And while regulations are en-forced throughout most of Europe, each country can have its own set of rules, which poses potential difficulties for those operating across the continent (see story, p. 30).
Although members of the 27-nation European Union have set their own standards for vehicle size, the EU standard trailer truck specifications — which are measured in meters and metric tons — are about 13.1 feet high and 54.1 feet long and weigh in at almost 88,185 pounds on five axles. In markets such as the United Kingdom, this standard would create a significant issue and has received little welcome.
“Around 80% of the U.K. trailer fleet has a height of [about 13.9 feet] or more,” said Nick Payne of the U.K. Road Haulage Association. “The U.K. [Department for Transport] has been arguing against this move in Brussels [the seat of EU governance], and its position is clear. In the worst-case example, restricting the U.K. trailer fleet to [about 13.1 feet] in height would increase miles traveled by 400 million and create an additional 330,693 tons of CO2 emissions.”
Such a regulation, Payne said, also would cause new trailer demand to fall because fleets could refurbish old trailers to avoid new height restrictions, prejudicing economic carrying of current module sizes. Warehouse configurations would need to be changed at huge cost to cope with the constraints imposed by revised docking heights and modules, he said.
Tractor units would have to meet lower fifth-wheel heights, causing a loss of asset value. Transportation costs in general would increase by more than the proportional reduction in height, i.e., more than 6%, which when combined with fuel and equipment cost escalation would have serious implications for the national economy.
Vehicle height limits have imposed significant restraint upon European vehicle design. Like all European truck manufacturers, the MAN Truck & Bus Group, based in Munich, Germany, has developed several different concept vehicles that attain the best fuel efficiency through aerodynamic improvements.
“Our Concept S, in conjunction with an aerodynamically optimized semi-trailer, is as streamlined as a modern passenger car,” said Holger Koos, head truck designer of MAN Truck & Bus. “We proved it in the wind tunnel, and potential savings in consumption will bring an important step forward toward future CO2-saving goals.”
Trailer manufacturers agree.
“Fuel consumption is the defining topic of the future, and EU-wide regulation of the CO2 emissions for heavy vehicles is currently in discussion, as every liter of diesel saved can reduce carbon emissions by” more than 5.8 pounds, said Paul Avery, managing director for Schmitz Cargobull U.K. Ltd., the U.K. subsidiary of Schmitz Cargo-bull AG, generally considered Europe’s largest trailer builder.
“Fleet operators should remember that basic aerodynamic savings cost nothing, and our advice to address this simply is to adjust the height of the cab’s roof spoiler as precisely as possible, trim weight and reduce frontal area,” Avery said.
“Schmitz Cargobull’s semi-chassis reefer models sit approximately [4 inches] lower than competitor European reefer trailers, while maintaining the same internal working height dimensions,” Avery said. “This reduction in overall height reduces the frontal area of the trailer and improves the vehicle’s aerodynamics.
“Semi-chassis reefers are also, on average, [about 1,100 pounds to about 1,540 pounds] lighter than competitor trailers built on a full chassis. Lighter trailers require less tractive effort which, again, results in fuel savings,” he said.
“One of our customers, a big supermarket fleet, [which] prefers to remain anonymous for the time being, has been comparing the fuel consumption characteristics of various temperature-controlled semi-trailers,” Avery said.
“Controlled trials have been run where a Schmitz Cargobull reefer was compared with a rival,” he said. “The other trailer boasted radiused capping — caps that cover the corner sections where the trailer roof meets the bulkhead to round off the corner and improve air flow — side skirts and a rear roof scoop.
“The Schmitz trailer had side skirts, a tiny radius lip on the leading edge of the roof and small air deflector that sits on the rearmost edge of the trailer roof — where its purpose is to direct air coming off the roof into the low-pressure area immediately behind the trailer, thus cutting drag-inducing turbulence at the rear,” Avery said.
At first, there was virtually no difference in fuel economy when a tractor switched from one trailer to the other, he said. The individual add-on components then were removed one by one from the Schmitz trailer. Side-skirt removal caused fuel economy to deteriorate by 1.2%, and when the rear air-deflector device came off, it worsened by 0.78%.
The tiny radius on the leading edge of the roof turned out to be worth only 0.33%. So the total combined effect on fuel economy of all the aerodynamic features was a modest 2.3% improvement. This begs the question whether the up-front investment in aerodynamic add-ons is actually offering benefits of enough significance to warrant them, Avery said.
“The issues of aerodynamics and reducing the environmental impact of the haulage industry are here to stay and, essentially, it comes down to manufacturers being smarter in the design of trailers, which offer aerodynamic benefits from the outset,” Avery said. “This means identifying the areas of the trailer which influence air drag — namely the bulkhead, side surface, underside and rear — assessing the impact of weight and height on fuel consumption and developing products [that] address these issues directly.”
One trailer designer that does offer these benefits from the outset is the British firm Don-Bur Bodies & Trailers Ltd. Its Teardrop trailer design is licensed across Europe, South Africa, Canada and Australia.
“We launched the Teardrop trailer in 2007,” said marketing director Richard Owens. “Teardrop is based around an aerodynamic design that has a full-length curved roof, which mimics the perfect streamlined shape of a water droplet running down a sloped surface.
“The Teardrop is now very common in the U.K., but the original design is [almost a foot] higher than its flat roof counterpart [normally about 13.8 feet]. Whilst this did not present a problem for the U.K. road infrastructure, it certainly posed a challenge or two for the European market, which is restricted to a [13.1-foot] overall height limit.”
One of the key features of the Teardrop trailer is the low roof height at the rear. This measurement is key to the success of the design because it aids the reduction of the fuel-sapping partial vacuum created behind the trailer when moving at speed.
Because the height at the rear is dictated somewhat by the height of the overall roof curve, an about 13.1-foot height restriction normally would mean reducing a rear aperture to the point where it becomes operationally unworkable.
To overcome this challenge, Don-Bur had to re-engineer the chassis frame to a tapered design, which, in turn, lowered the rear floor height significantly. In addition, the top header on the rear-frame has been engineered to be as slim as possible. With this combination, the vehicle hunkers down to the ground, maintains a generous rear aperture height and keeps the roofline low.
Lowering floor height, however, poses a new set of challenges because dock heights generally are fairly standard at about 47.25 inches. A rear trailer floor height of about 34.4 inches creates a fairly large step that even the best dock levelers would struggle to reach. To compensate, Don-Bur introduced super-high lift suspension, which easily can raise the rear floor height back to about 47.25 inches when loading or unloading.
Not only do the height restrictions present issues to trailer builders in Europe, but truck manufacturers also have had to contend with the 13.1-foot issue. Euro VI, the European emissions standard that is the equivalent of the U.S. Environmental Protection Agency’s 2010 standard, is due to be implemented in January 2014, effectively merging both European and North American standards.
It has been neither cheap — one original equipment manufacturer said that the final cost of moving to Euro VI from Euro V will be in the region of 1 billion euros per manufacturer — nor simple. The key issue revolves around the extra cooling requirement that Euro VI demands and the packaging of that additional component into the existing 13.1-foot envelope.
“EGR for Euro VI causes a significant higher cooling capacity within the given vehicle packaging,” said Manfred Schuckert of Daimler Trucks, based in Stuttgart, Germany. “Normally, radiator sizes and fan sizes need to be increased, as well as the air flow through engine compartment has to be optimized. This may also lead to higher component temperatures within engine compartment with insulation consequences to the cab floor.
“Of course, to integrate this cooling capacity into existing vehicles is a real challenge. Almost everything changes under the cab and also, the cab itself or the setup height of the cab has to be optimized.
“When you are designing a new vehicle generation — as we did — it may be easier to find an optimized design,” he said.
Schuckert added that the already existing and soon-to-be-coming Euro VI vehicles show that, within the current dimensions, which are about 8.3 feet wide, 8.2 feet of maximal cab length and 13 feet high, “You can find a reasonable packaging design.”
European legislation will continue to dictate the design of European trucks, and changes to existing legislation that would favor the trucking industry are unlikely. The European rail lobby is a very powerful beast, but perhaps more damaging is the public image of the road transport industry. There is no real equivalent of the “Good Stuff, Trucks Bring It” campaign in Europe, and so the industry remains very firmly on the back foot.
Europe will adopt greenhouse-gas legislation similar to the standards that take effect in North America in 2014. This legislation may provide an opportunity for a fundamental review of a legal framework that many consider outdated and no longer fit for its purpose.