Damage to a FC bus

An empty fuel cells and hydrogen bus out of service was returning to the refuelling station, when it collided with a low bridge. This resulted in the rooftop hydrogen tanks being sheared off.
The safety valves shut automatically when the hydrogen tanks were dislocated and pipes were torn off. Only a small amount of residual hydrogen in the pipes was released, which is normal in this case.

When the incident happened, there were no passengers on board and the driver was unharmed.

The emergency responders arriving to the scene did not realize that the tanks were not empty, since the manometer that detects pressure between the tank and fuel cell indicated no pressure. Working off this information, they did not use an infrared camera to detect the presence of hydrogen neither took the relevant safety precautions.

On top of that, the 600V electrical system on the roof was damaged but the first responders had not noticed it. An engineer of the bus operator, who had received pictures of the damage, was the first to notice this. The Operator dispatched an engineer who disconnected safely the system.

The INITIATING cause was the decision of the driver to return to the home refuelling station via a shortcut which had not been checked beforehand by the bus operator, he also didn’t take notice of several road signs warning him for a low bridge, resulting in a crash.

The safety systems on the bus worked as expected, but severe shortcomings occurred during the emergency intervention:
(1) The manometer installed on the storage system indicate the pressure in the pipe between the tanks and the fuel cells, not the pressure in the tank. Since that pipe was torn off, the manometer was indication zero pressure. On the basis of which, the fire brigade concluded that the tank were empty.
(2) Another hazard was related to the damaged 600 V system. The fire brigade assumed that the situation was safe because they turned off the main electricity switch. However, this was not enough to zero the high voltage hazard.

The causes related to these aspects of the emergency phase can be attributed to lack of basic technical knowledge of the system, lack of safety instruction and training, and insufficient communication between the first responders and the technical experts of the bus company.

high-pressure on board storage system

The 12 m FC-bus ended its service prematurely because it was running low on hydrogen and was going to return to the HRS, with no passengers on board.
The bus operator has checked beforehand all the routes the bus goes on in service, and selected via a risk analysis. However, the incident did not occur during service and another route was taken, because driver knew a shortcut.

Only material damage.
When the incident happened, there were no passengers on board and the driver was unharmed.
Also among the first responder nobody was hurt.

The emergency responders arriving to the scene did not realize that the tanks were not empty, since the manometer that detects pressure between the tank and fuel cell indicated no pressure. Working off this information, they did not use an infrared camera to detect the presence of hydrogen flames neither took the relevant safety precautions.

The most important takeaway is the crucial need for training of first responders, providing the required technical knowledge and procedures to follow in these cases were a new technology is deployed locally.
Since 2018, the bus company had provided information and offered training that were not accepted or acted on.

A next step, the bus company will meet the overarching safety department of the region, to emphasize the need for training on what to do after incidents.