One of the longest overbridges constructed in Kerala, the Palarivattom four-lane flyover is the first structure in the state to be supported by single piers.
In the past few years, the city of Kochi has seen a heavy rush on roads leading to Palarivattom and Kakkanad. The NH-66 (old NH-47) bypass crosses one of the busiest city roads - from Palarivattom to Kakkanad - and is also nearby the busy Edapally junction, which is the meeting point of NH-17 and NH-66 (old NH-47). The heavy traffic faced, made a flyover the need of the hour.
The foundation stone for the project was laid in June 2014 and construction work commenced in September 2014. The Roads and Bridges Development Corporation of Kerala (RBDCK) was the implementing agency and entered an agreement with RDS Project to complete the work within 24 months. The firm quoted Rs 41.28 crore and bagged the contract.
The new Palarivattom flyover finally opened to traffic in October 2016 to decongest the Palarivattom NH bypass junction where the bypass intersects the busy Ernakulam-Kakkanad-Muvattupuzha state highway. What´s more, it is one of the longest overbridges constructed in the state and the first such structure in Kerala to be supported by single piers; 122 girders were placed using heavy-duty cranes.
Civil specs The total length of the flyover is 632 m at a width of 17 m. There are a total of 19 spans in the flyover and the bridge´s pre-stressed central and end span girders are 35-m-long (see box for detailed info). Thirty-seven posts with LED lights are installed in the bridge.
As Sree Kumar, Vice President, RDS Project, reiterates, ´The entire four-lane - around 16.6 m overall width - is supported on single piers, a first for Kerala."
Methods and technologies
´The entire piling work has been undertaken using a hydraulic MAIT drilling machine as against the conventional tripod rig type piling,´ adds Kumar. ´This has helped speed up the completion of piling works in the shortest time.´
Further, cities like Kochi now have several concrete batching plants, where quality assurance is completely ensured. ´We have made use of the best batching plants near the site, as a result of which, concrete was delivered on time without any delays owing to traffic snarls,´elaborates Kumar.´We have used only boom placers and concrete pumps for concreting, which has largely helped in pumping concrete amid heavy traffic.´ The structure has made use of M30 grade of concrete for its foundation, M35 for the sub structure and M40 for the super structure, which ensured consistency in quality and strength. Besides, aggregate and sand were sourced locally.
Space restriction and heavy traffic were the two major concerns. To address this, Kumar says, ´Leaving the required space for smooth traffic, we meticulously planned the concreting and erection of girders in a way that the process until the erection of the structure was smooth. So also, 1 mm GI corrugated deck sheets were used for the central span, avoiding shutter supports and allowing traffic while concreting.´
Also, most RCC girders were cast right below the respective span to avoid long shifting. For the 35-m spans, PSC girders were cast all along the side of the flyover, necessitating shifting. For this, the project made use of hydraulic trailers with turn buckles, so that the girders were properly secured while shifting. Another advantage is that such trailers can be placed in the exact position because of hydraulic steering, which makes erecting the structure easy.
Besides, heavy-duty cranes of 135 mt and 85 mt were used, and heavy supporting columns were erected with cribs to support the girders. Girders could be erected only during night hours.
Cost and completion time
An administrative sanction to the tune of Rs 72.60 crore was granted in October 2013 to build the flyover and to widen around 200 m on either side of the Palarivattom-Kakkanad Road as a four-lane one. The Palarivattom flyover has been constructed at a cost of Rs 42 crore, using funds obtained by the Kerala Road Fund Board as fuel cess from the Kerala government. The flyover was completed within 24 months. Evidently, it's a flyover, like no other!
Height: 6 m
Completion: October 2016
Construction cost: Rs.42 crore
Design consultant: Nagesh Consultants, Bengaluru.
Project consultant: Kerala Industrial & Technical Consultancy, Kochi (KITCO).
Tel: 0484-412 9000.
RDS Project, Kochi, Kerala.
Contracting agency: Roads and Bridges Development Corporation, Kochi.
Spans: (AP1 to P9 = 9 nos) + (P9 to P10= 1 no) + (P10 to P18 = 8 nos) + (P18 to AP2 = 1) = 9 x 22.2 m + 1 x 35 m + 8 x 21.5 m + 1 x 35 m = 441.8 m
Approaches: 2 x 110 m = 220 m
Total length: 661.8 m
Foundations: 1000 mm dia piles = (17 x 4) + (3 x 6) = 86 nos
Pile Cap = (17 x (4,300 x 4,300 x 1,500) + (3 x (7,300 x 4,300 x 1,800)
Sub structure: Pier = 20 (1,800 x 1,800)
Pier cap = 20 (7,400 x 2,200 x 1,500 / 1,000)
Super structure: 9 spans x 6 RCC girders each of 20.5 m + 8 spans x 6 RCC girders each of 19.55 m + 2 spans x 10 each PSC girders each of 32.8 m
RCC crash barrier: At Edges and median
Expansion joints; strip seal type expansion joint every III span and both ends of PSC girders; rest of the span joints provided with deck continuity.
Bearings: All RCC spans four no. elastomeric bearings and both 35 m PSC girder spans with four no.
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