This is draft guidance, and we welcome your feedback

Practices and processes that can be applied to maximise the safety of battery electric bus operation. 

For a technical guide on the installing of electric vehicle charging equipment refer to:
WorkSafe Guidelines on Electric Vehicle (EV) Charging(external link)

 

A panel indicated the status of the charger with a soft shutdown button and an emergency stop button

Wall mounted connection with an emergency stop button. (Credit: Kirsten Boardman)

Battery fires

Battery fires, while less probable than combustion engine fires, can be catastrophic and require large volumes of specialised fire suppressants to extinguish. Although improbable, the highest risk time of battery fires is during charging, notably fast charging.

To help manage this risk the Requirement for Urban Buses (RUB) therefore requires a a fire suppression system for high-voltage battery compartments compliant with Australian Design Standard 5062-2006 or an equivalent internationally recognised standard. Storage of spare batteries on site also poses a fire risk.  Public transport authorities should require operators to develop and submit a fire mitigation plan to manage the risk of vehicle or battery fires. This plan should consider the specific characteristics of the depot.

Some potential fire risk mitigation strategies include:

  • Fast charging should take place in an area in which other buses could easily moved away in the event of a fire.
  • Identify a location where a damaged or at-risk bus can be moved to so that if a fire erupts then the damage to other buses and depot structures is minimised. However, towing a bus that’s actively burning is likely to be unsafe so it will likely be more practicable to move the surrounding buses away from the bus.
  • Ideally a bus damaged whilst out on the road should be parked in a place clear of other buses or structures until it has been checked over to ensure there is not additional fire risk.
  • Consider fire risks at both depots and opportunity charging locations. 

Requirements for Urban Buses (the ‘RUB’)

Fire safety measures and procedures for battery electric buses and depots is an evolving area of practice and may need to be retrofitted into depot design.

At current, the industry has largely addressed the fire risk by incorporating rigorous early detection and protection protocols in battery management systems to prevent thermal runaway of damaged battery cells.

High voltage battery electric buses also create additional considerations for incident responders, including emergency services and operator recovery crews.

New training and accreditation for high voltage working is required for maintenance staff, as well as personal protective equipment and static-free tools.

Maintenance

Battery electric buses require less maintenance which enables a move from scheduled maintenance to a diagnostic maintenance schedule. In addition, battery electric buses are more reliable, which may translate to fewer maintenance bays needed and smaller spare fleet requirements.

Battery buses are generally heavier than diesel counterparts, new towing and recovery vehicles and processes may be needed. Another difference is that battery electric buses often have equipment located in the roof which requires more working at heights for maintenance staff.

With more electrical equipment, maintenance of battery electric buses is somewhat simplified. Many issues can be dealt with using laptops rather than in conventional maintenance bays.

Additional maintenance regimes, diagnostics and spares storage space may also be required for the fleet of chargers and dispensers at electric bus depots, in addition to buses.

The inside of a battery electric bus opened up for maintenance

Tranzit’s electric bus mechanic Thomas Nikolaison works on one of the company’s growing fleet of e-buses. (Source: Tranzit)