Colour coding is required on OHE masts with special features (rail marking, implantation, etc.). Since many different marking methods were historically followed across Zonal Railways, a standardised colour-coding scheme was proposed — referencing ACTM (Manual of AC Traction Maintenance and Operation) provisions where applicable, so railways can adopt a UNIFORM scheme for easy identification by TrD staff.
Six Core Safety Principles (Stated Upfront)
- Plan every job.
- Use the right tools for the job.
- Isolate the equipment.
- Minimize the hazard.
- Protect the personnel.
- Assess abilities of the personnel — and EDUCATE for these principles FREQUENTLY.
The 15 Standardized Colour Codes
| # | Feature | Colour / Marking | Height from Rail Level |
|---|---|---|---|
| 1 | Leaning of Mast (ACTM Vol.II Part-I, Para 20305, Pg.60) | Yellow paint band, 50mm width (stencil) | 1.85 m |
| 2 | One Mast Holding Two Elementary Sections | Yellow base + 10 red zebra bands (50mm width, 30° incline, 20mm spacing); caution board reading 'BEFORE CLIMBING ON MAST/UPRIGHT, TAKE POWER BLOCK ON BOTH ELEMENTARY SECTIONS' both sides above number plate | Below the mast number plate |
| 3 | Identification of Isolator for ASM | Blue band, 50mm width | Just below the isolator handle |
| 4 | Excessive Contact Wire Wear (ACTM Vol.II Part-I, Para 20309, Pg.64) | Black band, 75mm width | 1.00 m to 1.25 m |
| 5 | Critical Implantation | Black base + 10 yellow zebra bands (50mm width, 30° incline, 20mm spacing) | 0.40 m to 1.00 m |
| 6 | Rail Level (ACTM Vol.II Part-I, Para 20306, Pg.62) | Yellow band, 50mm width; 'ERL' lettering in black, 25mm font (Times New Roman), 5mm letter thickness; black line, 5mm thickness | — |
| 7 | Setting Distance / Implantation (ACTM Vol.II Part-I, Para 20306, Pg.62) | Yellow band, 50mm width; black lettering (e.g. 'IMP 2.50 m'), correct to 2 decimal places, 25mm font, 5mm thickness | 0.20 m to 0.40 m |
| 8 | Telephone Socket Direction | Yellow band, 100mm width; black stencilled arrow indicating direction, within 100mm | 1.25 m to 1.50 m |
| 9 | Kilometer & Location Number on Mast Web (opposite number plate / direction of traffic) | Yellow paint on web; lettering 100mm width, 10mm thickness | 1.25 m to 1.50 m |
| 10 | OHE Tension Length on ATD Mast (half tension length) | Yellow band, 100mm width; black lettering (e.g. 'TL 750 m'), correct to 2 decimal places, 25mm font, 5mm thickness | As per site condition |
| 11 | ATD Lower & Highest Temperature Marking (ACTM Vol.II Part-I, Para 20316, Pg.70) | Yellow band, 100mm width; BLACK band, 20mm thickness | As per site condition (separately for highest and lowest) |
| 12 | ATD Ambient Temperature (35°C) Marking (ACTM Vol.II Part-I, Para 20316, Pg.70) | Yellow band, 100mm width; RED band, 20mm thickness | As per site condition |
| 13 | Kilometer & Mast Number on Bottom Two Counterweights of ATD | Yellow paint on bottom two counterweights; black lettering, 120mm width, 10mm thickness | — |
| 14a | Headroom Height of ROB from Rail — minimum 6.25m | Caution board 'OHE HEIGHT CRITICAL TRACK NOT TO BE LIFTED/RAISED' on pillar/support/column of ROB | Not less than 3.00 m |
| 14b | Headroom Height of FOB from Rail — minimum 5.87m | Same caution board, on BOTH pillars/supports/columns of FOB | Not less than 3.00 m |
Exam Focus — The Zebra-Band Pair: Red vs Yellow Distinguishes the Hazard Type
Two codes use a zebra-band pattern (10 bands, 50mm width, 30° incline, 20mm spacing) but differ in colour and meaning: RED zebra bands on a yellow base = 'one mast holding two elementary sections' (an electrical-isolation hazard — you could power-block one section and still be standing next to a live one). YELLOW zebra bands on a black base = 'critical implantation' (a structural/clearance hazard). Both patterns look visually similar at a glance — the base colour (yellow vs black) is the fast way to tell them apart, not the band colour alone.
Exam Focus — The Height-Band Ladder (Rail Level Upward)
Reading the mast bottom-to-top gives a clean sequence worth memorizing as a ladder: 0.20-0.40m = Setting Distance/Implantation → 0.40-1.00m = Critical Implantation zebra band → 1.00-1.25m = Excessive Contact Wire Wear → 1.25-1.50m = both Telephone Socket Direction AND Kilometer/Location Number (these two share the same height band, distinguished by content, not position) → 1.85m = Mast Leaning band. This ladder is a strong way to recall which marking sits where, rather than memorizing 15 heights independently.
Exam Focus — ROB vs FOB Headroom Heights
A precise, easy-to-test pair: minimum ROB (Road Over Bridge) headroom from rail = 6.25m; minimum FOB (Foot Over Bridge) headroom from rail = 5.87m — ROB needs MORE clearance than FOB (road vehicles are generally taller/more variable than pedestrian traffic loads). Both share the same caution-board wording and the same 'not less than 3.00m' height rule for where the caution board itself is mounted — but FOB requires the board on BOTH pillars while only one location context is specified for ROB.