The road sign that crushed a car on the Tullamarine freeway at the beginning of the year collapsed due to a missing plate stiffener, which was not seen as compulsory safety checks were missed, according to a VicRoads report into the incident.
The Vic Roads report said essential stiffener plate was missing from the structure, which led to a progressive fatigue crack that caused the four-by-five metre signto crash onto a car driven by 53-year-old mother Nella Lettieri, who survived virtually unscathed.
The plate in question is designed to strengthen the attachment of the sign to the gantry. Two other signs were also found to be missing the plates, and were promptly removed from the freeway.
VicRoads also confirmed that weaknesses were found in quality control and that necessary inspections of the equipment were not carried out.
Construction and maintenance processes are now being given a higher level of scrutiny and are being revised, so that in future, contractors and subcontractors are more closely supervised and their work is quality controlled.
VicRoads has confirmed that signage company CPB Contractors, a subsidiary of the multinational Cimic Group, has already devised measures to prevent an incident such as this one.
Some of the measures include increased monitoring of offsite suppliers and subcontractors; improved processes that require subcontractors to show that fabrication, construction and installation adhere to approved designs; and breaks in the design and construction process to allow time for verification of essential quality and safety elements.
Multiple audits by VicRoads, Major Road Projects Victoria and Transurban have revealed that what happened in January was an isolated incident.