower than 250 km/h; NOTE 2 Interoperable rolling stock with a maximum design speed higher than or equal to 250 km/h are mandated to have on-board equipment for axlebox condition monitoring. The requirements for on-board equipment are described in !EN 15437-2:2012+A1:2022. NOTE 3 Interoperable rolling stock with a maximum design speed higher than or equal to 250 km/h are outside the scope of this Part of the standard. However, if such rolling stock are required to be monitored by HABDs their target area should comply with the requirements specified in this standard, except where stated otherwise. d) Trackside HABDs that are required to monitor rolling stock with a maximum design speed higher than or equal to 250 km/h. The rolling stock requirements of the interface are described in Clause 5 and for the HABD requirements of the interface are described in Clause 6. The scope of this part (part 1) of the standard does not include: - Hot Wheel (Hot Disc) Detectors (HWDs). However, HWD are often installed in combination with trackside HABD to provide a dual monitoring system. This standard does not prevent the use of such a combination; - how a HABD measures the temperature and identifies axle box position. This is part of an individual equipment design and not part of the functional requirements of this standard; - operational requirements for acting on the information reported by the HABD system; - maintenance requirements for HABD systems.