Having authoritative knowledge of Road & Highway construction methods, how do you analyze the construction practices, capabilities and technological status of Indian road construction in comparison to world standards?
India is targeting road construction @ of 20 km per day. This is possible only through use of latest technologies and innovative machines. In the last many years, there have been many advances in highway construction methods especially for National Highways and Expressway Projects. These are mostly executed on Built, Operate, and Transfer (BOT) basis. The Concessionaires have adopted the latest construction practices, which are being followed in other parts of the world, resulting in world-class highways and infrastructure.
Fly ash for embankment construction
As a Director, how do you see the role of CRRI in the development of Sustainable Roads and Highways in India?
CSIR-CRRI has contributed immensely in the development of standards and codes, which are published by the Indian Roads Congress (IRC). The research conducted at our lab has directly gone in to formulations of these codes. It is still playing a lead role in approving new technologies, laying of test sections using these technologies, and monitoring of the performance of these sections. Based on CRRI's report, IRC provided accreditation certificates to many new materials. For example, the technology of Recycling of Flexible Pavements was introduced by CRRI on Delhi PWD Roads and later IRC issued guidelines through its code IRC:115-2014. Similarly, CRRI is the pioneer in development and introduction of cold mix technology in India. This technology is greener, environment-friendly, and most suited to low volume roads.
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| Construction of embankment using copper slag and soil | Road made with waste plastic |
Natural resources like hard stone are depleting very fast and there is a ban on quarrying in many states. Therefore, efforts should be made to use the local materials in road construction. Utilization of industrial wastes and municipal waste must be encouraged. Reclaimed Asphalt Pavement (RAP) and construction and demolition waste are the most preferred and sustainable materials for road construction.
Efforts should be made to use the local materials in road construction. Utilization of industrial, municipal, construction & demolition wastes must be encouraged. RAP is the most preferred and sustainable materials for road construction.
It is commonly seen in India that in just one monsoon, newly constructed roads get washed out, whereas, the normal life cycle of roads around the world is 3 to 5 years. What are the reasons behind it and what steps CRRI suggests to MoRTH/NHAI to overcome this problem?
This problem is encountered in urban areas only. It is mainly due to poor (or not effective) drainage system in these areas. The road cannot last for more than a year if it remains waterlogged during rainy seasons. There are guidelines available for construction and maintenance of side drains, but unfortunately, these are the most neglected part in urban as well as semi-urban areas. You will find that roads on intercity sections of a highway remain intact even after rains.
Pothole repair machine developed by CSIR-CRRI
Historically, flexible pavements have been a preferred choice for road construction in India; more than 90% length of total road network is of flexible type. Now, the emphasis of the government is to construct rigid pavements instead of flexible ones. Both of these have their advantages and disadvantages. Economy depends on several factors like soil conditions and traffic volume. There can be arguments against as well as in favour of these types of pavements. Flexible pavements are easy to construct and maintain. It has been observed that over a period of time, the skid resistance on cement concrete pavements is reduced substantially, especially in wet condition, which becomes the reason for fatal accidents. However, these are long lasting pavements requiring very little maintenance and are very suitable when soil conditions are not favourable. Cement concrete pavements in urban and rural areas wherever the roads pass through, habitations and drainage are not proper and water stagnation is frequent there. Moreover, Flexible Pavements are eco-friendly and sustainable as these can be recycled and re-used with addition of nominal fresh material.
Repair and Maintenance are areas where we still lack. This issue needs to be addressed properly. Each state should have Pavement Management System for its road network and maintenance needs must be prioritised based on budget available in a financial year.
Constructing quality roads not only requires the right material but also highly advanced equipment and machinery for sustainable and timely completion of projects. How strong is India in terms of mechanization and new generation technologies?
Many Concessionaire and other road construction agencies in India have now adequate capability of having highly advanced construction equipment and machinery. Even the proper and continuous utilisation of latest machinery is not done due to non-availability of encumbrance-free land for construction of new highway projects. I strongly believe that in India, we have adequate machineries and new technologies to implement like in any part of the world.
Repair and Maintenance (R&M) of the roads is an area which needs immediate attention as R&M practices in India are outdated, making roads uneven, patchy, and temporarily unusable. What is CRRI suggesting to competent authorities to bring best R&M practices for improved life and riding quality of the roads?
It is true that Repair and Maintenance is one area where we still lack. Though IRC guidelines and methodologies are available for routine maintenance, annual maintenance, renewable coat and emergent repair, are not followed in letter. It is mainly due to budget constraints that we are spending very little on R&M of roads. This needs to be addressed in a systematic way. Each state should have Pavement Management System for its road network, and maintenance needs must be prioritised based on budget available in a financial year. Decision for maintenance should not be taken on an adhoc basis.
Bridge approach embankment constructed with copper slag
Milling and Recycling are one of the best options for resurfacing and strengthening of flexible pavements, especially in urban areas, where levels of roads are increasing by overlaying bituminous layer every 3-5 years. Milling and recycling are economical and environment-friendly techniques. However, it may not be practically feasible in all situations due to construction process involved in milling and recycling. Therefore, it will not be a good idea to make it mandatory for all situations. It should be encouraged and preferred wherever required.
The use of poor quality and impure (muddy) aggregates causes roads to wear out immediately after they are put to use. What can be done to overcome this problem?
It is not correct to say that poor quality or muddy aggregates are used in top layers. Weak aggregates with soil or sand are used in the lower layers of a pavement and their use is permissible as long as they satisfy strength and other characteristics. The poor quality aggregates are not used in wearing course so there is no such case of immediately wearing out of aggregates. As per the guidelines issued by IRC or Ministry of Road Transport and Highways (MoRTH), aggregates having strength more than certain value can only be used in pavement construction. However, some new construction methodologies have also been specified for use of marginal aggregates in granular layer through cement, lime or other chemically treated techniques, but these are not muddy aggregates.
