Delhi’s Signature Bridge audit flags corrosion, faulty monitoring system, repairs

The July audit found corrosion in the skywalk ramp, foundation protection damage and faulty sensors, while officials said there is no immediate safety risk.

A structural audit of the Signature Bridge conducted in July has found severe corrosion in parts of its skywalk ramp, deterioration of foundation protection and a largely non-functional Bridge Health Monitoring System (BHMS), prompting the Delhi government to begin a comprehensive maintenance and rehabilitation programme.

The audit recommended repairs to the steel deck, pylon coating, stay-cable anchorages and expansion joints, plus regular structural inspections. (HT Archive)

The assessment, made public on August 25, carried out after the bridge was handed over to the Delhi Public Works Department (PWD) a few months ago by the tourism department, covered its superstructure, foundations, bearings, expansion joints, steel deck, 154-metre-high pylon, stay cables, approach structures, skywalk ramp, glass facade and BHMS, officials said.

The report found severe corrosion, rust scaling and coating failure in portions of the skywalk ramp steelwork, particularly around joints, splices and fasteners, and recommended detailed assessment and rehabilitation. The BHMS was also found to be largely non-functional, with several sensors damaged or missing and others operating in passive mode. Officials said the findings do not pose any immediate structural safety risk to the bridge.

The government has proposed an overhaul of the BHMS involving sensors for structural temperature, strain, wind, displacement, acceleration, inclination, corrosion, traffic and force, besides a new data-acquisition system and control-room setup.

PWD minister Parvesh Verma said the department was systematically addressing maintenance requirements after taking over the bridge.

“Signature Bridge is one of Delhi’s most important landmarks and a critical part of the city’s transport infrastructure. It is important to recognise that the bridge was handed over to PWD only a few months ago, and our government is now addressing the maintenance requirements systematically,” Verma said.

The assessment also highlighted erosion and deterioration of foundation protection, particularly around river-side foundations. Underwater and subsurface portions could not be fully inspected due to safety and water-flow conditions, prompting recommendations for detailed investigations. Proposed work includes removal of debris and silt, restoration of damaged protective concrete and additional scour protection.

The report also recommended corrective measures for corrosion of the steel deck, deterioration of the pylon coating, protection of stay-cable anchorages, wax leakage, cleaning of expansion joints and drainage maintenance. Deficiencies in certain pendulum-bearing components were also identified.

The report proposed monthly routine inspections, detailed inspections every six months and specialised inspections after extreme weather events, flooding, accidents or other incidents affecting structural integrity, along with a five-year preventive and corrective maintenance programme. The government said concealed or inaccessible defects could not be ruled out without specialised testing.

Verma said restoring the BHMS would be important. “A modern bridge cannot depend only on periodic visual inspections... Restoring the BHMS will give us real-time monitoring and allow engineers to identify potential issues much before they become serious,” he said.

“Maintenance of a structure of this scale cannot be a one-time exercise. The bridge has seen gaps in maintenance in the past, but now that PWD has taken over its upkeep, we are putting in place a systematic maintenance regime,” Verma said.

Meanwhile, PWD has begun preliminary repairs and repeated trial runs of four inclined lifts inside the 154-metre-high bow-shaped pylon. Constructed in 2019-20, they were never opened to tourists due to pending regulatory and safety-related clearances. Two are inclined at 60 degrees and two at 80 degrees. A report on their condition, technical feasibility and safety is expected to be submitted to Verma before a decision on operationalisation.

Built at more than ₹1,500 crore, the Signature Bridge connects Wazirabad in northeast Delhi with other parts of the city. Its viewing gallery was designed to be accessed through the lifts, which will require all applicable safety and regulatory clearances before public opening.