AIS 153 Explained: Key Updates Every Bus Body Builder Needs to Know

Starting September 2025, India’s bus manufacturing landscape will undergo a significant shift with the mandatory enforcement of AIS 153, the updated Automotive Industry Standard issued by the Ministry of Road Transport & Highways (MoRTH). This standard, framed under the Central Motor Vehicle Rules (CMVR), aims to ensure consistent safety, comfort, and quality in bus design, covering both OEMs and non-OEM bus body builders, especially for intercity coaches 12 meters and above in length.

AIS 153 represents a step toward global alignment in bus manufacturing, emphasizing passenger safety, structural integrity, and operational efficiency. While the standard covers a wide range of technical requirements, bus body builders are primarily concerned with the key areas that affect certification, compliance, and passenger experience.

1. Noise, Vibration, and Harshness (NVH)

Passenger comfort is a central component of the AIS 153 framework. The regulations define strict limits for interior noise, vibration, and transient harshness to reduce fatigue and enhance ride quality.

• Noise Limits: Maximum interior noise is set at 85 dB(A) for front-engine buses and 80 dB(A) for rear-engine buses, measured as per IS:12832-2010 standards. This is roughly equivalent to city traffic noise.
• Vibration: The bus structure must have a minimum natural frequency of 5 Hz for vertical/bending modes and 3 Hz for torsional modes. RMS vibration levels vary by suspension type and location, ensuring the bus remains structurally stable while passengers experience minimal discomfort.
• Harshness: The maximum allowable transient vibration is 3 m/s² at the driver’s seat and 10 m/s² at passenger seats, with dominant frequencies carefully chosen to avoid resonance with human body sensitivity. For sleeper buses, accelerometers measure vibrations at driver seats and berths to maintain comfort during long journeys.

2. Intelligent Transport System (ITS)

AIS 153 mandates the integration of modern fleet management and safety technologies, including:

• GPS tracking and real-time passenger information displays.
• LED destination boards.
• Driver behavior monitoring systems.
• CCTV with at least 30-day recording capacity.

All ITS components must meet electromagnetic interference (EMI) and compatibility (EMC) standards, ensuring reliable operation in all conditions.

3. Fire Safety System

Fire safety has become a critical regulatory requirement. AIS 153 distinguishes between bus types:

• Fire Detection Alarm System (FDAS) for seater buses, which detects smoke/heat and alerts passengers and the driver.
• Fire Detection and Suppression System (FDSS) for sleeper buses and school buses, which additionally suppresses detected fires to prevent spread and facilitate evacuation.

For buses below 3.5 tonnes GVW, FDAS or FDSS installation is optional.

4. Emergency Exits

The standard clearly defines the number, type, and placement of emergency exits based on bus length:

• Buses ≤12m: At least 4 emergency exits, including one door and two roof escape hatches.
• Buses >12m: Minimum 5 exits, including one emergency door and three roof hatches.

Key updates include collapsible steps, side-door placement for rear-engine buses, and a prohibition on driver partition doors to ensure unobstructed passenger access during emergencies.

5. Lighting & Illumination

AIS 153 emphasizes interior and operational visibility:

• Driver Cabin: 30–150 lux to read instruments without glare.
• Passenger Compartment: Minimum 50 lux, with at least two night lights in all buses except Type I.
• Luggage Hold: Lighting activates automatically when opened.
• Exit Lamps: Automatically illuminate during door operation or night driving.

6. Engine Power to Gross Vehicle Weight

Buses must maintain an engine or traction motor power-to-GVW ratio of >5 kW/ton, ensuring sufficient power for safe operations.

Certification Procedure

To secure AIS 153 compliance, bus body builders must approach accredited agencies such as ARAI, ICAT, or CIRT. The process involves:

1. Submitting technical specifications, design layouts, and safety feature documentation.
2. Conducting physical testing, including on test tracks as per AIS 153 guidelines.
3. Receiving a Type Approval Certificate after passing all required tests is mandatory for vehicle registration.

Conclusion

The updated AIS 153 norms are more than regulatory mandates—they are a blueprint for modern, safer, and smarter buses. By standardizing comfort, safety, and technology, these regulations elevate the travel experience while helping bus body builders modernize their offerings. Compliance may involve additional investment, but it also strengthens credibility, future-proofs products, and positions manufacturers as leaders in India’s rapidly evolving public transport ecosystem.