Buses have an arduous lifecycle with short stop-and-start journeys, variations in loading and are often subjected to traffic congestion. While buses have a rigorous maintenance programme taking into account their use, there is still the possibility that some components may fail prematurely, which could lead to breakdown or even result in a vehicle fire.
DVSA has reviewed 242 reports on bus fires and thermal incidents received since January 2020. These included incident reports or safety concerns raised with its vehicle safety branch. It summarised the reported causes to the fires (see pie chart) and assessed fire reporting procedures, maintenance requirements of vehicles and manufacturers’ schedules, concerns of engine bay temperatures (see box), driver training and awareness, and the consequences of bus fires.
The study confirmed that repair practices are partly to blame for causing fires. Some reports identified incorrect repair procedures, such as heat shields left off, or repairs that have not taken into account the effect of the fault on other components. Often when a fault is fixed – for example, overheating – there was no consideration given to what else it may have affected. In addition to fixing the fault, DVSA recommends that technicians consider the degradation that the overheating may have caused. Often such damage is irreversible, and this can lead to premature failures or even fires, it said.
Elsewhere, it noted that older buses are more likely to catch fire. Almost two-thirds of the fires reported (155) were on vehicles 10 years and older; 62 were on vehicles five to nine years old; 20 were on vehicles one to four years old, and five were on buses of unknown age.
Furthermore, DVSA recommends that vehicle manufacturers offer full access to technical maintenance information, that technicians comply with all service instructions, bulletins, and complete outstanding recalls, and that repairs are signed off by a trained and competent person.
But maintenance is only part of the issue, as DVSA found that the decisions made by some drivers have also led to fires. The study confirms that drivers have continued to drive despite the advice of warning systems telling them to stop, or have disregarded these alerts in favour of instructions from the depot to drive.
More broadly, drivers have not always been clear on the evacuation procedures for the particular vehicle they are driving and may not take the correct action at the start of a thermal incident.
Additionally, the driver is rarely interviewed to understand the events leading to a thermal incident. But drivers are often with the vehicle when a thermal event takes place and are the main source of information to understand events leading up to the fault and event.
The agency recommends that drivers understand the warning systems before any journey, know how to use emergency equipment in the event of a thermal incident, and know the procedures for the safe evacuation of passengers. Also, operator staff should not assume the driver has sufficient technical knowledge to ignore warning systems that advise to stop the vehicle.
The study also focused on the fire reporting procedure. DVSA found that a number of reports are submitted a long time after the incident has taken place, some of which are submitted with few details or poor information.
It also found that there is often no investigation into the root cause of the fire, the reports do not include evidence of the events leading up to the fire and do not contain witness statements from drivers or those involved while the incident took place. A number of reports are submitted as ‘cause unknown’.
DVSA recommends that all reports be submitted as soon as practically possible after the incident, and that operators should investigate the cause of the fire and produce a report providing supporting evidence. The study also recommends that DVSA should review submitted reports and, where necessary, request extra information when an operator reports an incident (see also www.is.gd/zutofo).
The study has identified areas where a number of bus fires could have been prevented if corrective action, further investigation of faults or correct procedures were followed.
DVSA has set up a forum with the Confederation of Passenger Transport (CPT) that will look at the recommendations from this study and review ongoing submitted reports which have been provided to the agency. Standard agenda items should consider issues raised by members of the group and CPT, consider what should the best practice to address any issues, develop and implement a communication strategy for any issue which needs taking forward and consider communications to the whole industry.
John Taylor, operational technical executive at CPT, says: “I think the report highlights that operators need to be vigilant, and thankfully they are in the bus industry. We are pleased the report confirms that there have not been any reported fire incidents that resulted in injuries to passengers or others, and that it’s reasonable to conclude that the design of a bus allows for a safe evacuation in the event of an accident or fire. We believe that training and operator procedures are also important.
“As an industry, we have aimed to ‘design out’ issues. For example, the foam on the seating material does not burn any more and bulkheads are put in place and sealed to ensure the fire is kept on the outside. Also, most buses have a fire suppression system in the engine compartment that may save the asset.”
He adds: “We have worked with DVSA and our members and agreed an approach where all parties can work together in a collaborative forum. This will not only apply the recommendations from the DVSA study but create a forum that will allow a continual improvement process to be adopted.”