At any given time, about one-fifth of the city roads suffer from various types of defects, found a study on Chandigarh roads by students of engineering at the National Institute of Technical Teachers Training and Research (NITTTR), Chandigarh.
The study found that most of the damage to the roads was caused by loss of aggregate — coarse particulate material including sand, gravel, crushed stone — potholes and stripping etc.
The study selected seven stretches on V6 roads in sectors 18C, 18D and 31C to identify various types of defects, and their severity.
The investigation found potholes, cracks and loss of material in all these roads. A structurally sound road with good construction material does not have potholes. But all the roads under study were pockmarked by potholes.
The study observed loss of aggregate particles at many locations throughout all the roads. Hairline cracks were present in several areas and a major pothole was also seen in the stretch.
Of all the seven roads under observation, only one was found in ‘good’ condition, the rest were bracketed as ‘fair’.
The V6 roads were mostly affected by raveling, meaning loss of aggregate material (crushed stone, sand, gravel used in the making of road) and least affected by settlement (settlement here means compression caused due to heavy traffic). V6 roads don’t see heavy traffic being the internal roads of the city and thus were found not affected by the traffic but loss of material was observed.
Development and maintenance of roads in Chandigarh is divided between the Municipal Corporation and Chandigarh Administration.
The roads designated as V4, V5, V6 fall under the Municipal Corporation which is responsible for maintaining a stretch of about 1,800 kms.
As per the existing policy guidelines, a road is considered due for maintenance if a period of five years has lapsed since placing last overlay (additional layer of bitumen).
Irrespective of the goodness of surfaces, overlays (additional layers of bitumen) are placed, which means that irrespective of the fact that the road is in a good condition, additional layer of bitumen is added which makes the surface more uneven.
Reason for bad roads
Experts say whenever a road develops cracks or potholes, the engineering wing mindlessly puts an additional layer of bitumen over it without addressing the root cause, which could range from a leaky underground water pipe, seepage or uneven surface et al.
“Without addressing the failures and suggesting treatment measures strengthening was done by placing overlays (additional layer), only to observe at later stages that with time, the earlier defects reflected on the overlaid surface making the roads a case of repeated failure,” the study said.
The study observed that the defects in the road could also be due to poor drainage conditions. The practice of periodic overlay (putting a layer of bitumen and tar) results in raising the road levels that causes functional problems.
At times, a simple overlay does not provide a complete solution.
Also, the overlays alone don’t strengthen the road. The roads also need appropriate surface treatments before these overlays.
What makes a good road
According to Professor Ajay Duggal from NITTTR, a good road is one, which has longer durability, offers a good riding quality and does not develop defects easily and early after being constructed.
Merely putting a layer of bitumen over a defective road does not solve the problem.
The road near sector 17/22 chowk (bus stand road) is a classic example of a good road, which hasn’t deteriorated even after 10 years, he said.
“A simple overlay is not a solution. Rectification of existing defects is very important prior to placing overlay, else the defects will recur. I would rather suggest that thin overlays should be adopted when the road is in fair to good condition. Placing unnecessary thick overlay will result in wastage of material and money. In the long-term unnecessary raising of road levels only leads to higher expenditures,” he stated.
He stressed that preventive maintenance is the key to enhancing the life of any road. It costs less and increases the life of a road. Duggal said while laying a fresh road, proper soil investigation must be done prior to determine the type of soil on which road shall be laid.
Secondly, the authorities should ensure a proper mix with an adequate binder, grading of materials, and temperature control besides ensuring the cleanliness of the surface on which the road is to be laid.
Also important is using the right air temperature, proper laying of the material, compaction and allowing traffic only after the compacted mix is allowed to cool to atmospheric temperature.