Fire Suppression & Environmental Risk Assessment for Coach and Bus Terminals with Electrically Powered Vehicles

By Graeme Warnell, Director, EV-EXBOX

At EV-EXBOX we are becoming more and more aware of the huge knowledge gap there is regarding the risks posed by battery powered vehicles. We fully support the transition to clean fuel vehicles and do not claim EV’s bring more risks than ICE vehicles, but they do bring NEW risks.

From public charging to petrol filling stations, supermarkets, cars showrooms and workshops these risks have either been ignored or as we found out from talking to many operators, they were simply unaware.

As fleet electrification moves from cars to commercial vehicles and large passenger vehicles the batteries become much bigger.

As I travel around the UK, I always stop to look at how we are transitioning from diesel and petrol to electric vehicles. As a keen environmentalist I always try and use public transport whenever I can.

However, when I look at the change in vehicle type from diesel to electric or hybrid, I do not see the type of infrastructure, fire suppression, environmental or public safety changes I would have expected.

I remember the strong smell of diesel in bus and coach depots as I travelled around the country by bus and coach as a student back in the 90’s. As an engineer I remember visiting these sites and sometimes almost not be able to stand up due to the amount of diesel and oil that was underfoot in the bus and coach repair bays.

But as we have moved away from the flammable, slippery, polluting diesel did we really think its electric replacement was totally risk free?

Between 2021 – 2022 I recorded at least 3 bus depots fires all of which caused significant or sometimes total destruction of the facility. The failure of the battery whilst under charging is thought to have caused each of the fires.

As the UK rolls out more and more electric buses and demands faster and faster charging the risk of these fires will inevitably increase. Vehicles and charging infrastructure will get older, small bumps, potholes, speed ramps, seemingly innocuous road traffic accidents may all be impacting the integrity of the battery.

At this point it is important to note an electric or lithium-ion battery fire is very different to a fire in a petrol or diesel vehicle:

1.Explosive gasses are released

2.An explosion typically precedes a fire

3.The fire can easily burn at up to 2000 degrees

4.The battery emits highly toxic fumes

5.The fires are notoriously difficult to extinguish

6.Thousands of litres of toxic firewater are generated

Lithium-ion battery fires are unique and present many challenges to firefighters. The lithium-ion battery fire itself is the result of thermal runaway within the battery. This can only be stopped by cooling the battery. If you extinguish the flames of a battery fire without cooling the battery instead of flames the thermal propagation will result in the release of an explosive vapour cloud. Even batteries as small as those found in e-scooters have caused significant explosions.

What is even more important to remember is that when an electric or hybrid vehicle is parked next to traditional diesel-powered vehicles the end result is a very complex multi class fire.

The following events are rare but as we continue with the electrification of buses incidents like this will become more common.

United Kingdom – Potters Bar 2021

An eyewitness said he heard an “unbelievable noise that sounded like a jet” and he saw a bus had “exploded into a ball of flames”. The fire was believed to have been caused by a battery exploding in one of the electric buses while it was charging.

People reported that the toxic smoke cloud could be seen 18km away with local residents being told to avoid the area and keep windows closed.

A total of six buses were on fire – two electric-hybrid, and four diesel-powered.

Transport for London had to remove 108 London buses from service following the blaze, with a knock-on effect disrupting nine local bus routes.

Stuttgart – Germany 2021

A large fire event occurred in Stuttgart Straßenbahnen’s (SBB) bus depot which destroyed 25 buses on Thursday 30th September. An assessment by the police reported that the fire was probably caused by an electric bus during the charging procedure.

The blaze completely destroyed 25 buses and SSB employees received medical attention during the fire.

At present when I visit any bus, coach, private and public charging facilities I see charging locations have been set out for vehicle access, nicely landscaped, well lit and new chargers installed, but nothing more. So, if you are operating a bus or coach depot either privately or as a local authority you should really be checking the following:

1.Have I adjusted my fire safety plan in line with a lithium-ion battery fire?

2.Have I engaged with the local fire and rescue authorities for their opinion?

3.Do I need to re-assess my evacuation procedures?

4.Can the structural integrity of the depot survive this type of fire?

5.What additional structures may now be at risk due to explosion or excessive heat?

6.How do I control fire water on my site, can I isolate my drains and what retention capacity is there?

7.How do I warn neighbouring properties or businesses of the hazard?

8.What are the risks of the fire spreading or affecting others beyond the site boundary?

The list is not exhaustive, and each location will have its own

Guangxi Zhuang - China 2021

A blaze from one electric bus spread to four other buses on a university campus in southern China’s Guangxi Zhuang Autonomous Region.

After just a few seconds, smoke was seen billowing out from one of the buses. Almost instantly, it exploded in a ball of fire. This caused a second bus to catch fire. The inferno then spread to a third electric bus and before long, a fourth was engulfed in flames as well.

In the event of a fire your only current form of defence will be to call the fire and rescue services who will use well in excess of 10,000 litres of firewater to try and suppress the fire. This firewater will be highly toxic and should never be allowed to enter storm drains, sewers or the environment. If it does you can be prosecuted for it. In addition, if your new charging points have not been included in your fire and risk assessment for the site and they impede previously determined emergency exit routes, or access to firefighting equipment the Health and Safety Executive will definitely be interested as to why.

unique risks and challenges. So, this gives everyone a clear decision to make; are we proactive in managing risk or will we be reactive and look back after a serious fire at all the things we could have done?

The transition to clean energy vehicles has to consider more than just getting the chargers into the ground and switched on as part of the design and construction of charging facilities. We need to keep these sites environmentally sound and safe for their entire lifecycle.

At EV-EXBOX we can help EV charging locations mitigate these risks through our public safety, firewater pollution control and fire suppression surveys and systems. We are also here to help in the surveying of existing EV installations and to input into the development of future sites.

If you would like to discuss electrical charging at any of your facilities, please contact:

Graeme Warnell email: info@ev-exbox.com Mobile +44(0)7766107088