Fleet > Planning and Design Standards – Resilient E-bus Ecosystem

1. Fleet

2. Depot

3. Charging Infrastructure

4. Operating Environment

Planning and Design Standards

At the procurement stage, e-bus design and safety standards are established to ensure structural integrity, operational efficiency, and reliable performance across diverse operating conditions, while incorporating preventive measures to enhance safety and disaster resilience. These standards are structured under key safety categories including electrical safety, thermal safety, water protection, cyber security, structural safety and general safety measures, with detailed planning and design recommendations outlined in the subsequent sections.

QnA

Q1. During summer operations, an e-bus driver notices a dashboard alert indicating the battery temperature has reached 34°C while the bus is in regular service.

What is the most appropriate action recommended under thermal safety guidelines?

Continue normal operation until temperature exceeds 40°C Switch the bus to crawl mode and gradually reduce acceleration and shut down the e-bus. Immediately shut down the bus in traffic Ignore the alert if State of Charge (SoC) is above 50%

Q2. A public bus transport agency operates e-buses in a city that experiences frequent urban flooding during monsoon season. The public bus transport agency is reviewing fleet specifications with the OEM before procurement.

Which design and compliance measure is MOST critical to reduce risks from water ingress in such operating conditions?

Increasing battery capacity to reduce charging frequency Ensuring battery packs, connectors, and wiring meet IP67 / IP68 ingress protection standards Installing higher-power traction motors to overcome water resistance Allowing manual driver control to bypass electrical isolation systems

Q3. A public bus transport agency is drafting tender conditions for procuring a new fleet of e-buses to ensure long-term safety and performance.

Which clause should the public bus transport agency include to enable effective monitoring of battery performance over time?

Mandatory use of rooftop-mounted batteries Proof of battery health sharing by OEMs Fixed battery replacement timeline of 3 years Battery sourcing only from domestic suppliers

Q4. During a routine audit, it is observed that several unused USB ports and diagnostic connectors in the e-bus cabin are accessible to passengers.

What is the most appropriate mitigation measure to reduce cyber-physical risks?

Install higher-capacity infotainment systems Enable remote access to all ECUs Restrict physical access and disable unused ports Rely solely on driver vigilance

ELECTRICAL SAFETY

Planning Recommendations

Effective implementation of electrical safety requires targeted mitigation actions by relevant stakeholder, as outlined in the following table to support enforcement and ensure compliance.

S.No.

Activities

Responsibility

Provide dual-socket charging in E-Bus

Provide fuses, circuit breakers and surge protection device

Ensure optimal condition of battery packs at e-bus acquisition stage

Provide for timely replacement of battery packs

Develop safe charging practices and protocols

Provide mitigation of electrocution risk in e-buses

Provide dual-socket charging in E-Bus: The OEM and procurement team of public bus transport agencies provide dual socket charging in e-buses to facilitate flexible bus parking (either direction) enable charging access from both sides or ends, reduce infrastructure points, save space and optimise depot layout plans.
Provide fuses, circuit breakers and surge protection device: These provisions are designed to protect the e-bus electrical system from overloads and short circuits and be easily accessible.
Ensure optimal condition of battery packs at e-bus acquisition stage: Public bus transport agencies are advised to ensure that the supplied battery packs are safety certified by the authorised organisation at the time of acquisition. At the time of acquisition, the battery packs be less than six months old, to obtain optimal performance and safety from the outset.
Provide for timely Replacement of battery packs: Follow preventive replacement or safe repurposing of traction battery pack systems after 5–6.5 years of use or completion of 2500 – 3000 cycles or when the State of Health (SoH) falls below 80%, to ensure continued safety and reliable performance. Public bus transport agencies are advised to include clause on ‘sharing a proof of battery health’ in the tender document, to enable effective battery performance monitoring by the public bus transport agencies.
Develop safe charging practices and protocols: Avoid deep discharging by initiating charging when the battery level drops to 10-20% and prevent overcharging by maintaining an optimal charge level between 85-90%.
Provide mitigation of electrocution risk in e-buses: Use of armoured cables, cable route marker, proper lightning protection and earthing mechanisms are advised to be incorporated in all vehicles as per the requirement specified in respective safety standards.

Design Standards

The following standards amongst others, shall be incorporated into e-bus designs by the OEM and verified by the procurement team.

For electric propulsion systems: AIS 048 and AIS 049

Construction and Safety requirements of e-buses: AIS 038, battery thermal management and use of liquid cooling systems to maintain battery temperatures between 15°C to 35°C.

Traction Motors: The electric traction motor which may be either a single in-line motor or wheel hub motors are to be equipped with an overheating warning and an overheating protection system. When the overheating warning is triggered, the motor’s power be reduced (derated) to lower the temperature and to avoid further risk of overheating or permanent damage. The motors should also have IP 67/68 protection against water and dust ingress.

Recommended Standards

Safety Specification for batteries: ISO 6469 Series
Battery Packs – Impact Testing: SAE J2464; Testing under vibration: SAE J 2380 2021
Safety Standard for Li-battery: SAE J 2929-2013
Safety related warning labelling practice for batteries and other items: SAE J 2936 2025
Recommended Practice for Transportation and Handling: SAE J 2950-2020
Traction Motor protection against water & dust Ingress: IP67/68

THERMAL SAFETY

Planning Recommendations

Successful thermal safety implementation depends on targeted mitigation measures by relevant stakeholders, as detailed in the table below to enable effective enforcement and compliance.

S.No.

Activities

Responsibility

Minimal battery exposure to direct heat through battery positioning

Preferred operating temperature range of the on-board cooling system

Fire Detection and Suppression Systems (FDSS), Fire alarm and FPS for passengers

Compartmentalised Fire Zones on board

Preferred charging period for batteries for optimal temperature range

Parking of E-Buses particularly during charging process

Battery Management System (BMS)

Monitoring battery temperature and safe operating temperature range indicator

Battery discharge alerts and provisions for SOH alerts

Minimal battery exposure to direct heat through battery positioning:  In high temperature operating regions, position battery modules at the belly/ under floor level of e-buses to minimise exposure to direct heat for enhancing thermal protection.

Preferred operating temperature range of the on-board cooling system: As the e-bus battery naturally performs well in temperature range of 15°C and 35°C, maintaining this temperature range is crucial for maximising battery performance, lifespan, and safety by proving an efficient battery cooling system.

Fire Detection and Suppression Systems (FDSS), fire alarm and FPD for passengers: Installation of FDSS near fire sensitive areas especially the battery packs are recommended, to timely detect and supress any fire. Also provide a fire alarm to simultaneously alert passengers and staff for timely evacuation, etc. FPS in passenger compartment need also be provided for pax safety.

Compartmentalised Fire Zones on board: Design to position battery packs in separate compartment, located away from driver work area, and passenger cabin to enhance crew and occupant safety.

Preferred charging period for batteries for optimal temperature range: Charging of the battery to be undertaken preferably during cooler hours.

Parking of E-Buses particularly during charging process: Park e-buses under shaded and adequately ventilated spaces particularly during charging.

Battery Management System (BMS): The BMS functions as an intelligent monitoring and control unit for the battery packs besides other items. It comprises integrated hardware and software, with hardware embedded within e-bus systems to monitor different parameters of battery components and other items. The BMS continuously tracks key parameters such as State of Charge (SoC) estimation, state of health (SOH), useful residual life, power availability, depth of charge and discharge, voltage and current fluctuations and temperature. It also supports thermal management, safety monitoring, communication, computation and real time data logging to ensure safe and reliable battery operations.

Monitoring Battery Temperature and safe operating temperature range indicator: During operations, if the battery temperature is observed to exceeds 32-35°C or other OEM prescribed range, safety mechanisms such as switching e-bus to crawl mode, gradual reduction in acceleration etc. are advised.

Battery discharge alerts and provision for SOH alerts: Driver are to be trained to respond promptly to battery discharge alerts. The first alert may be triggered at 30%, displaying details of the nearest charging station. Subsequent alerts may occur between 25–21%. Below 20%, the bus enters crawl mode, and the driver is instructed to stop the vehicle at a safe location to prevent deep discharge that could potentially imbalance the battery composition.

Design Standards

The following standards shall be incorporated into e-bus designs by the OEM and the procurement team.

Safety standards such as AIS 052, AIS 153, AIS 135, UNECE R100, R107, R66, R95, R29, FMVSS 302 and 305 provide detailed requirements for various safety and other aspects of e-bus. These, inter-alia includes mandatory measures for over-temperature protection, lightning protection, installation of fire extinguishers & FDSS, use of fire-retardant materials in bus bodies, and the Battery Management System (BMS) capable of initiating a three-step disconnection process in case of identified risks.

Battery Chemistry: Use of LiFePO₄ (LFP) batteries, which have better thermal stability compared to NMC/NCA chemistry-based batteries. Additionally, battery modules be compliant with UN Manual of Tests and Criteria Part III, Subsection 38.3 and relevant provisions of AIS 156.

Battery Cooling Systems: Use a coolant /gel-based battery cooling system (e.g. glycol gel) to maintain battery temperature in the optimal range of 24°–32°C. This process typically takes 5–6 minutes, after which the e-bus powertrain starts.

Other Battery Safety Features: Include over-voltage and under-voltage protection, over-current protection, thermal runaway prevention (using phase-change materials or fire-resistant barriers), and cell balancing and short-circuit protection. For fire safety thermal fuses or venting mechanisms shall be provided.

Interior materials and wire insulation within the bus be made of fire-retardant, low smoke compounds to enhance fire safety.

Use of UV-resistant paints and plastics be made to reduce material degradation.

HVAC servicing: OEMS to provide for and ensure implementation of optimal serving schedules of the HVAC system particularly, before and during summer season.

Provide cabin Insulation using insulation films or blinds and installing roof insulation sheets or reflective paints.

Provision of on-board Fire extinguishers: Battery compartments are advised to be fitted with FDSS systems and simultaneously with fire alarms and FPS in passenger compartment. ABC dry powder fire extinguishers are advised to be provided in other high-risk zones such as passenger compartments to safeguard the area from Class A (combustibles), Class B (flammable liquids), and Class E (electrical Equipment) fires; ensuring early containment of thermal events, as per IS 2190:2010 guidelines. International standard NFPA 10, outlines requirement for portable fire extinguisher as the first line defence against fires of limited size.

Compliance with Safety Standards: Global benchmarks including UN standards like ECE R100 and R107 emphasize thermal management, fireproof battery enclosures and safety integrity. Federal Motors vehicle standards FMVSS 302 and 305, and EN 1839 are some of the standards for installation of FDSS in public transport vehicles.

Recommended Standards

Thermal Safety Specification for e-buses: AIS 052, 153, 135, 156
Fire safety specification related to Electrical Installations: IS 1646:1997
International Standards on Thermal management & fireproof battery enclosures: UNECE R100 & R107
FDSS Specification in public transport vehicles: FMVSS 302 and 305 & EN 1839.

WATER PROTECTION

Planning Recommendations

Ensuring water protection requires clearly defined mitigation actions by responsible stakeholders, as outlined in the table below to facilitate enforcement and ensure compliance.

S.No.

Activities

Responsibility

Battery placement and Bus floor height

Water Sensors

Automatic Power Cutoff in case of water ingress:

Battery placement and Bus floor height: Battery placement may be determined judiciously based on local conditions. The battery packs may be suitably fitted on rooftop, and across other suitable locations such as the rear end or other architecturally unused spaces while ensuring the bus remains low-floor and accessible to all passengers. In flood prone areas, floor mounted batteries may be avoided to minimise the risk of water ingress and damage.
Water Sensors: Install water sensors near high voltage modules to enable automatic isolation of these modules upon detection of water ingress.
Automatic Power Cutoff in case of water ingress: The system may be designed to automatically isolate power to prevent damage, and low-voltage circuits such as door systems are recommended to be protected by using fuses and relays.

Design Standards

The following standards shall be incorporated into e-bus designs by the OEM and the procurement team.

Water and Dust Ingress protection: Ensure that battery packs, motor enclosures, connectors, and wiring systems are adequately protected against dust and water ingress. The e-bus components with ingress protection rating of IP67 and IP68 are recommended for complete protection in dusty and polluted environments.
Corrosion Prevention: In coastal or high humidity regions, use IP68 compliant and corrosion-resistant materials or protective coatings to prevent battery damage from salt-laden air and moisture exposure.
All electrical wiring, controls and connectors are recommended to meet at least IP67 standards, in line with AIS 153 and UBS II, to ensure system resilience in varying environmental conditions.
All connectors are recommended to have inbuilt waterproof plugs for unused terminal and features a 360° seal to prevent water ingress. External rubber components or sealing applications may be added to connectors or other parts that require additional protection.

Recommended Standards

IP67: high resilience to water exposure up to 1 m depth for 30 mins
IP68: longer submersion (up to 1.5 meters depth) for a maximum of 30 minutes.

CYBER SECURITY

Planning Recommendations

Effective implementation of cyber security requires targeted mitigation actions by relevant stakeholder, as outlined in the following table to support enforcement and ensure compliance.

S.No.

Activities

Responsibility

Secure Electric Control Unit (ECU) Communication

Protect Controller Area Network (CAN) Networks

Verify Firmware Integrity

Deploy System Firewalls

Restrict Physical Access to on-board ports

Integrate digital-physical data for improvement

Secure Electric Control Unit (ECU) Communication: Secure by ensuring that ECUs are equipped with encrypted communication protocols and authentication mechanisms.

Protect Controller Area Network (CAN) Networks: Implement message authentication and encryption on CAN buses to prevent spoofing, unauthorised access and data tampering.

Verify Firmware Integrity: Regularly verify firmware integrity and apply digitally signed updates.

Deploy System Firewalls: OEMs are advised to include firewall protection across all portals and systems. Further, provision for monitoring the data through Condition Monitoring System (CMS) and Supervisory Control and Data Acquisition (SCADA) platform.

Restrict Physical Access to on-board ports: Restrict access to On-board diagnostics (OBD) ports and infotainment systems; disable unused physical ports (USB, SD).

Integrate digital-physical data for improvement: Combine real time data from the cyber and physical domains to improve awareness.

STRUCTURAL SAFETY

Planning Recommendations

Successful structural safety implementation depends on targeted mitigation measures by relevant stakeholders, as detailed in the table below to enable effective enforcement and compliance.

S.No.

Activities

Responsibility

Provision of mechanism to protect against pressure build ups

Provision for reinforce battery casing

Avoid Vulnerable Parking

Link Uptime Contracts

Safety certification and residual life

Maximum serviceable life of e-buses

Enhance driver support system

Provision of mechanism to protect against pressure build ups: Install pressure release valves in the lower section of the battery packs to manage internal pressure buildup safely.

Provision for reinforce battery casing: A reinforced casing is provided around the battery to protect it from structural damage due to external impacts.

Avoid Vulnerable Parking: Avoid parking near unreinforced buildings.

Link Uptime Contracts: Implement contracts that link fleet uptime and safety performance to timely battery replacement schedules, incentivising preventive maintenance over reactive repair.

Safety certification and residual life: The OEM or battery supplier to provide independent safety certification and residual life analysis for any battery packs proposed for secondary use, in line with standards such as IS 17855 (Part 2) and IEC 62660-2. Structural safety and sturdiness requirements of buses are also available in UBS II.

Maximum serviceable life of e-buses: The maximum serviceable design life of e-buses may be limited to 8-10 years, keeping in view the operating environment, structural integrity under applicable loading conditions following accelerated evaluation of the structural design using FEA or otherwise.

Enhance Driver Support System: Ensure installation of telematics with rear cameras and other dashboard instruments and tell-tale signals to enhance driver support system for improved bus and passenger safety and also protection of the other road users.

Design Standards

Recommended Standards

Safety Certification and Residual Life: IS 17855 (Part 2) and IEC 62660-2

GENERAL SAFETY MEASURES

Planning Recommendations

Ensuring common safety measures requires clearly defined mitigation actions by responsible stakeholders, as outlined in the table below to facilitate enforcement and ensure compliance.

S.No.

Activities

Responsibility

Safe Driving Recommendations – Driver fatigue and driving safety

Safe Driving Recommendations- Driver Health and Safety

Battery related safety sensors

Safety from Technological Obsolescence

Passenger Safety and Security Features

Safe Driving Recommendations

Unsafe driving practices causes e-bus accidents and emergency incidents. To assist in safe driving, procurement team shall ensure that the tender documents include provision of an on-board driver assistance for installation by the OEMSs. Such systems support the driver in safe driving by early identification of potential hazards and providing timely warning for a corrective action, thereby encouraging safer driving behaviour.

Driver fatigue and driving safety: Implement systems for continuous monitoring of driver fatigue level to enable corrective measures and ensure safe driving.
- Equipping buses with Advanced Driver Assistance System (ADAS): ADAS system help improve driving safety by providing Collision Prevention Early Warning System (CPEWS) signals to guide the driver in timely course correction for safe driving. Provision of ADAS in e-buses is recommended.
- Equipping buses with Driving Fatigue Monitoring System (DFMS): The system continuously monitors driver’s alertness and behaviour using real-time driving safety & surveillance inputs, provides timely alerts and driving assistance and helps reduce fatigue related risks, thereby improving overall driving safety. Provision of DFMS in e-buses is recommended.
- Equipping e-buses with Emergency Alerts: Audio-visual alerts for abnormal behaviour of any sub-systems of e-bus are recommended to be provided on driver dashboard for timely corrective action to avoid occurrence of any mishap.

Driver Health Safety: Poor driver health adversely affects driving behaviour and operation safety. The public bus transport agencies should conduct regular biannual health check-ups, including but not limited to eye sights tests, screening for night blindness, blood pressure and other age-related health conditions.

Battery related Safety Sensors

Battery condition be regularly monitored for critical parameters using continuous feedback about such critical parameters for necessary corrective action. Three levels of battery condition monitoring and control provisions, as under, be mandatorily made in e-buses:

Level 1 is at Battery Level: Every battery should come with an in-built thermostat, that monitors the temperature range and as soon as it exceeds the safety threshold, the protective mechanism gets activated to electrically isolate the battery and prevent further energy discharge.

Level 2 is at the Battery Control Unit (BCU):  The BCU monitors battery performance during charging and discharging, including current flow, voltage balance, and thermal conditions. Upon detection of anomalies, the BCU initiates automatic cut-off to protect the battery system.

Level 3 is at the Master Control Unit (MCU): At the vehicle level, the MCU receives alerts from the Battery Management System (BMS) when parameters such as temperature, vibration, or electrical faults exceed defined limits. Based on the critical levels of the parameter(s), the system initiates-controlled power reduction or brings the bus to a safe stop to prevent escalation of risk.

Safety from Technological Obsolescence

The procurement team of the public bus transport agencies, should include in the tender document, features like use of interchangeable spares, sub-systems and the technologies; provision of continual technological upgradation and long-term support of supplies, as follows amongst others:

Technology Upgradation: OEMS of e-bus system and sub systems to provide periodic upgrades for software and selected hardware based upon technological advancement whenever necessary.

Standardise Fleet Systems and sub systems: Public bus transport agencies need to ask OEMs for use of standardised, compatible and interchangeable systems/ sub systems across the fleet so that software and hardware can be easily updated or replaced in parts when needed.

Ensure Long Term Support: Public bus transport agencies should procure e-buses with long term (co-terminating with life of buses, normally 10 years or more) operational and maintenance support from the manufacturer.

Passenger Safety Features

Following provisions related to passenger safety and security be provided in e-buses.

Display Safety Guidance: Install safety‑guide posters or messages inside the bus to assist passengers during emergencies.

Install Fire Protection in Passenger Compartment: Equip compartment of e-buses with Fire Protection System (FPS) to facilitate timely detection, alarm and control. The FPS should comprise of early detection sensors (smoke/ heat), sound alarm, and automatic activation of the high-pressure water mist cylinder/ pump module in case fire breaks out.

Provide Emergency Equipment in Passenger Compartment: Equip the compartment with emergency provisions such as hammers to break the glasses, emergency exit door/ hatches for quick evacuation, fire extinguishers to douse fires, and safety signages for guidance in emergencies.

Enable Passenger Security: Install CCTV and the panic buttons inside the buses for passenger safety and security.

Provide Passenger Seatbelts: Provide seat belts at passenger seats particularly for those without any support/ handholds at front, seat facing aisle and those facing rearward, for improved safety in the event of any sudden acceleration/ harsh braking/ accidents.