Road construction experts as well as OEMs, vouch for the efficacy of intelligent compaction technology lauding the way it has led to improved roads. It is one of the most significant technological developments for the road construction sector currently, and offers a potential quantum leap in road construction in terms of quality and performance of the end product. Agith G Antony tracks the pattern in global development of compaction technology; views product offerings from major players in India and explains how the contracting fraternity has responded to the advancements in technology.

THE level of compaction during road construction is one of the most critical aspects, directly reflecting in the outcome of the quality of the road being constructed. The asphalt mix design, the selection of roller / compactor with its operating weight, vibration with its characteristic variables of frequency and amplitude, the correct operation and handling of the roller/compactor all play vital roles in the quality of the end product. Globally, a number of the leading firms such as Fayat Group, Dynapac which is part of Atlas Copco, Hamm which is part of the Wirtgen Group, the Amman Group, JCB and Volvo have designed sophisticated compaction controls technologies that have been integrated into the machines to optimise efficiency of compaction. Referred to as intelligent compaction (IC) technology, these systems use a combination of equipment to measure the compaction carried out and to monitor the heat of the asphalt mat. Most of these latest systems minutely document the work carried out, showing the operator / contractor what compaction has been done and providing a digital record that can be stored and checked if required. Using these systems, an operator can optimise the output; moreover, it helps the operator know which area of the asphalt mat has to be compacted before it cools.. Most of these latest systems document the work carried out shows the operator/contractor what compaction has been done and provides a digital record that can be stored and checked if required.

Says AM Muralidharn, President, Volvo India, "The intelligent compaction system is a state-of-the- art technology which is a combination of the absolute measurement technology with the regulation system that uses measured information to adapt the equipment continuously to required conditions. This system controls the different compaction parameters of the roller: amplitude, frequency and working speed (impact distance). The intelligent compaction rollers are also equipped with global positioning system (GPS) measurements and a documentation system that allows for continuous recording of the roller`s location, the number of passes and any corresponding stiffness-related output. The IC system goes on to check the possibility of under- compaction, over-compaction or other problems and offsets extra expense, too.

"Intelligent compaction involves the use of compaction measurement systems which enable control of different parameters of the roller such as the working speed, amplitude and frequency. The rollers are equipped with sensors that relay the data to the on-board computer, where the operator can monitor the compaction progress on the computer screen. The digital compaction analyser shows how many passes the roller has made, whether it is with high vibration, low vibration or static pass, the relative density after each pass, when the compaction is complete, and the temperature at every pass," says Sudhir R Hoshing, Chief Executive Officer, (Roads), Reliance Infrastructure.

Speaking about the technological trends in the compaction equipment segment, Blesson Varghese, Managing Director, Marini India, Fayat Group had this to say, "Several key trends are emerging in the asphalt compaction market with the development of the latest generation machines. Performance and productivity remain key issues for compactor manufacturers, with firms keen to maximise output from their latest units. Ease of use and improved ergonomics are what for manufacturers target, since they have long recognised that more comfortable machines can be operated more productively and for a longer time. Similarly, improved visibility allows machines to be operated more safely and to further boost overall productivity. "According to him, as the IC roller moves along the work surface, it measures the vibratory energy reflected from the material being compacted. The energy numbers attained have a direct correlation with the density readings from a proven testing device. A visual display shows measurements as the roller moves over the material. All the roller operator has to do is achieve the same energy value from the material over the entire surface."

Blesson elaborates on the trends, "Worldwide, we are witnessing two major trends. The advanced markets like Europe have some very high-tech equipment, which assure customers high levels of safety, productivity and efficiency. In the developing world, the focus is still on ease of operation and application of new technologies in compaction. These markets are growing but they are very price-sensitive, which prevents the use of modern technology to boost speed, efficiency and efficacy. The larger projects, however, demand intelligent compaction."

According to Girish Dixit, General Manager ? Engineering, Wirtgen India, Hamm compactors can be offered with intelligent compaction systems like Hammtronic and HCQ systems. Hammtronic is a microprocessor ?controlled machine management system which links, monitors and controls all important machine functions and frees the machine operator for other activities. Girish says, "The Hammtronic system adjusts the engine performance to specific operating conditions, to operate the machine with extremely low fuel consumption. All the information the driver needs is displayed on the operating console with information display. By monitoring and regulating central machine functions, the Hammtronic prevents operator errors and enables the roller driver to concentrate on optimum rolling results."

Hammtronic has the following components: engine management, drive control, anti-slip control, vibration control and information display. The Hamm Compaction Quality (HCQ) system provides a powerful construction site tested tool for Continuous Compaction Control (CCC) in earthworks and Continuous Asphalt Compaction (CAC) in asphalt construction. The HCQ system includes asphalt temperature display, HCQ indicator, HCQ printer, HCQ GPS navigator, etc. The advantages of the HCQ indication systems are even compaction, detection of weak points, minimising the number of passes, avoiding over-compaction and loosening up, and the fact that the conventional soil test method for load- bearing capacity are not necessary.

Girish adds, "Soil compactors can also be supplied with the compactometer, which measures the relative density of the compacted surface. The compactometer senses levels based on the drum bouncing, which is dependent on the level of compaction. With the help of the compactometer, the operator needs to use only an optimum number of passes and reduce dummy passes. Reduction in the number of passes will reduce the operating cost of the machine."

Says Divakar Marri, Head - Corporate Planning & PMO, Ramky Infrastructure, "With the intelligent compaction system, the compaction performance of a roller can be much improved. IC rollers greatly improve the quality, uniformity and long-lasting performance of pavements today. Using vibration and a system to collect, process, and analyse the measurements in real time, IC rollers are able to compact greater amounts of pavement with fewer passes than the traditional static rollers, sometimes in a much shorter time. In short, IC efficiencies ensure time, cost and fuel savings."

According to Nitin Lall, General Manager, Atlas Copco Construction Technique, the intelligent compaction system for soil compaction and asphalt compactions are different. He says, "In soil compaction, ground conditions are measured continuously, density increases after each pass and the operator monitors the process on an on-board computer. A GPS operator can monitor whether the compaction is uniform in every location of the bed. In asphalt compaction, primarily, the temperature of the asphalt mat is measured and the complete compaction process is analysed. Again, the operator can monitor the complete compaction process on an on-board computer. GPS tools confirm whether every corner of the bed is properly compacted."

Prantik explains the working of the Compaction Analyzer, which is a very advanced system. "The system provides the data of every point of the bed that one is compacting; this gives one the relative density achieved after each pass, the increase or decrease of density after each pass, the vibration frequency, amplitude and also the speed of the compactor. Through an on-board computer, the operator can see the entire compaction process. A lot of research and innovation work from the Dynapac High Compaction centre is behind this accurate and intelligent compaction measurement system."

Says Rohit Punjabi, Assistant Director (Strategy Development & Marketing), LiuGong India, "Intelligent compaction systems automatically measure and control the energy output of a roller drum. Though each manufacturer's system is different in its specific execution, all are designed to work in generally the same way, measuring and reacting to the changing stiffness and material being compacted. The benefits in having an intelligent compaction system fitted into the compactors are more than multiple. It is not only about deriving the desired quality of work but the added benefit to the equipment in terms of fuel efficiency and other factors are of considerable value. Moreover, maximising compaction density, minimising material damage and avoiding mistakes are other benefits associated with intelligent compaction systems. The intelligent compaction system goes on to check the possibility of under- compaction, over- compaction or other problems, and as a consequence, goes on to offset the extra expense or potential damage to the contractor."

Indian scenario

Says Blesson, "While intelligent compaction has only recently started taking off in India, the technology has been used successfully in Europe for nearly a decade." According to him, the penetration of IC technology in India is minimal. Blesson reasons why: "We do not have any intelligent machine in India; this is especially because the ministries/authorities do not specify the same. The world has progressed by leaps and bounds dramatically in the last few years. India is no exception and we envisage a future with intelligent compaction in this great country. It will take the total effort of specification committees, consultants, engineers, statutory boards/law-makers and of course, committed manufacturers like Bomag, to facilitate India's seat in the field of construction excellence and precision control technologies in the compaction arena."

With regard to the product offerings to the Indian customer, Blesson says, "We offer Bomag Asphalt Manager II on both our articulated and pivot-steered tandem models as optional equipment, a system which automatically measures, regulates and documents changes in compaction. The Asphalt Manager automatically optimises compaction performance whilst rolling. The system continuously measures the load-bearing capacity of the material to be compacted and it always provides the maximum compaction performance achievable. The compaction progress can be monitored on a special display, the Bomag Operational Panel (BOP). The display also informs the operator about the current asphalt surface temperature, roller speed and the effective amplitude being used." Equipment India tried to get feedback from the actual users, the road contracting fraternity. Have they started using the IC rollers, and if not, why? According to Sudhir, the IC technology is at a nascent stage. He says, "Dearth of engineers skilled in operating such technology machines and high costs are some of the reasons we haven't started using such compactors." Divakar supports this view. He says, "Performance behavior and the cost-saving analysis of IC technology-fitted compactors has not yet been done meticulously." He further adds, "On the other hand, a greater acceptance of intelligent compaction systems have to come from the contractor fraternity which has to educate itself in understanding the advantages the technology offers."

According to Muralidharan, the road sector in India is witnessing a constant upgradation of technologies and implementation of new technologies as the project completion timeframes are getting narrower. He says, "Presently, Volvo is offering two models of compactors in India, the SD110-11T soil compactor and the DD100-10T asphalt compactor. These machines are being manufactured at Volvo's Peenya plant in Bangalore. The SD110 model soil compactor with its unique Infinitely Variable Frequency System (IVFS) allows customers to handle different types of soils in different applications. It is also designed to handle different sizes of aggregates as per the current specifications laid down by the road authorities." He adds, "Road authorities are adopting the usage of different types of asphalt mixes to meet varying structural design requirements as per the type of roads. Hence, the compactors are being used for varying material types and applications. The Volvo DD100 asphalt compactors are designed to meet these requirements with 9 frequency and 8 amplitude settings."

Muralidharan further adds, "At Volvo, we offer customers the lowest cost of operation. We are constantly innovating to make equipment fuel-efficient, with reduced emissions and environmental impact. Safety is one of the main areas which need more attention in terms of the operator, equipment and site personnel. Safety being one of the core values of the Volvo Group, we are the first and only manufacturer to offer a Roll Over Protection System (ROPS) canopy as a standard fitment in the compactor models in the market. Also, Volvo compactors are designed to offer 1 m x 1 m operator visibility in both the front and rear directions so as to ensure superior visibility for the operator. Volvo soil compactors are fitted with Volvo engines offering the benefit of better fuel efficiency and productivity, thereby enhancing the overall efficiency of the compaction job."

According to GVR Murthy, Head - Construction Equipment Division, Escorts, there is a definite change underway, especially in the roads segment. He says, "Our road specifications are of international standard. Going back to the fundamentals of crushing and laying, if you get the correct raw material for road-making, 60 per cent of the problems is solved. Look at the specifications of the aggregates. People would have never thought that a road needs to have an aggregate of good size and shape. And then people started realising that to get a good quality road, one needs good aggregate, shape and size. Then they went forward and focused on cost savings because less bitumen needs to be put on the top. If there is right compaction, it adds to the cost saving. When it comes to the size of the road, we are at par with global standards. "

Murthy further adds, "We are working on the concept of intelligent compaction. People have been talking about intelligent compaction and I don't know if it is hype or not. The cost of making roads depends on how well and how fast you compact it. And there is always the question about reaching the optimum and required levels of compaction and the number of passes required to attain that level. It is common practice that once the compaction is measured, the foreman insists that another pass is taken, a kind of quality testing. If that gap can be done in four passes and one more pass is added, then immediately the cost goes up by 20 per cent. That optimisation has to take place. That is where the concept of intelligent compaction is being worked out. We have not dealt with it specifically at Escorts or within the country till now, though it is quite popular in Dubai."

Says Amit Gossain, EVP - Marketing, Business Development and Corporate Affairs, JCB India, "Compactors have played a key role in building India's rural, urban roads, and highways. JCB is continuously investing in R&D to come up with machines that achieve optimum compaction with a minimum number of passes to reduce the overall operating cost. At JCB, the latest equipment is designed keeping the customer requirement and operator comfort in mind. We have a wide range of compactors available in the market which can be used to meet different requirements."

Codes and specs

Upgradation of existing codes and specs can play a vital role in widespread use of latest technologies. It will be remembered that till the early 90s, we never used vibratory compactors. The upgradation of specs and guidelines, and insistence on its implementation has brought a sea change in the quality of the road being constructed. Similar is the case with the quality of aggregates used in road construction. This is a sector that is growing well.

According to Blesson, the existing regulations which are very old, need to be updated. He observes, "As in many countries, the original adopted codes and specifications were based on old British or American standards but with the vast improvement in pavement designs over the last decade or more, we are of the view that much of these codes and specifications will need a renewal. By doing so, it will also aid the development of Indian infrastructure in the 21st century and beyond." He further adds, "As experienced by many countries, the process of improvement is a long and winding road. Hence, in order to allow for widespread acceptance of intelligent compaction, Bomag has always worked closely with customers and delivered products to meet their challenges. We continue to educate contractors, consultants and invite customers to live demos where they can have first-hand experience and verify the results."

Nitin provides another angle. According to him, our existing codes and specs are good enough to make a good road, provided we follow them. He says, "Through the intelligent compaction system, we can achieve desired uniform density in every corner of the compaction bed. At Atlas Copco Dynapac, we always try to promote the most advanced technology and processes which benefit our customers. The intelligent compaction system is a foolproof system to achieve the highest level of compaction."

Demand-supply

Speaking about the demand-supply scenario for the compactors/rollers Ramachandran Nandagopal, Chief Executive Officer, Construction Equipment Business, Greaves Cotton, had this to say, "In the overall market for compaction equipment, soil compactors and heavy tandem rollers bag the biggest share. In the last six months, the average market size was about 230 to 240 machines per month; annually, it is pegged at about 2,500 machines for the last few years. But in April-May, we saw a dip of close to 35 per cent, on a month-on-month basis. That was a pretty radical kind of dip. I think the best was about 3,000 machines, a couple of years ago."

He adds that today, everybody knows that the road or highway construction segment is not doing too well. Major national highways road contracts are not being awarded nor are the contractors willing to bid; there are issues of financing, land acquisition and funding. So the whole segment is in turmoil and to add salt to the wound, there are no major greenfield projects, which are what really drive the demand for these machines. As far as the present situation goes, rural and state highways and urban road renewal are where the demand rests right now. Otherwise, there is hardly any major national highway project going on. But when it comes to rural road construction, the kind of machinery specifications that apply to national highways don't apply here. For rural roads, one could use compactors of any kind of specification; you will even find static rollers being used."

Muralidharan says that in the fourth quarter of 2012 and in early 2013, there was an improvement in the market for compactors, the levels coming back to those of 2010.

Says Anil Bhatia, Director Sales and Marketing, Case New Holland Construction Equipment India, "The growth of this sector is interlinked with the growth of the Indian economy and indirectly, with the growth of infrastructure. Factors like slow land approvals, high interest rates, a weak rupee and the slowdown in the mining industry have affected the market, which registered an almost flat growth over 2012. There is huge growth potential for compactors in an India that is developing a lot in terms of infrastructure. While the construction equipment market looks challenging in the short term due to policy paralysis at the executive level of the government, the medium to long-term growth story of this industry seems intact."

ADVANTAGES OF IC

• Higher compaction without aggregate crushing
• Uniform compaction due to continuous adjustment of compaction output
• Problem-free results on edges and joints
• Ideal for bridge deck surfacing and compaction close to vibration-sensitive buildings, as with oscillation
• Soft spots are detected and can be corrected during rolling operations
• The number of passes/unwanted passes is reduced, directly reducing fuel consumption
• Fewer contractors have the luxury of a veteran roller operator who will get it right

"IC efficiencies ensure time, cost and fuel savings."

IC rollers are able to compact greater amounts of pavement with fewer passes than the traditional static rollers, sometimes in a much shorter time. However, greater acceptance of intelligent compaction systems has to come from the contractor fraternity, says Divakar Marri, Head - Corporate Planning & PMO, Ramky Infrastructure. Excerpts from the interview.

Are there any specific reasons for adopting IC technology?
Performance behaviour and cost-savings of IC technology fitted compactors are not yet known in detail. On the other hand, a greater acceptance of intelligent compaction systems has to come from the contractor fraternity, which has to educate itself and get to understand the advantages this technology offers.

Are you using compactors incorporated with any control technologies?
We are currently not using compactors incorporated with this control technology but given the advantages, we will definitely try to make it part of our equipment in the near future.

How do you address the issue of a dearth of skilled and well-trained operators for compactors with IC technology?
There are several factors that affect pavement performance. One of the challenges in the Indian context is the lack of trained operators. However, the fact remains that just because an experienced operator is in charge, it does not really translate into better quality roads or savings. Moreover, adding digital compaction systems to the mix can give a totally different picture. Once incorporated into road compactors, they then make things a lot easier for the operator and there wouldn't be much of a need for contractual obligation.

Have our road construction practices/methodologies/design mixes come of age to adopt this technology?
As specifications for road-building becomes more sophisticated and with project sizes also get larger by the day, road contractors today are faced with some stiff challenges. Given the challenges of lowering project costs, environmental protection and still obtaining the desired results, I think contractors are looking at various technologies to bail them out of a tight situation.

"We will explore compactors with control technologies"

Compactors with IC technology are still nascent and there is a lack of adequate knowledge among engineers. However, we are optimistic that it shall prove to be cost-effective in due course, says Sudhir R Hoshing, CEO (Roads), Reliance Infrastructure. Excerpts from the interview.

What are the major factors influencing the selection of compaction equipment?
In addition to the primary criterion of meeting MoRTH specifications, the major factors influencing the selection of compaction equipment are improved density, increased productivity, depth of compaction, minimum consumption of fuel and ease of operation.

How do you look at the concept of intelligent compaction?
Intelligent compaction is, no doubt, a technological innovation with several advantages over conventional compaction technologies. However, it being still at a nascent stage suffers from lack of adequate knowledge among engineers and is costlier than conventional compactors.

Has Reliance made use of IC technology?
Not yet. IC technology being in a nascent stage and the dearth of skilled engineers who can operate such technology and the high cost are some of the reasons why we haven't started using such compactors.

What are your views on the existing codes and specs?
The existing codes address the provision of HMP and pavers but they do require upgradation if compactors with IC technology have to be promoted.

Have our road construction practices/methodologies/design mixes come of age to adopt this technology?
Yes, our roads construction practices/ methodologies/ design mixes have come of age with the use of HMP and sensor pavers and can conveniently adopt this technology. Even lenders are now insisting on the use of environment-friendly construction methodologies.

How can segregation be minimised?
We are adopting refusal density in the mix design, using mechanised pavers for WMM and sensor pavers for bituminous layers to achieve the desired homogeneity of air void distribution.