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Tarred beyond road level

Last Updated 20 May 2017, 18:50 IST

Twenty years back, when Simon Philip shifted to his new home in Annasandrapalya near HAL, he had to climb two steps from the road to reach the front door. Today, the house is three feet below the road level and gets flooded in a jiffy even for the lightest rain.

One close look at the road and the answer would be clear: It was asphalted at least three times in the last two decades. But every time, the layer of broken tar and ballast underneath was not removed before the surface was asphalted afresh.

Roads across Bengaluru – in the Central Business District or on the outskirts - face the same problem of poor design, execution and quality that triggers the levelling issue. The haphazard patchwork repair of the roads cut by civic agencies including the Bangalore Water Supply and Sewerage Board (BWSSB), Bangalore Electricity Supply Company (Bescom), private and public telecom players, have only made it worse.  

Milling solution

So, how do you ensure that the road level remains the same as that of the houses and commercial establishments on either side? “Internationally, and even the existing Indian standards mandate a process called milling. It is about chewing up the existing top layer, remixing with hot asphalt and maintaining the same level as before,” explains urban architect Naresh Narasimhan.

The current method employed by most BBMP contractors is an easy, lazy approach. The new coating of asphalt laid without milling the existing layer tends to come off as there is no adhesion. But that aids the contractors as road maintenance works are huge money-spinners. Milling costs money, and the Palike prefers low-budget road works.

Simply put, milling is the process of removing at least part of the surface of a paved road. It removes anywhere from just enough thickness to level and smooth the surface, to a full depth removal.

Recycling benefit

But milling has a critical utility besides level maintenance: Recycling. In this process, the existing road is ground up to be used as the aggregate in the new pavement. For asphalt surface, the product of milling is called Reclaimed Asphalt Pavement (RAP). This is combined with the hot mix asphalt for the new layer.

Ideally, city roads should not have a bitumen layer more than 40 mm thick. But due to frequent tarring over existing asphalt, the layer thickness is often beyond 150 mm on most Bengaluru roads.

BBMP is aware that milling, by using old asphalt material ground with machines, could strengthen the roads.

It is estimated that if a more scientific method of road relaying with milling is adopted, the Palike could potentially save 30% of the cost.

Protruding manholes

But no such estimations appear to be making any change in the way roads are being asphalted across the City. The most visible proofs of the continuity of the old approach are the manholes jutting out above the road surface. The rationale is this: The road level will eventually catch up with the manhole level through subsequent asphalting over the years.

Until this levelling takes place, the manhole remains more like an amplified pothole or a dangerous elevation, both risky for motorists. “Manholes once constructed are hard to modify. This whole issue would be avoided if either the manholes are reconfigurable structures or if roads are relaid after removing old asphalt every time, instead of just adding another layer,” feels  Dwarakesh Desai, a commuter.

Cost factor

Milling machines are prohibitively expensive. This is what is BBMP's constant alibi on not taking the milling route to road repair and maintenance. But, as road design and traffic expert M N Sreehari points out, the process is critical to ensure longetivity of the roads.

Old road layers are often replete with potholes, depressions and undulations due to heavy traffic. Milling ensures that these are levelled out and the two layers have strong bonding. “This way, you can avoid layers coming off within one or two months and the roads developing cracks,” says Sreehari.


LETTERS     pointblank@deccanherald.co.in


The system of asphalting roads without scraping must not be accepted or approved by the Government. This will not only increase the height of the road, but also the potholes will not be covered properly since they form air pockets.

After just one rainfall and due to incessant vehicular movement, the potholes open up again. The road will then have to be asphalted again.
Jagadish M

Quality of road asphalting is no good in the city. A heavy rain washes the layer away. Roads have to be laid and relaid scientifically. The manner in which they do the asphalting now benefits only corrupt contractors and not the traffic.

The roads are neither strong nor traffic friendly, and a city like Bengaluru with high traffic density cannot afford to have such a system. We wish to have our roads look and feel like any other road in developed countries as we spend a lot on infrastructure.
Chandra N R Ramakrishna

Layer upon layer of asphalting does improve the standard of a road .Yes there is a problem of draining because of blockage of drain points from the roads. Care needs to be taken to keep the points unblocked or increase the size of drains so that the rain water can be drained out.

The height of the kerbs and medians also needs to be increased to prevent two wheelers crossing from one side to another and also the water overflowing to low-lying areas.

It is the cost, time factor, closure of carriageways and volume of traffic which might be the main deterrents for scraping of old layer of asphalt.It is possible to recycle the old layers if there is a recycling plant.
M S Sharada Prasad


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(Published 20 May 2017, 18:50 IST)

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