The consortium working at São Paulo’s Pinheiros station that suffered a fatal tunnel collapse in January 2007, has hit back at claims it was responsible for systemic failures of design and risk management (NCE 25 June).
A Consórcio Via Amarela (CVA) spokesman said investigations into the catastrophe, which killed seven people, found three unforeseen geological factors that led to the tunnel collapse.
He cited a report written by an independent board of consultants, appointed to assist the official investigation into the collapse by Brazil’s Institute for Technological Research (IPT).
“Unforeseeable” ground conditions
The CVA spokesman said that the consultants’ report had found an unexpectedly weak rock mass above the tunnel, fragile and weathered biotite material at the tunnel sides and the presence of unstable metabasic weathered material all combined to cause the accident.
He added that these ground conditions were “unforeseeable” and had not been detected, despite its decision to drive an additional 20 investigation boreholes as part of the detailed design process.
Thirteen people from CVA, designer and client are due to go on trial in September accused of construction negligence in carrying out the design and build contract.
CVA said the action would be “an unbiased and appropriate forum to judge the case”.