Eliminating hazards related to brakes and brake failure

In the event there is a failure to engage brakes or, if for some reason a vehicle’s brakes do fail, the consequences can be fatal. Vehicles can unexpectedly lurch forward or begin rolling uncontrollably. We investigated some control methods and found the standards and requirements around brakes, brake failure, and rolling vehicles varies significantly between different countries, states, and companies.

Some basic controls are consistent across the industry, including:

Installing fit-for-purpose barriers to prevent uncontrolled vehicles and plant going over embankments or into buildings, workshops and other areas where people may be located.

Selecting as level as possible ground when parking in a non-designated area, and parking across the slope with the steering wheels positioned to use gravity to prevent the vehicle from rolling away. Developing parking procedures in line with appropriate risk assessments, situational factors such as ground gradient, manufacturer’s instructions and current practice in the industry.

Continuously educating on parking procedures and the importance of fully applying the hand brake when parking.

We also found other more stringent controls that can and should be explored include the use of chocks and park break alarms. Governing bodies in some jurisdictions outline specific standards, while in other jurisdictions it is left to the discretion of individual organisations to mandate minimum requirements.

1. Wheel Chocks

Wheel chocks are an effective control measure to prevent uncontrolled rolling, providing control in addition to the park brake alone.

In the USA, the Mine Safety and Health Administration’s (MSHA) Standard for Surface Operations outlines parking procedures for unattended equipment. It states ‘Mobile equipment shall not be left unattended unless the controls are placed in the park position and the parking brake, if provided, is set. When parked on a grade, the wheels or tracks of mobile equipment shall be either chocked or turned into a bank.” Some organisations, including Smithbridge Guam, have decided to follow a more stringent policy on the use of wheel chocks. “We decided to implement a standard of 100 per cent use of wheel chocks and emergency brakes when mobile equipment is unattended, even on flat ground,” said Mellanie Pascual, Occupational Health & Safety Administrator at Smithbridge. “This is more stringent than the MSHA standard, but we felt this would encourage the right behaviour and habits in our workforce.”

WorkSafe NZ issued a Technical Bulletin in July 2018, which was developed in consultation with and was endorsed by the Commercial Vehicle Safety Team of the New Zealand Police, and the New Zealand Transport Agency (NZTA). The Technical Bulletin recommended correct maintenance and adjustment of Cardan shaft brakes in particular, but the Bulletin’s recommendations on chocks are relevant for all vehicles.

600mm

Figure 1: Wheel Chock

150mm

Wheel chocks should be chosen to ensure their size and design will keep the vehicle stationary on the steepest slope on which the vehicle is required to be parked. A wheel chock should be approximately 25% of the diameter of your vehicle tyre and fit snugly into the tyre (e.g. a 600 mm diameter tyre would require a 150 mm high wheel chock). Source: Worksafe NZ

2. Park Brake Alarm

SafeWork Australia’s study on work-related fatalities involving trucks also revealed that most (25 of the 34 fatalities) involved a truck driver who had exited the vehicle to undertake a task and had not put the brakes on properly. Additional controls are essential to remind operators to ensure park brakes are appropriately engaged. This includes warning alarms to alert the operator if the parking brake has not been engaged when the vehicle door has been opened, or systems that automatically engage the parking brake when sensors in the seat detect no pressure and doors have been opened, or the engine is turned off. Owners must ensure park brake alarms work whether the ignition is on or off and that the alarm continues to sound until the brake has been engaged.

In New Zealand, construction company Fulton Hogan has recently implemented more stringent minimum requirements concerning brakes for subcontractors and hired in plant. In 2017 Fulton Hogan updated their Vehicle Standards to mandate park brake alarms, either compulsory upon purchase or through aftermarket retrofit installation.