Even as experts have suggested “carbon fibre wrapping” to buttress the Palarivattom flyover on NH 66 bypass, the Vigilance and Anti-Corruption Bureau (VACB) has unearthed a stockpile of evidence that points to slack supervision, adoption of shoddy construction methods and compromise on quality of materials, at almost every stage of its constructing, knowledgeable sources said.
Unsafe for heavy vehicles
The flyover will, in all likelihood, be unsafe for heavy vehicles, even after it is reinforced, due to inherent flaws in its construction. It may have to be rebuilt in case the rehabilitation fails, sources said.
The Vigilance probe also sheds light on the collusion between officials of the RBDCK which built the structure, KITCO, which was the main consultant, RDS Projects, which built the structure on the basis of an engineering, procurement and construction (EPC) contract, and those of a Bengaluru-based consultancy firm. There is evidence to suggest that the contracting firm which designed and built the structure unduly adopted cost-cutting practices, in collusion with officials of the two agencies, they said.
Cracks on girders, pier caps
As proof of shoddy construction, they pointed to how shear cracks developed in almost all girders and in almost a dozen pier caps of the flyover which was commissioned in October 2016. Many cracks are getting bigger as evidenced by the fact that many small glass pieces that were kept between them by inspecting agencies are crumbling.
This points to the use of inferior quality concreting mix. An analysis of samples taken by core-cutting proved that grade M-22 concrete was used, instead of M-35 concrete. The strength of M-22 concrete is much lesser. Moreover, inadequate quantity of steel was used. These two aspects led to the cracks.
Faulty bearings
Even more serious is the threat to safety of people using the flyover and the road beneath, due to the faulty placement of bearings beneath the slabs. The bearings have been placed wrongly, including on the 40-metre-long central span. A couple of them have suffered damage. The slabs would have to be lifted to replace them and put new ones in the right position. This is a time-consuming and cumbersome process, it is learnt.
The technical team of the VACB was also shocked to find that mastic sheet/board was used instead of laying mastic asphalt over the concrete. This led to potholes all over the surface of the four-lane flyover within a month of commissioning, due to inadequate binding of the tarred surface with the concrete beneath.
It was also found that adoption of deck-continuity slab method instead of the conventional expansion joints or the joints-free method, is not good for Kerala’s climate. All these point to serious flaws in the construction of the flyover which was to be used by different types of vehicles, including hundreds of multi-axle buses and container lorries every day, the sources said.