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While the incident appears to have been caused by a blowout, it could also be seen as a tragic combination of many of the factors that play a role in a large number of tanker and tender accidents – especially in tankers that have been converted or repurposed. In this case, NIOSH investigators offered these actions as a way of reducing this particular type of accident.
1. Enforcement of standard operating pro cedures for seatbelt use.
2. Determine safe operating weights for water tankers based on vehicle characteristics.
3. Remove overweight vehicles from service.
4. Identify and correct defects and deficiencies in government surplus vehicles prior to being released to the fire service.
Many communities and fire departments seek to contain or reduce apparatus costs by repurposing or converting government surplus vehicles, milk trucks or gasoline haulers. While dollars may be saved, it’s a cost-saving practice that can put firefighters at significant risk in a number of ways.
A mistake many departments make when using a tanker originally built and designed to carry a liquid other than water is overloading (see Emergency Vehicle Operations, “Are You Really Driving a Fire Truck?” March 1997). Overloading occurs when the conversion of fluid weights aren’t accounted for correctly. Repurposed gasoline tankers could present the worst-case scenario – water weighs more than two pounds per gallon more than gasoline. Some departments set a limit on the amount of water loaded into repurposed tankers, but there’s always the risk the tanker will eventually be filled beyond the set limit and become dangerously overloaded.
And even if overloading is avoided, a partially filled tanker is at just as high a risk of rollover as it is from overloading by the effects of sloshing as it is by overloading. Departments that convert tankers and tenders sometimes use tanks meant for static applications without the tank baffles found in quality fire tankers and tenders. Converting vehicles by slicing or modifying the frame also creates additional dangers by weakening rails and raising the potential of chassis failure. Chassis modification can also create an unstable and often dangerous, higher center of gravity than the suspension – or even an experienced driver – can handle.
Safer tankers and tenders
HME engineers have long understood the importance of building balanced, well-engineered tankers and tenders – with correct GVWRs to match the vehicles maximum loads – and baffled tanks to prevent sloshing and shifting loads. HME has also recognized the need for greater roll-stability, braking and suspension control – especially in the at-risk world of tanker and tenders. New transportation regulations are already on the way that will mandate suspension control systems in the near future – systems that HME is integrating into its fire apparatus, tankers and tenders right now.
HME worked with a provider of suspension and braking control systems, Meritor WABCO, developing advanced suspension control and braking systems for fire tankers and tenders. The advanced electronic stability control systems integrated into HME tankers and tenders automatically sense when there is a risk of directional instability that could lead to a loss of vehicle control and cause a rollover. The technologically advanced control system constantly compares a vehicle’s actual movement to performance models through its integrated sensors. If the vehicle shows a tendency to leave the driver’s steering path, through understeering or oversteering, or if the vehicle exceeds a critical lateral acceleration limit, the system will prevent loss of control by selectively applying brakes to realign the vehicle in accordance with the driver’s intended direction of travel.
While apparatus manufacturers can design and build safer and more stable tankers for the future, a large measure of firefighter safety, especially in the operation of these big rigs, remains in the hands of individual fire departments. Seatbelt mandates and specialized driver training programs are key elements to turning around the alarming rate of accidents and fatalities in tanker and tender operation.