Hyderabad: Efforts taken up to identify cavities beneath road surfaces that result in instances of roads caving in, by the Hyderabad Metropolitan Water Supply and Sewerage Board (HMWSSB) have started to yield results with some spots already being located in different areas.
Under a pilot project, the HMWSSB had roped in Jawaharlal Nehru Technological University Hyderabad (JNTU-H) team to conduct soil condition tests through Ground Penetration Radar (GPR) technology and identify cavities in Secunderabad area.
The project has the team initially scanning nearly 5 km area using advanced Ground Penetrating Radar (GPR) technology which uses radar signal to image the subsurface of a road. High-frequency electromagnetic waves are transmitted into the ground which reveals the cavities, according to officials.
The JNTU-H team comprising post graduate engineering students and research scholars have taken up the pilot project and so far identified few cavities on RP Road near Hotel City, Belson Taj Mahal Hotel and near Ganesh temple at Marredpally, senior officials of HMWSSB said. The scan of entire earmarked 5 km would be completed in next couple of days and after submission of findings, further action accordingly would be initiated, he said.
On the possibilities of taking up repairs soon, the official said Greater Hyderabad Municipal Corporation was not permitting any road digging till monsoon season in the city, hence the works would have to be taken up only after the rainy season.
Each day, the JNTU-H team has been trying to cover at least one km of road with the latest equipment for which the HMWSSB is paying around Rs 20,000 per day. Initially, HMWSSB had sought to rope in National Geophysical Research Institute (NGRI) for the project but gave up due to financial constraints.
The task was taken up following incidents of roads suddenly caving in at major thoroughfares last year and causing worries about the safety of road users. A portion of 600 mm diameter pipeline was damaged at Clock Tower in Secunderabad when the road caved in here apart from affecting traffic flow.
To avoid recurrence of such incidents, the water board has taken up the task of conducting soil condition tests and identifying cavities to take up repairs accordingly. The problem of road caving, senior officials added, was mainly due to ageing 600 mm diameter pipelines which were laid decades ago. These pipe lengths criss-cross the city for a length of over 120 km.
Analysing pineline damages
It was a close shave for motorists on the NTR Marg at Hussain Sagar on September 23, 2016 as a portion of road caved in the afternoon following a heavy downpour. About one metre trench was formed near the main entrance of NTR Park as the road caved in though none was injured in the incident.
It was a 1,800 mm diameter sewer line from Somajiguda connecting to the Amberpet Sewerage Treatment plant via GHMC Head Office and Hyderguda that was affected.
HMWSSB had roped in a technical consultant from New Delhi to scan and assess the quality, life and damages if any, in the underground pipelines surrounding areas of Hussain Sagar. There are several 1,800 mm diameter and 1,600 mm diameter underground pipelines in the city. The majority of the sewer lines surrounding Hussain Sagar are 1,800 mm diameter pipelines.
A car-like device mounted with surveillance cameras and flashlight was suspended in the pipelines. Placed on a wooden plank or a floating material, the device captured images and the same were stored in the memory card placed in the device.
Based on the images, experts assessed the quality and strength of the pipelines. This had helped in studying the corrosion patterns and also to detect cracks and other damages, if any in the pipelines, said an official.