Audio Visual Alarm for Heavy Earth Moving Machinery (HEMM) – DGMS Guidelines, Safety Standards & MCQs

🧾 DETAILED NOTES

1️⃣ Introduction

In surface mining, Heavy Earth Moving Machinery (HEMM) such as dumpers, dozers, loaders, shovels, and graders operate continuously in close proximity to workers and light vehicles. Accidents due to collision, reversing, or poor visibility are common. To prevent such accidents, DGMS mandates installation of Audio-Visual Alarms (AVA) in all surface transport and earth-moving machinery. These alarms warn nearby workers and drivers of vehicle movement, especially during reversing, starting, or gear shifting.

2️⃣ DGMS Regulations & Circular References

Reference	Description
CMR 2017, Reg. 130 (2)	Machinery to be provided with effective warning devices.
DGMS Circular 8 of 2008	Safe design of haul roads & HEMM alarm provisions.
DGMS Circular 4 of 2010	Maintenance & inspection of safety alarms in HEMM.
DGMS Circular 2 of 2013	Fatigue monitoring and proximity warning systems.
DGMS Technical Circular 1 of 2018	Mandatory use of audio-visual alarms in all surface transport vehicles and dumpers.

3️⃣ Purpose of Audio-Visual Alarms

Prevent accidents due to reversing or starting of heavy vehicles.
Alert nearby workers through sound and flashing lights.
Enhance visibility and communication in noisy or dusty environments.
Comply with DGMS standards and ensure safe mine traffic operations.

4️⃣ Types of Alarms Used in Mines

Audible Alarms (Sound): Reverse horn, start-up siren, intermittent buzzer.
Visual Alarms (Light): Flashing beacons (red/amber), LED strobes on cab top.
Combination Systems: Synchronized audio and visual signals activated together.
Smart Warning Systems: Integrated with proximity sensors or radar-based alerts.

5️⃣ Technical Requirements (DGMS Standards)

Reverse alarm: Must be automatic on engaging reverse gear.
Audible range: Minimum 15 m in noisy conditions.
Flashing light: Visible from 100 m in all directions.
Color coding: Amber for moving, Red for reversing.
Dual system: Audio + Visual (mandatory).
Independent power backup (in case of battery failure).
Daily inspection by operator before use.

6️⃣ Inspection & Maintenance

Each vehicle must have a pre-start checklist confirming alarm operation.
Defective alarms must be tagged “Out of Service” until repaired.
Weekly inspection by mechanical engineer.
Monthly testing logbook to be maintained and countersigned by manager.
Failure to maintain alarm systems attracts DGMS violation under CMR Reg. 130 (2).

7️⃣ Case Study (DGMS Investigation 2016)

A fatal accident occurred when a dumper reversed over a helper near the loading face. Investigation revealed that the reverse alarm was non-functional and visual beacon was missing. DGMS directed immediate replacement of alarms and periodic testing before each shift, emphasizing compliance with DGMS Circular 1/2018.

⚙️ QUICK ONE-LINERS (Revision Points)

DGMS mandates Audio-Visual Alarms (AVA) in all HEMM.
CMR 2017, Reg. 130(2) – Machinery must have effective warning devices.
DGMS Circular 8/2008 – Haul road & equipment safety norms.
Reverse alarm must auto-activate in reverse gear.
Flashing light visible from 100 m distance.
Daily inspection of alarms mandatory before use.
Amber = Moving, Red = Reversing (color code).
Non-functional alarm = equipment out of service.
DGMS Circular 1/2018 – Compulsory AVA for all HEMM.
Enhances visibility, awareness, and accident prevention.

🧩 DESCRIPTIVE MODEL QUESTION

Q. Explain the DGMS requirements for installation and maintenance of Audio-Visual Alarms in surface transport and heavy earth moving machinery.

Answer:
As per CMR 2017, Reg. 130(2) and DGMS Circular 1 of 2018, all surface transport machinery and HEMM must be provided with functional Audio-Visual Alarms (AVA). These alarms give both sound and light warnings during reversing and movement to alert workers. They must have a minimum 15 m audible range and 100 m visual range. Reverse alarms should auto-activate with gear change, and defective systems must be repaired before operation. Daily pre-start checks and monthly logbook entries are mandatory to ensure compliance and prevent accidents.

🧮 25 DGMS-Based MCQs

Q1. Audio-Visual Alarm (AVA) is mandatory for:

Solution: DGMS mandates AVAs for all HEMM and surface transport machinery, which includes dumpers, dozers, shovels, etc.

Q2. DGMS Circular mandating AVA for all HEMM:

Solution: DGMS Technical Circular 1 of 2018 made the use of audio-visual alarms compulsory.

Q3. Regulation for machinery safety alarm:

Solution: Regulation 130(2) of CMR 2017 states that machinery must be provided with effective warning devices.

Q4. Reverse alarm should:

Solution: The alarm must activate automatically as soon as the reverse gear is engaged to be effective.

Q5. Audible alarm range:

Solution: The sound must be audible above the ambient mine noise, with 15m as a standard minimum requirement.

Q6. Visual beacon visibility distance:

Solution: The flashing light must be bright enough to be clearly visible from at least 100 meters.

Q7. Color code for reversing:

Solution: Red is universally used to indicate danger or a high-risk maneuver like reversing.

Q8. Color code for moving forward:

Solution: Amber (yellow) is commonly used as a warning beacon to indicate the machine is operational and moving.

Q9. DGMS Circular 8/2008 relates to:

Solution: This circular provides comprehensive guidelines on haul road design and HEMM safety features, including alarms.

Q10. Alarm testing frequency:

Solution: Alarms are critical safety devices and must be checked by the operator as part of the daily pre-start inspection.

Q11. In case of defective alarm:

Solution: A defective alarm renders the machine unsafe. It must be tagged "Out of Service" and repaired immediately.

Q12. Visual alarm usually placed on:

A. Dumper body B. Cabin top C. Rear fender D. None

Solution: The beacon is placed on the cabin top for 360-degree visibility.

Q13. DGMS Circular 2/2013 covers:

Solution: This circular addresses advanced safety systems, including those that monitor operator fatigue and proximity to other objects.

Q14. Maintenance inspection logbook is signed by:

Solution: Statutory logs for machinery must be maintained by the competent engineer and countersigned by the Manager.

Q15. Primary purpose of AVA:

Solution: The alarm's sole purpose is to warn pedestrians and other vehicle operators of the machine's presence and movement.

Q16. Alarm malfunction increases risk of:

Solution: Without a functional alarm, the risk of collisions, run-overs, and reversing accidents increases significantly.

Q17. Flashing light should be:

Solution: This color-coding (Amber for general movement/warning, Red for high-risk reverse) is a common standard.

Q18. AVA system powered by:

Solution: AVAs are electrical devices powered by the machine's battery and electrical system.

Q19. DGMS mandates inspection frequency of HEMM safety devices:

Solution: Critical items like alarms require daily checks (by operator) and formal weekly inspections (by competent engineers).

Q20. Audible alarms used in mines are:

Solution: All these types of sound-based alarms are used for different warning purposes (e.g., horn for presence, siren for start-up).

Q21. Visual alarms include:

Solution: These are all types of visual warning lights used on machinery.

Q22. HEMM means:

Solution: HEMM is the standard DGMS acronym for Heavy Earth Moving Machinery.

Q23. Pre-start check of AVA is done by:

Solution: The operator is responsible for conducting a pre-start check of all safety devices, including alarms, before starting work.

Q24. DGMS violation for no alarm attracts action under:

Solution: Violation of a Regulation (CMR 130(2)) is punishable under the relevant sections (like Sec 72) of the Mines Act.

Q25. Audio-Visual Alarms help in:

Solution: Their primary safety function is to prevent collisions and run-over accidents by warning people.

🔗 INTERNAL LINKS

Related Topic	Read More On...
Opencast Transport	Accidents Due to Dumpers and Tippers
HEMM Safety	Safety Features in Crawler/Tyre Mounted Machinery
Risk Assessment	DGMS Campaign on "Risk Calculator"
Opencast Dumps	Design & Monitoring of Pit/Dump Slopes

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