Plug pulled on bendy buses

A faulty turntable plug could see hundreds of bendy buses taken off roads across Australia

Plug pulled on bendy buses
Plug pulled on bendy buses

By David Goeldner | May 18, 2012

A turntable fault in an articulated ‘bendy’ bus which led to a peak hour crash on Queensland’s M1 motorway in March has led to a state-wide product safety alert which could spread across Australia.

Queensland’s Transport Department issued the alert this week following an investigation which uncovered the cause of the crash.

A Clarks Logan City bendy bus careered into a siding on the M1, stopping Brisbane-bound traffic for several hours on March 30.

At the time the operator did not blame its driver for the crash, which has now been vindicated by the investigation pointing to a faulty plug connection in the mid-section bus turntable.

The Queensland Government’s safety alert suggests the crash was caused by the loosening of a Hubner Generation 2 Proportional Valve Solenoid Plug.

The plug forms part of an articulated bus’s electronic system, controlling bus levelling.

According to the Queensland Government report, the trailer section of a Volvo B12BLEA articulated bus travelling inbound to Brisbane in the left lane of the Pacific Motorway began to sway uncontrollably.

The bus consequently swerved out of control across two traffic lanes and crashed into the centre concrete barrier, rotating 180 degrees across all three lanes, colliding with the motorway guard rail before finally coming to rest.

While buses potentially affected by the fault can travel to speeds of 50kms without incident, Clarks Logan City has taken its three ‘Generation 2’ bendies out of service given the high frequency of highway and busway running into Brisbane at much higher speeds.

"It’s a big impact for us because it means three of our four articulated buses are off the road," Clarks Logan City CEO Graham Davis says.

"Before we put our buses back on the road I need to ensure a fail-safe replacement component is put in its place."

While Clarks Logan City buses are all Volvos, the fault isn’t limited to just one chassis supplier and it only affects the second generation Hubner mechanism.

The region’s largest operator – Brisbane City Council – remains unaffected by the safety alert given its articulated buses are fitted with an earlier version of the turntable mechanism.

However there are several articulated buses in service across Australia, fitted with the second generation unit which may be affected.

Queensland Bus Industry Council Executive Director David Tape says there could be as many as 300 buses in service across Australia that may be affected by the fault.

"If the device isn’t working in the way it is meant to work, there is no alarm sent to the driver," he says.

"This component (the plug) had dislodged, which meant the circuitry wasn’t complete.

"My understanding is that the investigators ruled out any driver error because the driver wasn’t changing lanes and the vehicle became uncontrollable around the linkage at the turntable."

Tape says affected articulated buses may start to sway when the vehicle reaches speeds beyond 60 km an hour.

"Operators may not be aware of a faulty device if the bus doesn’t reach the speed required to start the vehicle swaying," he adds.

"Any articulated bus in Australia that has that componentry in it may be at risk."

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