Finding ways to avoid tractor idling
May 1, 2006 12:00 PM
Like smoking in public places, truck idling has become socially unacceptable to the general public, Wendy Leavitt, director, editorial and marketing development for Fleet Owner, a sister publication of Refrigerated Transporter within Prism Business Media, said in opening a workshop session on the potential auxiliary power units offer in reducing total fleet fuel consumption. The session was held in conjunction with the Truckload Carriers Association annual convention in Kissimmee, Florida, March 12 to 15, 2006.
Not only have carriers become increasingly concerned about the cost of idling, the public has other objections as well. Noise from truckstops often tops the list of public concern as a reason for opposing the construction of a new facility, Leavitt said.
More than 30 states have anti-idling laws on their books now. Contrary to previous practice, some of those states such as California, Connecticut, and New Jersey have begun actively enforcing those laws, Leavitt said.
Sleepers idle most
Within the last several months, the American Transportation Research Institute, part of the American Trucking Associations, published a report based on a survey from a group of fleets operating more than 55,000 trucks. If the fleets operated daycabs, the report showed those trucks to idle about six hours per week. For fleets with sleeper tractors, idle time exploded to more than 28 hours per week, Leavitt said. Some fleets that spend a lot of time waiting to load or unload at distribution center docks have reported idle time as high as 14 hours a day.
Some fleet managers tend to think that idling is mostly a function of overnight parking, but a great deal of idling takes place during the workday as well, Leavitt said. Information from the Argonne National Lab suggests that the transportation industry in the US idles its vehicles an average of 1,890 hours per year at a cost of more than $4,500 per truck per year. Some shippers and receivers are taking steps to reduce idling at their facilities. For instance, Wal-Mart has banned truck idling at all its facilities, more than 1,400.
Truck equipment vendors have noticed the desire to limit engine idle time. As recently as 2000 and 2001, only nine or 10 systems were available to take the place of idling truck engines. Currently, industry offers about 40 different solutions to the idling problem, Leavitt said.
Cutting total fuel costs
Schneider National uses about 250 million gallons of diesel per year, Steve Graham, vice-president — purchasing, said. Increasing fuel economy by only 0.1 mile per gallon represents a saving of $6 million to $8 million, depending on variations in fuel prices, he said.
Changing engine technology is having a negative impact on fuel economy, Graham said. As the Schneider fleet fills with more and more engines using exhaust gas recirculation for emission control, fuel economy drops by about 5%. When ultra low sulfur diesel becomes the standard national fuel, economy will drop by another 2%. The last step along that path will be introduction of the new engines to meet the 2007 EPA rules that will reduce fuel economy by another 3%. “For years, the industry has worked with engines, drivetrains, and tires to find that much increased fuel economy, and in the space of just five years, the result of all that work will be taken away,” he said.
Fleets have several ways to make up for lost economy. At Schneider, the most important is reduction of out-of-route mileage. “For us, out-of-route miles are just pure waste; so, getting rid of those excess miles has a big payback,” Graham said.
Drivers insist on speed
Speed control is another factor that can improve fuel economy. For years, Schneider National ran slowly, but that policy began to impact driver retention. “Quite frankly, we were in the way of the average motorist, so we increased truck speed,” Graham said. “We have an internal debate about slowing the fleet back down, but the reality is that truck speed will probably stay the same.”
After excess mileage and higher speed, idling is the third big fuel economy factor that fleets can control. For years, Schneider National has idled engines less than a lot of other fleets, because drivers get incentive pay to shut the truck down at stops, Graham said. As a result, the payback at Schneider National from cutting idle time could be a little less than for many fleets. Fuel consumption at idle varies depending on the reason the engine is running. Data at Schneider National shows that trucks use between 0.7 and 0.8 gallon per hour if the engine is idled to keep the cab and driver warm. In a hot environment, turning on the air-conditioner requires more power from the engine, and fuel consumption rises to 0.9 to 1.1 gallons per hour, he said.
Excess idle time does more than consume fuel. Schneider National has data to show that running an engine at idle reduces the interval between oil changes. Idle time also has an impact on engine life. “We can't pinpoint the amount of increased cylinder liner wear, but we are positive that it happens,” Graham said.
Some analysts suggest that trucks spend 38% of the time at idle. For individual fleets, that figure can be as high as 50% idle time, Graham said. The target for idle time at Schneider is 5%. For most fleets at average road speed, a tractor runs about 2,300 productive hours per year. Cutting idle time from 33% to 5% would save a fleet more than 1,100 engine hours per year.
Changing driver habits
The drawback to any idle control process is that drivers find it extremely convenient to let the engine idle, Graham said. It takes a lot of training and other efforts to change driver habits to get them to limit idling unless fleet management is willing to use electronic monitoring and control. Automatic shutdown systems offer one solution.
Graham said that Schneider National's location in Green Bay, Wisconsin, has caused the company to look at cab heating first in its attempts to limit idling. The company uses heaters from Webasto. “While effective, heaters will not solve the idle problem if the outside temperature is -10° F,” he said.
Driver incentive programs can be problematic. “Some drivers develop conflicts with their fleet managers if they do not receive all the bonuses available,” Graham said. “We've seen instances where it looked as though the driver was idling the truck just to spite the fleet manager because of missed bonuses.”
If the need to conserve fuel is not a strong enough reason to limit idling, government and customers both are beginning to mandate it, Graham said. States are cracking down on idling trucks. “Our experience shows that law enforcement is fairly understanding as long as the driver is with the truck, but if the driver walks away from an idling tractor, they write a ticket,” he said. “A bigger issue is customer pressure. Like a lot of other carriers, Wal-Mart is our largest customer. They are pushing their idling ban much harder than state and local governments.”
Many products tested
Schneider National has tried a whole range of anti-idling solutions. One, automatic start-stop, did not work well at all, Graham said. “That is a system that starts the truck engine in response to a thermostat,” he said. “In extremely hot or cold conditions, the truck engine is starting and stopping constantly, so the driver can't get any sleep.”
Auxiliary generator sets may prove to be the best solution, because they heat and cool as well as keeping the truck batteries charged and the coolant warm for easy starting, Graham said. However, auxiliary power units also carry a high purchase price, he said. Another solution is external 110 VAC power, which is great if the truck parks at a truckstop every night. “More than 60% of the time, our trucks do not park in truckstops, so shore power doesn't do us any good,” he said.
Diesel-fired cab heaters do work. They are the solution that has worked best at Schneider National so far, Graham said.
Webasto Product North America produces fuel-fired heaters and bunk cooling systems, Reid Landis, marketing specialist for Webasto, said. In some areas of the country, as much as 52% of particulate matter put into the atmosphere comes from idling highway tractors, he said.
As a public policy matter, at least 22 states have laws against truck idling. In many cases, no idling laws are strictly enforced along Interstate highways and in rest stops. These no-idling zones are found throughout the country along the corridors crossed by Interstate Highways 5, 10, 40, 70, 75, and 95, Landis said. In some places no idling is enforced as much for noise reduction as for exhaust emission control.
Fuel-fired heaters such those made by Webasto blow warm air into the truck cab and sleeper. They also can be used to heat engine coolant. The fuel savings available from such heaters is significant in that one can operate for up to 20 hours on a single gallon of diesel, enough time to heat a truck for three nights, Landis said. In addition to fuel saving and low amperage requirements, fuel-fired heaters are quiet, he said.
Systems that once were known as generator sets have become much more than simple generators; they are now integrated auxiliary power units with the capability of supplying heating, cooling, and electrical power to run appliances in the truck and sleeper berth, Martin Duffy, vice-president of engineering for Thermo King Corporation, said. As more of these anti-idling devices come onto the market, the quality of comfort a fleet can provide for its drivers will become an attraction in recruiting and a factor in worker retention, he said.
Replace main engine power
An integrated auxiliary power unit should provide all the power that a driver can get from idling the truck engine, Duffy said. Typically, these systems include an engine and compressor mounted in a housing along one of the tractor frame rails. For air-conditioning, an evaporator mounts under the sleeper bunk, and the condenser unit attaches to the back of the cab. In addition to cab and sleeper comfort control, auxiliary power systems provide main engine block heating. This can be done by circulating tractor coolant through the auxiliary engine or with electric coolant heaters. The system is controlled from inside the truck cab, and usually can be programmed to start when the main truck engine shuts down.
Most auxiliary systems use a small, two-cylinder diesel engine. An alternator provides power for fans and for charging the truck batteries. Thermo King uses a belt-driven air-conditioning compressor; some other systems utilize an electric compressor. Some systems allow fleet managers to program operating instructions that the driver cannot change into the APU, Duffy said. However, they require very little attention from the driver, activating when the main engine is started at the beginning of a trip.
Integrated APUs require fairly complex installations and need a clear space along one of the frame rails. For instance, the Thermo King TriPac system needs 24 inches of frame space, Duffy said.
How quickly an auxiliary power unit will pay for itself depends on fleet utilization and average idling time. With TriPac, a fleet that idles more than 35% of total engine operating hours can expect a payback within 12 to 18 months, Duffy said. If the systems are properly financed, they will be cash flow positive from the first month of operation, he said. Based on an assumption of diesel fuel cost at $2.50 per gallon and idling the truck 10 hours a day, Thermo King says that fleets spend $6,500 per truck per year for engine idle time. In contrast, it would cost $936 to operate an auxiliary unit for a year.
Using an anti-idling system requires a culture change within the fleet that adopts it, Duffy said. The system must be automatic. If it is not automatic, drivers will not utilize it properly. In addition, the systems should have maintenance intervals that match normal tractor maintenance. It makes no sense to pull a tractor off the road just for APU maintenance, he said.
Design life of these products is about 10 years, Duffy said. This allows fleets to remove the unit prior to tractor trade-in and install it on a second tractor.
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