Railways & Metro

IEC 61537 defines load classes (A through E) based on the Uniformly Distributed Load (UDL) the tray carries at a given span with deflection not exceeding L/100. The maximum span depends on the tray cross-section, gauge, and cable load, not a fixed number. For a standard 300 mm wide, 1.5 mm gauge ladder tray at a 3,000 mm span: rated at approximately 85 kg/m UDL (Class B). In practice: light loading (control cables, fill <40%) supports 3,000 mm spans; heavy power cable runs (35 mm² and above) typically require 1,500–2,000 mm spans to stay within Class C or D ratings. Vertical runs: halve the horizontal rated span. At bends and fittings: add a support within 300 mm either side. The span table from the tray manufacturer is authoritative, never use a rule-of-thumb without checking the actual UDL against the rated span.

Indian Railways and metro authority specifications (RDSO, Delhi Metro Rail Corporation, L&T, Alstom sub-contracts) universally require hot-dip galvanized (HDG) finish to IS 4759 for all external and exposed cable trays in electrification, signalling and OHE (overhead electrification) installations. The aggressive combination of train-generated particulate, humidity and intermittent chloride (coastal metros) rules out pre-galvanized and powder-coat as standalone finishes for outdoor applications. HDG provides 25–40 year service life with no maintenance requirement and meets the RDSO standard for cathodic protection compatibility. For indoor depot and station rooms, pre-galvanized perforated trays are accepted. Material test certificates (IS 4759 coating compliance) and dimensional inspection reports are required documentation for all RDSO-registered vendor submissions.

Metro station platforms and maintenance access walkways in India follow IS 2713 (electroforged gratings) as the primary standard, with DMRC and most state metro authorities also referencing BS 4592 for cross-checking load class and deflection. Heel-safe is mandatory on all passenger access areas: the maximum opening dimension is 35×35 mm, achieved by specifying a 50 mm or 40 mm cross-bar pitch. Load class for platform edge and maintenance walkways: minimum 4.5 kN/m² UDL (Class W / pedestrian loading per IS 2713). For maintenance vehicle access within depots, 15–28 kN/m² (forklift-rated sections) are required. Surface finish: hot-dip galvanized IS 4759 for external and exposed areas; natural mill finish with anti-slip nosing strips for indoor depot platforms. Vajra supplies electroforged grating panels cut to size with swaged end flats and recessed fixings for platform applications.

Vajra International is a direct manufacturer of industrial electrical, structural, and precision metal systems, cable trays, earthing and grounding, copper busbars, electroforged gratings, fabricated steel and towers, solar mounting structures, and CNC machined and sheet-metal components, across mild steel, stainless steel, aluminium and copper.

A direct manufacturer. All production runs under single-facility control across three production units, with no intermediaries, which removes trading-house markups and gives full control over quality, finish and delivery.