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Flaws many in the making of bridge: Expert

Calcutta, May 21: Jurgen Dorbecker, the German structu-ral engineer who used to supervise the construction of the Second Vivekananda Bridge, had listed several 'major incidents' since January in his final report.

The cited instances ranged from the malfunctioning of a gantry crane to missing reinforcements and the failure of a grouted joint to cracking concrete.

The report was submitted on May 12 with L&T project manager T.S. Ananthakumar. Copies of it were sent to Lala K.K. Roy, the CEO of project owners Second Vivekananda Bridge Tollway Company Private Ltd, and L&T executive vice-president J. Ganguly, among others.

Days before a portion of the bridge connecting Calcutta and Howrah caved in on Friday, Dorbecker had told The Telegraph that the entire structure could collapse in five to seven years.

In his final report, he wrote that the failure of the crane in the main bridge's pre-cast yard on January 5 was triggered by failed welded joints, a result of poor workmanship.

During an inspection on March 29, the resident engi- neer found that 84 reinforcement bars were 'missing in the concrete slab while comparing with the drawings'.

The explanation from the on-site engineer-in-charge ' he was 'under pressure from his superiors to achieve progress'.

Dorbecker also observed in his report that the steel shutter for the upper pylon 'is not matching with the requirements of the design drawings in dimensions'.

The report says: 'The contractor (L&T) has been advised by SVBTC (Second Vivekananda Bridge Tollway Company) and also CES/PB (supervising engineering agencies) that this is not acceptable and has been asked to review the entire formwork'. The contractor is avoiding following instructions by SVBTC and instead, is proposing to paint the entire pylon P9 to cover up the badly repaired joints.'

Dorbecker's document adds that the contractor 'has made no attempts to proceed with grouting and/or protection of PT bars' in the already installed segments. 'Rust and future failure of the PT bars and PT strands can be expected.'

On the failure of Joint P9 ' 11D to 12D ' on April 26, which prompted a stop-work order by independent engineer Schlaich Bergermann, the report says: 'It has become clear after inspections by all parties that no grout had been applied in the web areas of the segment'.'

Dorbecker also reported a 'large number of cracked-up concrete' portions, 'clearly visible from the inside of the segments', exposing the PT bar connections to moisture and consequent rusting. 'It is certainly not acceptable just to cover up these cracked areas as under the load of traffic, the bridge will vibrate and patch-up work will simply fall off,' he warned.

The German engineer felt that quality control at the main bridge's pre-cast yard and other work areas need to be 'improved considerably'.

Two workers died and two were seriously injured in Friday's cave-in. Labourers stopped work demanding safety measures and blaming L&T for using substandard material. They alleged that the iron rods used in the segment that crashed were of poor quality.

L&T had yesterday termed Dorbecker's allegations 'baseless' and referred the issue to the Second Vivekananda Bridge Tollway Company. The company's chief executive officer, Roy, said the German expert had been 'eased out' for 'shirking responsibility'.

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