Noida: The numerous
cave-ins are due to lack of proper drainage system and poor
planning of roads, said experts. Inferior material and improper compacting only add to the problem.
Experts from Central Road Research Institute (CRRI) say that a three-layer compacting of bitumen (made from a binding organic material from byproducts of crude refined oil/petroleum and tar) is essential. However, this is seldom done.
Moreover, the diametre of the drainage pipes used on expressways and flyovers is anywhere between 1.2 to 1.5 metres whereas it should be 1.8 metres. These drainage pipes should be placed at every 250 metres on the flyover to allow proper drainage of water.
“While the entire Yamuna expressway is on embankment and that too far away from urban areas, its drainage pipes are placed at around 600 metres with a diameter of 1.5 metres only. It cannot be compared with other flyovers,” said Dr S Velmurugan, senior principal scientist, traffic, engineering and safety division, CRRI, New Delhi.
According to K Sitaramanjaneyulu, chief scientist, pavement evaluation division, CRRI, a three-layer compacting of bitumen roads—a binding organic material made from the byproducts of refined crude oil—is used in road construction. “The three layers include 1) base course - consisting of sand, morang, minutely crushed stones 2) binder course - consisting of chiselled stones and 3) wearing course - comprising aggregate of fine dust, limestone, stones and bitumen and tar,” said Sitaramanjaneyulu.
Along with the mandatory three layers, Dr S Velmurugan maintained that utility pipes such as water, sewer and drainage pipes should be segregated all along the urban road. “The main problem of road cave-ins are a result of improper drainage. If the drainage is blocked or not properly desilted without requisite slope, then water retention is inevitable on the road. The longer the water retention, the more damaging it is for the road. There should be no compromise on proper drainage,” said Velmurugan.
As regards roads in low-lying areas or underpasses, Velmurugan maintained that improper desilting (sand clogs) and lack of use of pressure pumps leads to waterlogging, damaging the road. “For a well maintained road, drains should be cleaned, desilted and pressure pumps ready for use to draw out retained water much before a downpour. But what we normally see is action only after a downpour,” said Velmurugan.
