CHENNAI: The Tamil Nadu highways department’s ambitious 3.2 km Teynampet-Saidapet flyover project in Chennai, touted as the country’s first elevated corridor built above a metro tunnel, has come under the spotlight for its high cost. The four-lane flyover, for which work began in 2024, has an average construction cost of a whopping Rs 195 crore per km, bringing the total project cost to Rs 621 crore.
In contrast, the National Highways Authority of India (NHAI), which follows stricter design and higher construction standards than the state highways, has estimated the cost of its six-lane elevated projects in TN and in other regions at Rs 120-Rs 130 crore per km over the same period, making the Teynampet elevated corridor project costlier by around 50%, according to sources.
NHAI’s projects include the widening of Sriperumbudur-Walajah section (revised estimation) and flyover/bridges being built on Grand Southern Trunk road in Chengalpattu-Villupuram section.
The average per km construction cost of the other recently-completed four-lane flyovers was Rs 95 crore at Koyambedu (opened in 2021) and Rs 100 crore at Medavakkam (opened in 2022). Similarly, NHAI’s 6.9-km four-lane elevated corridor on the Madurai-Natham Road was completed at an average cost of Rs 100 crore per km.
As per official documents, the Teynampet project’s estimated cost, fixed at Rs 482 crore in April 2022, was raised to Rs 525 crore in March 2023 before rising by 18% (`96 crore) to reach Rs 621 crore within a year.
Soil stabilisation, utility relocation jacked up cost
Following the awarding of contract in November-December 2023, civil works of the project, executed by J Kumar Infraprojects, began in January 2024.
The new four-lane elevated corridor aims to reduce the travel time between Teynampet and Saidapet on Anna Salai from 40 minutes to just 10 minutes, while easing congestion at seven key intersections — Eldams Road, SIET College Road, Cenotaph Road, Nandanam, CIT Nagar, CIT Nagar 1st Main Road (towards T Nagar), and Jones Road. This section of the arterial Anna Salai handles 2.45 lakh passenger car units per day.
A senior highways official attributed the high cost of the Teynampet-Saidapet project to several critical factors such as soil stabilisation challenges requiring micro-piling (since shallow foundations prevented conventional piling), extensive utility relocations in a densely-congested area, and advanced construction techniques to minimise pillar loads and safeguard the underground metro tunnel. “Soil stabilisation was achieved using geosynthetic materials like geogrids and geocells, among other solutions,” stated an official document released by the state highways department.
The Teynampet-Saidapet metro line runs 17-18 metres beneath Anna Salai. The highways have drilled up to 7 metres from the road surface to lay the flyover’s foundation. The elevated road spans 2.4 km directly above the metro line, including 460 metres over the Nandanam and Teynampet stations, and 655 metres along the non-metro stretch (excluding entry and exit ramps). In total, 69 pillars are being erected above the metro line, 22 on the non-metro stretch, and 41 portal frames covering the 460 metres over the two stations. As of July, about 30% of the work has been completed, according to official documents.
Industry sources said NHAI projects, typically executed under Public-Private Partnership (PPP) mode, are usually more expensive than state highways projects, which are entirely government-funded. “The estimation of state highways and NHAI projects are arrived at with an anticipation that materials, labour and other expenses will go up by 5% to 7% every year. By all measures, the cost of the state highways project ought to be lower than that of the NHAI unless it’s being executed under exceptional conditions,” sources added.
Even after accounting for inflation and price escalation, the proposed 18.5 km six-lane elevated corridor between Kilambakkam and Maraimalainagar, with entry and exit ramps at three locations, is estimated to cost Rs 3,450 crore, averaging Rs 188 crore per km. Likewise, two upcoming six-lane elevated corridor projects of NHAI – from Maduravoyal to Outer Ring Road and from ORR to Sriperumbudur, scheduled for award in 2025-26 – are projected to have an average cost of Rs 160 cr/km.