Road Building in Al Ain
We drop in on a site employing new tech to its road paving equipment
Green is a word we hear banded about too much at the moment, but the inland city of Al Ain can use it both literally and figuratively, as despite recording the highest temperatures in the UAE the inland oasis enjoys an abundance of fresh vegetation all year round.
On our visit, the city could hardly have been described as ‘hectic’ as little more than a few dusty pick-ups rolled down the palm-lined avenues. However, the government is planning for the future, and so it has decided that traffic will get a boost with the widening of the current four-lane carriageway in and out of the city.
Already work is well underway, though as the project includes a 50km stretch from the Abu Dhabi border and right into the centre of town, where it connects to a new ring road.
The road widening is welcomed, but with so many millions of dirhams being poured into the project, everybody wants to be assured of getting a top job – and the contractors want to be sure of delivering it.
Unlike many desert highways, it isn’t simply a matter of widening a road over dust and sand. In fact the road spans over a number of bridges, which all need substantial engineering work, before passing through the existing road network that skirts the city, resulting in a lot of urban re-planning.
There is a lot to do, and one of the contractors, Mohammed Abdulmoshin Al Kharafi and Sons, has tracked in a lot of heavy equipment. This is by no means a comprehensive list, but on a trip along the worksite we saw lots of excavators, mostly Komatsu PC200s, as well as a number of Cat 966 loaders of various ages and the usual mix of trucks.
At one point various mobile cranes, including a medium-weight Lorain, were gathered, presumably as part of one of the various bridge-widening projects.
Needless to say, for a road building site you’ll also want motor graders, and we saw lots of the ubiquitous Cat 14G and H series roaming the site, as well as a couple of Mitsubishi graders. Over on the ring road site it is Bin Dawish Contracting handling the road building works.
However, it is the road laying kit that we are most interested in looking at. Laying a macadam road is pretty much the same everywhere, but a long straight road designed to be navigated at high speed is particularly sensitive to slight undulations.
You might be familiar with the nagging sensation that you are steering a boat on the sea rather than a car, as it pitches up and down on an apparently flat road.
This is because the top surface is not perfectly smooth – at speed even the slightest wrong grade can make the vehicle pitch like a boat on choppy waters.
Both contractors mentioned have bought technology which will help eliminate this problem. Previously, the site surveyor would have to mark out the land with stakes and twine, while simply knocking the stake in to the ground another ‘notch’ to adjust the elevation.
The paver operator would then have to do his best to keep in line with the wire – and given the speed road contractors were expected to work in the past, it is no wonder there are more than a few rather bumpy main roads around the region.
Getting the top coat right is the most important thing, according to Mickey Hales, general manager for local Topcon dealer TMAG.
“It is critical that you get the smoothness on the final grade, it’s the other layers that should concentrate on the surveyor’s elevation and the thickness of the asphalt” he explained.
“On the last two layers you should concentrate on ride-ability and smoothness. It’s like painting on the final coat.”
The contractors on this project have turned to new technology to help solve this problem. PMV has reported before on how machine control using a mixture of GPS and laser tech can help, but on this occasion, the attention has been turned to the pavers themselves.
On the Bin Darwish site, the Vogel pavers are as wide as you can buy them, yet it is going to take three of them running side by side to lay each carriageway of the new super wide road.
As we went on site, the machines had temporarily stopped – never good while pavers are rolling, but they needed to refill with asphalt. This at least gave us a chance to speak to the site foreman, Noah, who explained that the sonar system had made the operation much faster.
“We think that we cut the amount of time paving by almost half,” he said, adding that the old method of using stakes with wire was incredibly difficult for the operators to follow.
Fitted to the pavers is a series of sensors that each emit an ultrasonic signal that bounces from the ground, telling the machine operator exactly what the road profile is.
To achieve a perfectly smooth road, the operator only needs to simply follow an arrow up or down. This can be used in conjunction with a laser level.
At the Kharafi site, very similar equipment is used. Two extra-wide pavers are both equipped with the sonar guides. A Vogel machine leads the way, flanked on the nearside by an ABG machine (now part of Volvo CE). These machines are making stately, but steady progress over the blacktop as the project advances.
As Hales points out: “You really want to keep these things running for as long as possible – 18 hours a day preferably as stop-starting will put bumps in the road, though the actual run time is going to be determined by the amount of asphalt supplied,” he explained.
Hales said that the technology behind the pavers themselves has remained similar since the concept was invented – after all, the Archimedes screw, central to the paver system, has quite literally, been around since the time of antiquity.
Speaking of which, there is a constant flow of trucks in and out of the job site. These tend to be rigid U-body heavy tipping trucks, and it appeared that most older units were based on Mercedes chassis, while newer looking units were invariably Renault.
A couple of small bowser trucks also came and went from site during our visit – one water truck and one apparently carrying diesel for the site vehicles.
Interestingly, these units were Bedford TKs – a British model which hasn’t been built since 1981, so somebody must have a keen mechanic.
Behind the pavers, no less than four pneumatic tyre rollers are waiting for the surface to stabilise enough in order that they can operate. All the pneumatics we saw are German-made units is Hamm, and like all tyre-rollers the condition of the rubber, right down to the tyre pressures needs to be exact to ensure good compaction.
Also waiting in the wings is a Bomag steel drum finish roller, to ensure a top job.
The other big news in the road roller market is the development of ‘oscillating’ rollers in place of standard vibratory compaction rollers.
These new machines are in demand on road building projects all over the world as the technology allows high compaction performance without producing damaging vibrations. The design also allows the roller to be used on bitumen at lower temperatures than previously possible.
These roadworks to go yet but thanks to modern technology, pavers are able to cover huge distances and provide far better results than ever before.