New technology in road building

By Chris Sleight14 November 2012

Asphalt contractor AVR chose a Cat milling machine, paver and compactor to repair a 350 m long, 12 m

Asphalt contractor AVR chose a Cat milling machine, paver and compactor to repair a 350 m long, 12 m wide bus lane in Florence in just one day.

Like other types of equipment, road building machines are being updated with the latest generation of Stage IIB/Tier 4 Interim engines to meet new exhaust emission regulations in Europe and North America. As part of the changes required by these laws, manufacturers are taking the opportunity to update other aspects of machine design, including the control systems. In many cases there is more automation going onto machines, which should help contractors configure equipment quicker and then pave faster and more accurately.

A prime example is the new GOMACO G+ Connect system, a new CAN-based control system for the hydraulic and electronic systems on its concrete paving machines. The company says the closed-loop system between the paver’s valves and various sensors means unparalleled accuracy, with feedback from sensors making for tighter, faster, and more accurate machine corrections.

The hardware includes simple but durable dials and push buttons for machine control along with a 6.5 in (165 mm) flat-panel, anti-glare display screen, which can be viewed at the operator station, or at ground level. It has been programmed to operate in most of the world’s major languages to accommodate the customer’s choices.

Technology shifts

“After we introduced the G+ system, there was an explosion in unforeseen control technology shifts. Our customers, our engineering staff, and our service personnel kept saying, if it can do this, can we make it do that? And our controls team would say, yes,” Kevin Klein, GOMACO’s vice president of engineering/research and development, said. “The majority of the breakthrough innovations for mainline paving have come about since its introduction on our smaller paver in 2010. What we have is a living control system that will continuously grow with our ability to change, improve and enhance the system and the G+ Connect network in-house.”

As well as controlling the paver, the software, which was designed in-house by GOMACO, can also handle accessories such as 3D stringless machine control systems transverse bar inserters (TBI), power transition adjustors (PTA) and GOMACO Smoothness Indicators (GSI), among others. The system can also log machine performance and other parameters – speed and distance measurements for example.

Stringless control is a technology GOMACO pioneered in the concrete paving sector with instrument specialist Leica. It is a technology that is now being adopted by other manufacturers in the segment.

Power Curbers, for example, now offers stringless pouring technology on its 5700-C curb & gutter machine, and the company reports good results, with contractors saving on set up time and finding great accuracy in the placing curb and gutter.

The Power Curbers system features a digital control unit from Moba which can be used with 3D or GPS controllers from a variety different suppliers. Leica and Topcon are the current choices for stringless control. “It was essential from day one to build a system that allowed the contractor to choose the system they were comfortable using,” said Power Curbers vice president for sales & marketing, Stephen Bullock.

New from Guntert & Zimmerman (G&Z) meanwhile is the S850SL, a mid-sized slipform paver with swing legs, featuring the Accu Steer system familiar to users of the S600 paver.

Accu Steer consists of slew drives mounted on top of the crawler track yokes that are used to steer the tracks, rather than steering cylinders. This allows the operator to independently rotate the tracks almost a full circle, providing exceptional on site manoeuvrability and rapid swing leg relocation for paving and transport without the need to re-pin steering cylinders.
Easy adjustments

Working in tandem with Accu Steer, G&Z’s Smart Leg system allows the operator to adjust the swing leg angle on the go while automatically keeping the crawler track straight ahead. This offers a lot of flexibility for the contractor to manoeuvre around obstacles – fire hydrants, airport runway lights etc. – without stopping to make a mechanical swing leg adjustment. The system also helps speed up the process of preparing the paver for transportation.
G&Z describes the S850SL is an “All-Purpose” mid-size paver, for city streets, secondary roads, highway and airport paving, ramps as well as canal lining applications. It has a normal paving width of 3.66 m to 7.92 m.

In the asphalt sector meanwhile, Roadtec is now offering remote diagnostics on many of its models, initially its latest Tier 4 Interim-engined milling machines. The systems allows the monitoring of fuel consumption, engine codes and many other performance and functional data including alarms, starts, cutter function, water, conveyor speeds, propel functions, load control, hydraulics and much more.

This gives the owner real time-data that can be used to make operation as efficient as possible. The remote system can also interface with Moba grade and slope controls and gives unsurpassed remote control over certain functions on these systems.

As well as setting the system to send e-mail alerts if certain problems arise, Roadtec’s diagnostics also give the owner the ability to locate the machine via GPS.

And it is not just in the paving and milling sectors where technology is changing. In the compaction sector Dynapac’s new mid-sized single drum compactors, the CA2500, CA2800, CA3500 and CA4000, feature some of the same innovative thinking that was seen on the larger CA5000, CA6000 and CA6500.

One aspect of this is Dynapac’s ‘mission control’ systems, which are designed to enable users to control the entire project in three steps. Preparation and planning is carried out with the Dynapac Comp Base software, performance is logged with the on-board Compaction Meter and the results analysed using the Dynapac Compaction Analyzer (DCA).

The rollers are available with Stage IIIA or IIIB engines, depending on the country they will be used in, but both versions have fuel saving systems that match engine revs to the load on the power system from the machine. The CA series can also be equipped with a Sustainability Package featuring an rpm management system, biodegradable fill-for-life hydraulic fluid, 50 hours service kit, electrical engine block heater and working lights with LED lamps.

The air-conditioned cabs have a spin-around seat, steering module and display cluster, which allows movement of up to 180° without stress to the neck or body. Safety functions include Electronic Drive Control with a ‘quick brake’ function, which shortens braking distances if the lever is moved very fast, and a tilt indicator. Loss of traction, even in the toughest conditions, is swiftly counteracted by an easy-to-use toggling gear shifting system, or with an optional anti-spin system.

Another interesting feature is Dynapac’s Automatic Bouncing Control, which prevents damage and prolongs the lifetime of the roller by eliminating drum double jump, or over-compacting – an action that can destroy components in the machine. Available as an option is a speed limiter to avoid compacting at too high speed, which saves money in the long term.

In action

Contractor Matthäi relied on pavers from Vögele to place the surface course on the new stretch of the B 442 Federal road near Eimbeckhausen, Germany, a 4 km project comprising three lanes, two passing places and two bridges.

The road was designed as a bypass to the small town of Eimbeckhausen near Hanover, which was seeing as many as 14,000 vehicles per day drive through it, with at times almost a fifth being heavy goods vehicles. These vehicles can now use the new road, which has one lane in either direction, with a third lane in places to aid overtaking.

A consortium consisting of Matthäi Bauunternehmen. Langenhagen and Johann Bunte Bauunternehmung, was awarded the contract for the road works and Matthäi decided to exclusively rely on Vögele pavers because of the exacting nature of the work. For the final 30 mm of stone mastic asphalt (SMA) wearing course, the company used two and sometimes three pavers, laying material “hot on hot”. This technique has emerged in the last few years and has been shown to speed up the paving process as well as improve the final quality of the wearing course.

Most of the asphalt work was undertaken by a Super 1900-2 and a Super 1800-2, both fitted with the TP1 version of the AB 500 extending screed. Bolt-on extensions were fitted for a maximum pave width of 6.5m allowing widths of both 11.5 m and
12.5 m to be paved without time-consuming conversions. A Super 1303‑2 wheeled machine was also used for the passing areas.

Precise grade and slope control were achieved using a Big MultiPlex Ski fitted with sonic sensors, which fed into the on-board Niveltronic Plus automated system for grade and slope control. According to site manager Jörg Gattkowski, this allowed the company to achieve 4 mm accuracy. “Layer thickness, compaction and bond of layers – everything was perfect. We are totally satisfied with the finished pavement,” he said.

Maintenance of roads in historic districts is a challenge for communities around the world, where the need to upgrade infrastructure has to be balanced against the disruption this work can generate. The city of Florence in Italy had to contend with this balancing act when it came to repair the deteriorating roads in its District 5 in the midst of historical surroundings.

The city gave Italian paving contractor AVR, complete control of street repairs in District 5, initially for four months, but this was subsequently extended to six months. AVR monitored the road conditions in a variety of ways, identifying hotspots and creating a call centre where staff, police of local officials could report potholes or other obstacles. The most critical of these had to be remedied in 45 minutes, while all had to be addressed in three working days.

One District 5 street, Viale Corsica quickly became a priority project, where resurfacing, rather than patching was required urgently. The most pressing repairs were needed in the bus lane and the work had to be completed fast in order to cause minimal disruption to commuters, while the adjacent traffic lane had to remain open.

AVR chose the Cat PM200 milling machine to remove the existing damaged surface, the Cat AP600D asphalt paver to lay the new surface and a Cat CD54 tandem roller for compaction.

“This contract was not particularly difficult from a technical point of view, but posed some problems because we had to work on the congested road at peak times whilst having to leave one lane open,” said Lorenzo Porciani, AVR Manager. “We milled and rebuilt 40 mm of mat, over a length of about 350 m and width of 12 m.”
He continued, “Thanks to the high productivity of the Cat PM200 and the excellent qualities of paving and compaction of the AP600D and CD54, we finished in a day, and erected the road signs the following day,” Mr Porciani said.

And the wider scope of the work has proven to be a success for both AVR and the city of Florence. In six months more than 5,000 potholes were filled in District 5, including 143 emergency patches. In addition, more than 84 milling and repaving operations took place in 20 different district streets.

Improving productivity

The influx of new technology into the sector, combined with new systems and ways of working illustrate how contractors can save money by working more efficiently, which often pleases their clients too.

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