Infrastructure investment

Declining investment in roadinfrastructure is Europe is putting thousands of jobs at risk and threatening the welfare model, according to a report published by the European Union Road Federation earlier this year. The Socio-economic benefits of roads in Europe report claims that roads in Europe contribute as much as 20% to GDP but average investment levels in Europe have dropped to less than 1% of GDP.

Nonetheless, construction of new motorways is booming in the new EU member states, thanks partly to access to alternative funding routes from the various investment banks and EU grants. In Western Europe new road construction is limited and the focus is on the need for maintenance and the challenge is finding techniques that are efficient, cost effective and cause minimal disruption to traffic flow.

Current research that is being co-ordinated by the UK’s University of Sheffield is aiming to find road construction solutions which not only cut energy consumption but also construction costs and time. The research, which is focusing on steel fibre reinforced concrete pavements, is being funded by the European Union’s Framework Programme 6 and involves nine organisations from across Europe.

According to the University of Sheffield, the techniques being evaluated could cut costs by up to -20%, construction time by -15% and energy consumption by around -40%. Project co-ordinator Professor Kypros Pilakoutas expects the research to result in development of use of the steel fibres that can be extracted from waste tyres.

Recycled Benefits

The rising cost of raw materials such as oil and aggregates means that asphalt recycling techniques are also coming increasingly under the spotlight. Methods vary around the world, but most were pioneered on minor roads and are now being accepted as a viable option for rehabilitating major roads. The growing acceptance now includes successful use on a busy motorway in Athens, Greece.

“The Korinthos Highway near Athens is used by up to 100000 vehicles a day, 20% of which are heavy goods vehicles,” said Dave Collings senior partner of South Africa-based consultant Loudon International, which provided recycling design advice to main contractor Aktor. “Tests showed that the failures in the road surface were caused by variations in the road’s cement treated base but given the volume of traffic using the route, full depth reconstruction was not possible.”

Aktor, working on a design and build basis, carried out the work on the 21 km section in four phases under lane closures. The site team used a Wirtgen WR 2500 S cold recycling machine to pulverise the existing surface to a maximum depth of 300 mm and mix it with cement and foamed bitumen. Following compaction with both drum and pneumatic rollers, the recycled surface was overlain with a new binder and surface course.

Use of recycling on the Athens motorway saved significant volumes of virgin aggregates and also reduced the amount of material that needed to be taken off site during the project. “The Greek national highway authority is very pleased with the result and is looking at using the same techniques on other motorways,” said Mr Collings.

Maintenance Matters

Maximising service life and reducing the need for future maintenance is also the focus of some of the latest innovations in the road construction sector. However, these new techniques are not only improving the quality of the finished surface but are also helping to speed up the construction phase.

One of the latest developments in the paving sector is ‘hot-on-hot’ asphalt pavers and both Dynapac and Vögele offer machines which are capable of laying two different layers of asphalt in one go.

According to Dynapac, its F300C/S - AM300 Compact Asphalt Paver not only speeds up the surfacing phase of the work but can also double the service life of the new pavement. In addition to a longer service life, Dynapac has also said that surfaces laid by the paver are up to +70% more resistant to deformation and uses less material than conventional pavers. (CE visited a motorway resurfacing project in Germany last month to see the machine in action and full details can be found in the site report on page 62.)

The design of Vögele’s ‘Inline Pave’ system is based on the company’s conventional pavers and, Vögele claims this opens the method up to a wider circle because it doesn’t call for high capital investment.

Like the Dynapac system, the Vögele Inline Pavers use a compacting screed to compact the lower binder course as it is laid and is followed immediately after by the laying of the surface course over the top. Unlike the Dynapac machine, the Vögele Inline system ‘links’ two modified conventional pavers together.

Vögele’s Inline Pave system can surface roads up to 8,5 m wide in one pass. The paving train consists of a Super 2100-2 IP paver, which is fitted with an AB 600 IP high compaction screed, to place the binder course with a Super 1600-2 or Super 1800-2 paver to lay the surface course and an MT 1000 IP mobile feeder to ensure a continuous supply of asphalt.

According to Vögele, the ‘hot-on-hot’ technique retains more heat than conventional single layer surfacing which allows it to be used in colder or wetter conditions than is normally possible. Vögele also claims that asphalt laid ‘hot-on-hot’ can be laid thinner to give the same performance characteristics than when using conventional surfacing methods. The ‘hot-on-hot’ layers can be laid at 15 to 20 mm thick, instead of 35 to 40 mm, which reduces the amount of raw materials needed to construct the new pavement.

But while faster surfacing reduces the impact of the work on traffic, getting the compaction right is essential to achieve the design characteristics.

“Modern asphalts need careful compaction to ensure they achieve the right properties,” said Hamm product manager Ralf Schröder. “Our HD rollers were developed specially for use with open/porous asphalt, which must not be over compacted or it loses texture that allows it to drain surface water. Porous asphalt needs a large drum with a low static load but high vibration to achieve the right level of compaction and the HD series has been developed to meet this demand.”

According to Mr Schröder, one of the biggest development in the compaction sector in recent years has been oscillation technology. “Thin asphalt layers are best compacted using static loads or oscillation,” he said. “Use of vibration on thin asphalts usually results in cracking.”

Hamm has carried out extensive testing with its oscillating rollers and thin asphalt layers to gain a better understanding of compaction control. The company is now working on developing the Hamm Compaction Quality (HCQ) system, which was originally developed for sub-base compaction, for use with asphalt.

“In its standard format, the HCQ measures stiffness of the sub-base and combines it with GPS data to provide accurate information on the compaction and minimise the number of passes needed,” said Mr Schröder. “Now we want to bring this technology to the asphalt sector but it’s not as simple as measuring stiffness, because the stiffness of asphalt is influenced by the ambient temperature, temperature of the material, frequency of the compaction and so on.

“We are currently testing a prototype system and new software, which we hope to be able to launch during 2007. Last year we used the system over a 20000 m² area at our factory and undertook 8000 pavement quality indicator tests over the area to evaluate the results. Now we’re ready to test it on a live job site and we are currently looking for a suitable project.”

Accuracy is also a vital ingredient in modern road construction and the sector is starting to benefit from the GPS technology, which has already revolutionised the earthmoving industry. GPS machine control is already being used on pavers to add accuracy to surfacing work but systems are now also being developed for concrete pavers.

Leica has been working with Gomaco to develop its PaveSmart 3D system for curb and gutter paving applications and, according to Leica, it is the world’s first fully automated track grade and steer control system for concrete paving equipment. The system, which is based on a new modular 3D software platform, allows contractors to upload the project to the machine and pave without any time consuming setting out.

GPS systems are also being added to rollers to allow operators to track compaction passes. Bomag’s system combines its Variocontrol and its BCM05 compaction measuring system with a GPS receiver to provide co-ordinate values accurate to 25 mm. The system is linked to an on site GPS reference station, which enables to operator to view the compaction in real-time and adjust the roller accordingly.

The information can also be transferred to the construction office and a graphical display show the areas where the compaction has been achieved in green, while areas which require further work are displayed in red.

New Machines

The European Stage IIIA emissions regulations for engines in the 130 to 560 kW power bracket came into force in January 2006. The change resulted in a wave of new machine launches in the road construction sector earlier this year and many of these were displayed for the first time at the Intermat exhibition in Paris, France. Nonetheless, manufacturers have since added other machines to their product lines and some are beginning to talk about the equipment which will be on display at the 2007 Bauma show in Munich, Germany.

Ingersoll Rand’s latest product launch marks the company’s entry into a new area of the road construction market and, according to Ingersoll Rand road development president Gary Michael, the launch gives the company “a full complement of products”. The company has launched two milling machines - The MT-2000, which offers a 2 m milling width, and the MW-500 with a 500 mm working width.

Wirtgen has also added to its milling machine range with the addition of the W 100 F, which offers +20% more power than the previous model as well as a more ergonomic, easier to use design. The new W 100 F offers standard working width of between 1 and 1.3 m but can also be used with Wirtgen’s Flexible Cutter System to give working widths of 0.3 to 1 m. The design concept on the W 100 F will also feature on the new W 100 and W 60, which will be launched at Bauma next year.

Paving The Way

Bauma will also be the launch pad for Bomag branded pavers, which are currently sold by Bomag’s sister company Marini. According to Bomag head of product management Lutz Stallgies, Fayat Group-owned Bomag is not just taking over the paver range from Marini but is redeveloping the machines to improve the operation and performance.

As well as Vögele’s new dual asphalt paver, the company has also added four other ‘conventional’ pavers to its line up. The new models follow on from the launch of the other ‘dash two’ pavers - the Super 1900-2 and 2100-2 - at Intermat and also feature the ErgoPlus design, which offers better controls and cab for the operator. Also new on all the models is the Niveltronic Plus Automated Grade and Slope Control.

The Super 1603-2 and Super 1803-2 wheeled pavers offer paving widths of up to 7 m and 8 m, respectively, while the tracker models, the Super 1600-2 and Super 1800-2, can pave widths of up to 8 m and 10m, respectively. Vögele is expected to launch another four models at Bauma 2007 to complete the range.

Ingersoll Rand has also added to it paver range with the launch of the PF-6110 tracked paver and PF-6160 and PF-6170 wheeled pavers. All three have a 13,1 tonne hopper capacity and are powered by 153 kW Stage IIIA compliant Cummins engines to give paving speed of 89,3 m/min for the wheeled models and 74,9 m/min for the tracked version.

The new models also feature a hydrostatic direct-traction drive system, which according to Ingersoll Rand, eliminates around 70% of the mechanical drive train components used on previous models and will help to reduce maintenance costs.

Compaction

Recent additions to Bomag’s product line include a 22 tonne single drum roller, the BW 222 D-4, which is manufactured to meet the specific needs of the Chinese domestic market. “It is impossible to cover the whole world with one product line,” said Mr Stallgies. “At Bomag, we try to develop a platform which is then specified using common parts to suit the demands of each country.”

Hamm is also planning to show new compaction products at next year’s Bauma exhibition. The company launched the first three models in its small HD range, with operating weights of between 1.5 and 4 tonnes, at Intermat but has said that another three will be added to expand the range.

Bomag plans to introduce four new light reversible plate models at next year’s Bauma exhibition, which will extend the range to seven machines in the 120 to 700 kg weight class. The new machines are likely to include measuring technology, which will give operators a display of the increase in bearing capacity of the material they are compacting.

Further Growth?

New emissions regulations have helped to drive development of new road construction equipment in the last 12 months and a number of manufacturers are already talking about launching new machines at Bauma 2007. But the need for more efficient and cost effective techniques is likely to stimulate further innovation in the sector over the next few years.

The current growth in infrastructure investment in Eastern Europe is already helping to stimulate road construction equipment sales and this is likely to continue growing. Mr Stallgies told CE, “The road construction market is booming everywhere at the moment - mainly due to renewal of rental fleets - but sales in the UK and Eastern Europe are particularly strong at the moment.

“In the early 1990s most of the equipment sold into Eastern Europe was used but now the demand for new machines is rising. The pattern we are seeing is very similar to that seen in East Germany 10 years ago, with high investment for five years in major transport links and then investment moves onto smaller schemes.

“The current boom across Europe is expected to continue in 2007 and we are expecting the rising demand in Eastern Europe to continue for another two to three years.”