Technological advantages in road building

There was a time when building a road involved laying material, compacting it and hoping that at the end of the day it met the client’s specifications.

The problem with that approach is the uncertainty for the contractor throughout the project. Better to know as you go along whether the road is going to pass muster, and better still to be able to document this as you go.

This is something that many types of road building equipment can deliver, thanks to various on-board and add-on technologies. Many offer the further advantage that they can cut out unnecessary tasks and improve efficiency in other ways for the contractor.

For example, when the New York State Thruway Authority wanted to experiment with unbonded concrete overlays it chose a 5 mile (8 km), four-lane section of Interstate 90 near Hamburg as the test section. Surianello General Concrete based in Buffalo, New York, US won the bid to pave the 9" (229 mm) thick concrete overlay.

The age and the design of the original roadway posed a challenge from the start. It was built in the 1950s and didn’t conform to current geometry requirements. The road’s overlay also meant there would be challenges in setting up a traditional stringline.

The answer to both issues was a GOMACO four-track GHP-2800 paver equipped with a new independent IDBI dowel bar inserter and a Leica Geosystems 3D stringless guidance system to control the machine. As both systems were new to Surianello, the company took part in training and a test pour at their headquarters, aided by members of GOMACO’s 3D team, service department, and an instructor from GOMACO University.

“We did a 150 foot (45.7 m) test pour at our facilities in Buffalo where we trained our operators on the dowel bar inserter and the stringless,” said company president Frank Surianello. “The hands-on experience allowed us to get our ducks in a row so when we mobilised for the actual project, everyone knew their job and we could hit the ground running.”

On the job itself, the GHP-2800 paved 25 feet (7.6 m) wide and 9" (229 mm) thick. Every 15 feet (4.6 m) the IDBI placed 25 dowel bars for transverse joints.

“We had 1000 joints on the project and we did not find one bar that was out of place,” Mr Surianello said. “The GOMACO service representative did a great job setting up the paver and my guys really got tuned into it.”

Real-time pavement smoothness behind the GHP-2800 was monitored by two paver-mounted GOMACO Smoothness Indicator (GSI) units.
“We really found some interesting things using the GSI and getting real-time smoothness numbers and what affects the smoothness coming out the back of that paver. It was just incredible,” said Mr Surianello.

Paving production averaged around 2,600 feet (792 m) per day, and the GSI showed the company it was reaching maximum smoothness results at that speed.

“I’ve had some industry feedback stating straight out that this is the smoothest concrete pavement that anybody has ever ridden on in New York,” Mr Surianello proudly said. “And these are blacktop guys saying it!”

Machine control advantage

In a different application of similar technology, TACC Construction prepared an 800-acre (324 Ha) site in Oakville, near Toronto, Canada ahead of a development by house builder Mattamy Homes. The work involved laying out the final road network, for which TACC used a GPS machine control system on a curb & gutter slipform paver.

“We’re comfortable running our Topcon 3D-MC2 on our Cat dozers that were used on the site,” said Frank Saracino, road superintendent for TACC. “What was new for us was using Topcon Millimetre GPS machine control on our Power Curber 5700-C. We like the Power Curber because it’s compact and designed for tight radius jobs, which made it appropriate for the subdivision with its meandering roads and cul-de-sacs. It was pretty amazing to see how efficient the Millimetre GPS Topcon system made the curber. We eliminated stringlines which saved us time, labour, concrete waste, and it’s much more precise. The technology made the Power Curber at least one and a half to two times quicker than using traditional methods.”

There was 11 km of curbs laid throughout the development. Mattamy Homes hired its own engineering firm to create the original site plan that TACC adapted for use with the Topcon GPS machine control systems by creating its own 3D digital model.

TACC Construction faced three production deadlines with this project. “We beat each deadline by two to three days, which is pretty impressive considering how tight they were,” Mr Saracino said. “This was our first project where we were totally integrated with technology on our earthmoving and road construction. The technology provided seamless transition from task to task.”

Ramp challenges

Meanwhile in Iowa, US earlier this year an unseasonably wet spring presented big challenges for the construction of a highway ramp on the I-80 highway. However, contractor McAninch was able to tackle the project with the help of Caterpillar’s Machine Drive Power (MDP) compaction measurement technology.

The system evaluates rolling resistance to provide an indication of soil stiffness and load-bearing strength. On this job it McAninch said it improved productivity by enabling crews to make fewer passes and it helped them avoid quality control problems that could have resulted in re-work and lost time.

The operator viewed real-time results on the Cat CS74B soil compactor’s in-cab monitor. This was fitted with Cat Compaction Control, a compaction measurement tool that includes MDP.

The monitor was configured to display green when the area had been covered and compaction targets met, and red for problem areas.

For example, a problem was flagged when the display was still red after two passes over a particular area. Given the site conditions, this indicated lots of heavy clay and probably too much moisture.
This was tackled by turning the soil with a disker (harrow) and leaving it to dry out, before making another pass with the CS74B. This time the screen turned green.

Failing to locate the problem and take action would have been costly. The section might have failed testing and required time-consuming re-work. It also could have gone unnoticed and led to premature failure.

A second benefit was the dramatic productivity improvement. Traditional method specifications would have required eight passes on this scheme. McAninch crews – with the help of MDP – were able to verify that only two or three passes were enough to reach the target.

Transylvanian motorway

The construction of the 588 km A3 – the Transylvanian motorway – was given the go-ahead in 2004. Once completed in 2017 it will link the Romanian capital Bucharest with the Hungarian and the M4 motorway.

One of the consortiums winning work on the 62km section from Bucharest to was Spedition UMB /Pa&Co International/Euroconstruct’98/Com-Axa. Spedition UMB opted for Wirtgen Group equipment and solutions for all construction phases, from the foundation and soil stabilisation, paving and compaction of asphalt, to construction of the adjoining concrete gutters and curbs.

Six 20 tonne Hamm 3520 vibratory rollers compacted the soil in two groups of three machines operating in echelon. They were equipped with HCQ meters to check the degree of compaction in real time and indicate any corrections that may be necessary.

They were also equipped with the Hammtronic microprocessor control system to optimise machine functions, ensuring economical use of consumables, optimum compaction results and maximum safety.
Soil stabilisation was carried out in-situ by a machine set comprising an SW 16 TA binding agent spreader, Wirtgen WR 2500 S recycler and Hamm 3518 compactor with an operating weight of 18 tonnes.

UMB Spedition used two Vögele pavers for the asphalt paving work, a Vögele Super 1900-2 with AB 600-2 TV screed with a pave width of 7.5 m, and a Vögele Super 2100-2 equipped with the same screed, but extended to a maximum pave width of 9 m.

The first asphalt layer was levelled with the aid of Vögele Niveltronic Plus. This automatic grade and slope control system allows the grade to be controlled across the entire section by tracking a specific reference.

A Big-MultiPlex Ski was also used for the additional layers, and virtual scanning with three ultrasonic sensors meant that it was not necessary to set up stringlines. This eliminated both the need to constantly reposition stringlines and problems resulting from incorrect positioning choices.

Several Hamm GRW 15 pneumatic tyred rollers and DV 90 VV tandem oscillation rollers were employed for the final
compaction stage.

A key feature of the DV 90 VV rollers and Hammtronic management system is the way they continually adjust speed and oscillation frequency to the surface being compacted.

Finally, adjoining concrete elements – gutters and curbs etc. – were cast with a Wirtgen SP 250 slipform paver. For this application, UMB Spedition adjusted the configuration so that the SP 250 could lay down both the sand base course and the concrete in the specified profile. This resulted in a substantial increase in productivity and a high-quality profile.

Compaction strategy

With a similar use of technology, German contractor Heim KG resurfaced the blacktop on a 3.5 km long, 15 m wide northbound section of the A7 near Altenstadt, Germany in just twelve weeks, despite difficult weather conditions.

Heim used two Ammann pneumatic tyred rollers and five tandem rollers to compact the base layer and binder course and a further seven Ammann tandem vibration machines for top layer. Equipment rental company Nagel Mietservice and the Ammann’s own Hire Pool service provided the machines on a short-term basis.

Dietmar Nille, Heim’s senior construction manager at the A7 construction site said, “The greatest challenge facing the A7 project was the tight schedule. We had to develop this elaborate machine strategy to ensure adherence to the schedule. That is why I got our long-standing partners, Ammann and Nagel, on board during the bidding phase. Our compaction strategy gave us not only the advantage of entering the bidding phase with a very good price-performance ratio, but it also gave us a time buffer.”

As a result, the base layer, binder course and topping were installed and compacted over the entire length of the construction site in just twelve working days. A key aid to the fast progress was the Ammann ACE Navigator system fitted to the rollers, which measures the temperature of the asphalt as the roller crosses and shows the number of passes in each lane. The system regulates amplitude and frequency continuously and steplessly based on the asphalt temperature.

In a different type of asphalt project, Peab Asfalt has used a 9.4 tonne Dynapac CC334HF split drum roller with equipped with the compaction control system and Dynapac’s Compaction Analyzer Asphalt (DCA- A) to lay 25,000 m2 of material at a port project in Karlshamn, Sweden.

The top layer of asphalt is porous, and will later be filled with a concrete slurry to create a stable and rut-resistant surface known generically as grouted macadam. The area will be used to handle containerised freight and other goods.

Helping hand

One of Peab’s operators said of the DCA-A system, “It is very helpful for keeping track of where I have been, especially on a big job area like this. Not only does it help me not miss any areas/passes before they have gone too cold, but the temperature meter itself helps with the cold rolling because I can keep track of when the asphalt is cold enough for static rolling in order to get rid of the marks in the mat.”

Clark Construction, based in San Antonio, US won the bid to repair and resurface a 15-mile (24 km) stretch of U.S. Highway 281 that the Texas Department of Transportation (TxDOT) identified for significant maintenance.

Having milled to a depth of 2" (51 mm) using a Roadtec RX-700 milling machine from its fleet and a newly acquired Roadtec RX-600e milling machine, Clark set about the paving work using its Roadtec SP-200 spray paver.

“The Roadtec SP-200 spray paver has an innovative design that’s been extremely helpful to us,” said Corey S. Clark, director of asphalt and fleet operations for Clark Construction. “On previous jobs we have experienced a significant amount of savings in time, number of employees required, and materials cost.”

Differing from a conventional paver, the machine sprays a tack coat seconds before laying the asphalt mix. The tack coat is designed to ensure a good bond to the existing pavement.

“This is the second SP-200 paver we’ve owned since 2004,” Mr Clark said, “The big benefit for us is the machine provides superior bonding to the existing pavement. The TxDOT inspectors were impressed to see that within seconds of the oil spray that the asphalt was placed.”

He concluded, “I’m happy with the finished results on our Highway 281 project. We achieved a great ride, good quality, and the finished road looks great…and we expect it to last
10-plus years.”

Equipment advantage

Meanwhile Clearspan Technology Middle East has bought a Guntert & Zimmerman (G&Z) S850 concrete slipform paver and used it to complete two fast-track projects for Qatar Airways at Doha International Airport (DIA) in the form of six bay and a two bay apron expansion contracts.

“The schedules were so tight that without our G&Z machinery the programme would not have been possible,” said Joe Sarlak, owner and managing director of Clearspan.

The projects totalled US$ 7 million. The 500m x 138m six bay apron was the first project to tackle while the 132 m x 66 m two bay was the second to be completed. CMTE paved the aprons at 6 m wide with a thickness of 375 mm in alternating lanes and finished with fill-in lanes. “The machine is outstanding; we have experienced no downtime and no mechanical failures,” said Mr Sarlak.

He added, “With the acquisition of our G&Z paver, we can offer an added advantage to project owners who have tight schedules and high quality requirements.”

This all goes to show that investing in new equipment and technology can provide a significant competitive edge for contractors.