PART 2
By Halsey King
halsey@halseyking.com
A bus fire, no matter its size or origin, has a way of stopping people in their tracks. Crowds gather, phones come out, and speculation begins long before the flames are out. In Part 1, we explored the immediate issues that surface the moment a fire breaks out. In this installment, we move deeper into the fire event itself — the behavior of flames, smoke, fuel loads, and the tools meant to stop a small fire from becoming a catastrophic one.
Flame Characteristics
Flame size is dictated by what’s burning, how much of it is available, and what chemicals or compounds are embedded in the material. A simple wood log burns predictably; a wood panel treated with lacquers or stains behaves very differently.
A bus is a complex assembly of metals, plastics, fabrics, foams, fluids, and composites. As a result, a bus fire often produces multiple flame signatures, different sizes, shapes, and colors – sometimes simultaneously.
Flame Color
Flame color is one of the more fascinating aspects of fire behavior. Interior materials such as upholstery can produce colors distinct from exterior components like paint, fiberglass, or metal. While flame color and size may contribute to an investigator’s developing hypothesis, they are rarely reliable indicators on their own. They are puzzle pieces — not conclusions.
Smoke Signatures
Smoke tells its own story. In everyday fleet operations, drivers often report smoke colors from exhaust systems:
• Grey smoke: often oil burning or a mix of oil and water vapor
• Heavy black smoke: typically over-fueling in a diesel engine
• White smoke that dissipates quickly: usually steam from the cooling system
During a bus fire, smoke color and density become part of the broader investigative picture. Like flame behavior, smoke is informative but not definitive.
Fuel Load
Fuel load refers to the total amount of combustible material available. A basket of dry leaves may leave only a faint carbon shadow; a bus full of seats, plastics, and fluids presents a dramatically different scenario.
Under the hood, several common contributors appear again and again:
• Oily engine surfaces ignited by leaking valve cover gaskets and poor preventive maintenance
• Frozen idler pulleys that overheat and ignite fan belts
• Stacked fluids — power steering fluid, washer fluid containing methanol, and brake fluid often clustered on the left side of van engine compartments, creating a concentrated fuel load
Fire Extinguishers
With proper training — and training is the key, a handheld fire extinguisher can stop a small fire before it grows. Federal and state regulations require buses to carry extinguishers in accessible locations, and some states mandate two.
Yet investigators sometimes find extinguishers still mounted in place, burned along with the bus. On rare occasions, an extinguisher is discovered empty on a bus still in service.
Automatic fire suppression systems present their own challenges. They require consistent inspection and maintenance by well trained technicians, and they provide drivers with a certain level of confidence.
Heavy Tire Smoke
Bus tires, especially dual rear tires pose a significant hazard. Each large tire contains roughly 7–8 gallons of oil embedded within the rubber. When ignited, the result is not just burning rubber but burning oil, producing thick black smoke plumes filled with heavy particulates.
These plumes can rise as high as a 12-story building. While dramatic smoke draws crowds, it is extremely dangerous. Behind the spectacle are toxic chemicals, intense heat, and airborne particulates that should be avoided at all costs.
Results of a massive tire fire.
Epilogue
I hope this installment sheds light on the questions you’ve asked over the years about what truly happens during a bus fire event. In my next column, we’ll explore the many strategies and technologies designed to stop a bus fire before it starts.
As for me, I’m off to investigate some of the 360-plus bus fires government reports say will occur this year — each one a new story waiting to be told.
See Halsey King speak at the NAPT ACTS 2026 Conference & Trade Show on October 3, 2026, at 1:00 pm.