Building smoother roads
By Chris Sleight09 May 2012
The road building sector is currently taking another leap forward in technology, with the introduction of new Stage IIIB/ Tier 4 Interim engines on pavers, compactors and milling machines leading to new product launches with numerous new features.
This year's new engine emission laws hit diesels with an output from 75 to 130 kW. Combined with last year's laws on
130 kW+ engines, this means all but the smallest pavers, along with rollers from about 9 tonnes and upwards and all sizes of milling machine are up for renewal if they haven't been launched already.
As well as re-powering their machines, manufacturers are taking the opportunity to re-vamp other aspects of machine design, and although the Stage IIIB/Tier 4 Interim engine regulations only apply to Europe and North America, the other improvements and design tweaks that are being made are likely to filter out to machines sold in other parts of the world as time goes on.
Vögele's Dash-3 range of pavers illustrate this point well. On the one hand they feature low emission Stage IIIB engines from Cummins, but other improvements made to the machine to save fuel include a splitter gear box, which disengages the traction, conveyor, auger and compaction hydraulic circuits when the machine is stationary.
An on-demand fan, which provides only the amount of cooling that's required, is another fuel saving feature, as is an energy-optimised tamper drive.
Vögele has further updated its Ergo Plus operator station with a new full-colour, high contrast display, and seats and consoles that are easier to adjust.
But a particularly clever new feature is the 'Auto Set' function, which allows the operator to switch between transport and paving set-ups at the push of a single button. When preparing to move, for example, the system automatically raises the screed and augers and brings in the hopper sides and deflectors. When it's time to lay asphalt again, a single push of the same button resets all the components to the previous working positions.
One of the noticeable improvements on Volvo's new line of pavers meanwhile is the lower noise levels. New machines like the 13 m maximum paving width P8820C ABG and 11 m P7820C ABG offer up to a -50% reduction in noise thanks to the quieter low emission engines, other component improvements and the robust frame design. Lower noise is of course important to both improve the operators' working environment and reduce the annoyance to members of the public.
One of the new features that helps with this noise reduction is the Smart Power mode. This works on the basis that most on most paving jobs the full engine power will not be required, so engine revs are automatically lowered to better match the demand. Volvo says this can cut fuel consumption by as much as -30%.
Dynapac divides its paver range into two streams. The SD series features the electronic control and low emission engines that are required in Europe and North America, while the F-series features simpler electrical systems and is designed for other markets around the world.
Intermat saw the company unveil the latest wheeled versions in both ranges the 2 m to 9 m F2500W, SD2500W and SD2500WS. Both feature a re-worked undercarriage which is now shorter at 6.1 m for a tighter turning radius. A larger 315 litre fuel tank has also been added to increase refill intervals and maintenance has been simplified with the introduction of just two servicing kits that cover the full range of Dynapac wheeled and tracked pavers.
The more sophisticated SD2500W and WS feature a variable displacement pump for the rear wheel drive and Dynapac's 'Add Traxxion' concept for the front drive, which adapts to the tractive effort to the load being applied. This means the paver has enough grip when the hopper is full, but that fuel is saved as it empties.
The SD series also features a new 6.5 in (165 mm) colour display.
Caterpillar's latest pavers, again launched at Intermat, are the AP1000E (wheeled) and AP1055E (tracked) units, which offer paving widths up to 8 m when used with the AS4251C and AS4252C screeds.
An interesting new feature is the Cat Fumes Management System, which the company says removes 92% of the fumes from the auger chamber and conveyor track and directs them away from the operator through the exhaust stack. A similar system was fitted to the Volvo prototype P6110C tracked paver shown at March's World of Asphalt exhibition in Charlotte, US.
On the Volvo machine, the extracted bitumen fumes run out through a pipe that surrounds the exhaust stack, and the company says this is an important safety feature. The new Tier 4 Interim engines use high exhaust temperatures to burn off particulate matter (soot) coming out of the engine, and as a result, the engine exhaust pipe can get very hot. Volvo says that by surrounding the engine exhaust with its fume extraction pipe, it has made its machine safer - with less risk of accidental burns.
Back to Caterpillar's new pavers, and the company has added new tyres and a position sensor on the left steering cylinder to help maintain consistent travel speeds when turning. There are three propulsion and steering modes, the self-explanatory 'Pave' mode, the 'Travel' mode for transportation and the 'Manoeuvre' mode for positioning the machine on site, which allows the AP1055E to rotate within its own footprint.
Two swing-out operator stations, tilting consoles and the low-profile design of the cooling system provide good forward visibility. Caterpillar pavers can be equipped with the Cat Grade and Slope control system as a factory-fitted option. These machine control systems remove irregularities from the surface and control the mat thickness.
For Europe and the US, the AP1055E comes with a Tier 4 Interim/Stage IIIB Cat C7.1 engine. In lesser regulated markets it will be sold with a Tier 3/Stage IIIA Cat C6.6 engine.
Also new from Caterpillar is its smallest paver ever, the AP255E, which weighs in at 4.5 tonnes. The standard paving width range is 1.4 m to 2.6 m, while extensions can take this up to 3.4 m. Central and right-hand side attachments can be added to reduce the paving width to as low as 150 mm for use on trenches, narrow shoulders and footpaths.
The World of Asphalt exhibition also saw Terex display a pre-production version of its CR662RM wheeled asphalt paver. Fitted with a Tier 4 Interim engine, the 10 ft (3 m) class machine also features other upgrades, such as improvements to the controls and new, brighter control screens that are easier to read in direct sunlight.
Roadtec used the show to launch several new machines, again with new low emission engines. As well as its new pavers and milling machines, it says the last few years have seen a big surge in demand for its Shuttle Buggy transfer vehicles.
The latest model is the SB-2500e, which has a hopper capacity of 22.7 tonnes. As well as new conveyors, the unit has more durable wear parts including spreaders and chains. "We expect to see +30% more life out of them, and that's a conservative estimate," said Roadtec marketing manager Eric Baker.
The need for a specialised machine to feed an asphalt paver is not immediately obvious, but Roadtec says there are several significant advantages over the traditional method of trucks tipping asphalt straight into the paver.
First, the Shuttle Buggy provides a way of storing hot asphalt on site. This means trucks are not waiting around on site, so the number of vehicles required can be cut - trucks can unload into the Shuttle Buggy as soon as they reach the paving site, and then return to the plant for more asphalt.
Another important factor is that transfer vehicles can play a big part in improving the final quality of the road. As they deliver the asphalt to the paver, they re-mix it, which evens out the temperature across the material, eliminating any cold areas that might have developed in the asphalt that was on top in the truck.
This means that the asphalt mat which is laid is of an even temperature, which means an even density and a smoother finish.
In the US, among other countries, contractors can earn bonuses if they meet certain smoothness criteria, and Roadtec says this potential pay-off is a key reason for the rise in popularity of their Shuttle Buggies.
The need for a smooth finish of course applies equally to asphalt and concrete, and it is an area where GOMACO has seen a rise in demand. At the start of this year it introduced new hardware and software for its GOMACO Smoothness Indicator (GSI), which can be mounted to pavers.
The new unit is more durable, with a 7 in (178 mm) touch-screen for the operator, connected to the sensor via a single lead. WiFi, Bluetooth and USB connections are also available to help contractors document their work.
The GSI itself provides smoothness readings in real time and displays them on the monitor. It can work over as many as four lanes in a single pass and can provide a number of smoothness indicators such as International Roughness Index (IRI) numbers, the Profile Index (PI) used by California Profilograph methods as well as the GSI number. Data can also be exported for further analysis.
As well as producing these metrics, the system can log the location of bumps or smooth patches and can be set to trigger an alarm should a bump exceed tolerance. As well as the paver-mounted version, the GSI is available as a mobile unit for surveying work.
Although many of the new pavers launched this year are only available in Europe and North America, other technologies that are being introduced will find their way onto machines throughout the world. This gives contractors the opportunity to improve the quality of their work and earn bonuses, as well as document work more fully to guard against liability issues.