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Prime Mover Magazine


Scania Fuel Duel

Scania Fuel Duel

What do you get when you run two identical Scania B-doubles down the Hume, one at 100km/h and one at 90km/h? A number of benefits that might just make a big difference to the bottom line!

It’s 6.30am on a Monday morning at the Scania dealership at Prestons in Sydney’s west when two B-doubles roll out the gate bound for the Hume and headed to Melbourne. Nothing really different here as trucks do that every day and night of the week, but in this instance the two combinations, while identical in specifications and weight, will travel the interstate route with one speed limited to 100km/h, while the other is restricted to a top speed of 90km/h in an exercise named the Fuel Duel.

The Fuel Duel was arranged by Scania to explore the benefits of running one vehicle slower, examining fuel consumption gains, environmental pluses, safety attributes and, importantly, the difference in trip times.

Now there are many transport companies that have limited trucks to slower than the legal 100km/h to concentrate on saving precious diesel and to increase safety. The track record established by these operations has seen huge reductions in fuel usage and very tangible safety gains, but there could be a long list of other benefits available simply by backing-off the throttle.

Scania decided to put this to a practical test and two R560 prime movers coupled to B-doubles, each unit grossing 58.7 tonnes, made their way to Melbourne to see what difference there was between the trucks for the journey.

The Scania 16-litre V8 engine produces 560hp (412kW) of power at 1800rpm with maximum torque of 2700Nm between 1000 and 1400rpm, driving through the Opticruise overdrive transmission to rear axles with a final drive ratio of 3.42:1.

As the trucks rumbled onto the M7 Motorway to join a reasonably heavy traffic flow there was very little between them in the performance stakes, each keeping pace with other vehicles on the road. Traffic was constant until well out of Sydney and the B-doubles were less than a kilometre apart due to congestion and motorists travelling at inconsistent speeds.

It was not until well past the Campbelltown exit that traffic did seem to reduce and both trucks were placed into cruise for the journey. The rules were simple: bring the tucks to top speed, lock in cruise control and simply sit back and enjoy the ride in the comfort surroundings letting Opticruise look after the gear changes, the retarder handle the downhill runs and concentrate on the road.

Scania organised this comparison not to promote its products but simply look at what can be achieved in fuel savings and illustrate benefits to the environment. The trucks were sourced from the Scania rental fleet with one having travelled almost 70,000 kilometres while the other had near 90,000 on the odometer.

“This experiment is very important because it shows quite clearly the relationship between cruising speed and fuel consumption, and of course, carbon dioxide emissions,” said Roger McCarthy, Managing Director of Scania Australia.

“With the impending Carbon Tax, and greater environmental awareness, Scania feels the time is right to reignite the debate around the benefits of voluntarily reducing cruising speed limits.

“We also know that travelling at 90km/h offers drivers additional time to help them avoid an accident, plus reduce braking distances as well as reduce fatigue.”

This was the second run along the Hume for the trucks as they travelled from Melbourne to Sydney with driver trainers Alan McDonald and Peter Huddle seeking to gain the best from the trucks in both directions, while the return leg was to see Australian Trucking Association CEO Stuart St Clair as passenger in one and Prime Mover editor Peter Armstrong in the other.

Just to keep all things fair and equal the speed limiters were reversed in Sydney for the return leg, not favouring either truck in the final results.

The northbound segment, covering a total distance of 767.3 kilometres, achieved some interesting results – noticeably fuel. The Scania running at 90km/h returned a figure of 1.708376007 km/L while the 100km/h truck came in at 1.554461863 km/L, a difference of 0.153914145. This figure may not sound much but it is substantial – almost 10 per cent.

What is interesting is the estimated CO2 produced along the way with the truck travelling at 90km/h putting out 1190.221kg while the other unit posted a figure of 1308.441kg, so the impact on the environment is lessened considerably at the lower speed.

The Scania Fleet Management System was used to monitor every aspect of the journeys, to ensure the vehicles stayed on the route, stayed on schedule as well as keeping a watchful eye on consumption and emissions.
As a result of the drive Scania was able to determine:

• Total journey distance: 768km each way, 1536km round trip
• From Melbourne to Sydney, the truck travelling at 100km/h used 45 litres more fuel than the truck travelling at 90km/h (494 vs. 449 litres)
• From Sydney to Melbourne, the truck travelling at 100km/h used 11 litres more fuel than the truck travelling at 90km/h (486 vs. 475 litres).
• From Melbourne to Sydney, the truck travelling at 100km/h emitted 118kg more carbon dioxide than the truck travelling at 90km/h (1308kg vs. 1190kg)
• From Sydney to Melbourne, the truck travelling at 100km/h emitted 30kg more carbon dioxide than the truck travelling at 90km/h (1290kg vs. 1260kg)
• From Melbourne to Sydney, the average speed across the entire journey was 85km/h for the truck limited to 100km/h and 77km/h for the truck limited to 90km/h.
• From Sydney to Melbourne, the average speed across the entire journey was 88km/h for the truck limited to 100km/h and 80km/h for the truck limited to 90km/h.
• From Melbourne to Sydney the differential in actual driving time amounted to 40 minutes.
• From Sydney to Melbourne the differential in actual driving time amounted to 53 minutes.

Overall, the time differential amounts to around four seconds per kilometre travelled.

While the fuel saving on the outward journey amounted to 10 per cent, the overall round trip saving was 6 per cent.

As a real world example, for a vehicle travelling the Hume five times each week (a distance of 768km per trip, 3840km in total) over the course of a year, an operator could save around $10,000 per vehicle (at a diesel price of $1.27c per litre – allowing for the diesel fuel tax credit) running at 90km/h instead of 100km/h.

“From an operator’s perspective the financial savings would add up to a substantial sum each year, per truck,” Roger said. “This goes straight to the bottom line.

“If you were to multiply that across a fleet you can quickly see the magnitude of the savings. Then if you take into account the CO2 savings as well as the potential for greater levels of road safety from drivers travelling slightly less fast being able to have better reaction time, you can see that it is a win-win-win situation.”

In December 2010, Scania conducted a similar run from Melbourne to Tarcutta, pulling single trailers.

“The results we obtained then were consistent with the results we have recorded with B-doubles, suggesting there are meaningful benefits to be obtained by a wide variety of operators,” Roger said.

“It will not only be line-haul fleets that can benefit from the lower speed, but any operator covering long-distances at constant cruising speeds,” he said.

Stuart St Clair, ATA Chief Executive said that travelling at 90km/h did not seem slow.

“The way the engine handled its torque was beautiful, I loved the smoothness of the gearchanges. There was less fatigue, and less distraction.

“The performance of the vehicle speed limited to 90km/h was good, especially coming off hills. It won’t run away, and the retardation process is superb. It will give a saving on brake linings as well as driver fatigue.

“On regional and rural roads I often drive slower. It’s more comfortable,” he said.

“This test reinforces the message that fuel savings are possible. Consumption savings and environmental benefits can be achieved,” he added. “We will be faced with a Carbon Tax whether we like it or not.

“There are still many people who run too fast. They don’t care about fuel. I don’t think the industry is serious yet (about fuel). Fuel is not expensive compared with Europe.

“If the industry is serious about saving fuel, this is one way. Another is driver training, and an auto gearbox. But lots of drivers still like to rev engines.

“I am not suggesting the ATA would support mandatory lower speed limits. I am not saying that at all. But if you want to be serious about saving money and saving fuel, this is a way to do it,” Stuart said.

The Fuel Duel proved beyond a shadow of a doubt running costs can be reduced, safety is improved, environmental gains are proven and fatigue is lessened – all through backing off the throttle.

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