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Reducing Vehicle Idling

What is Idling?

graphic of a hypothetical no-idling sign

When a vehicle's engine is on but the vehicle is not in motion, it is idling. Sitting at traffic lights, waiting in a running car to pick someone up, trucks idling while their drivers make deliveries or sleep during rest stops - these are all examples of idling.

Why Care About Idling?

Although many individual idling episodes are small, the cumulative impacts of idling are large! Consider that idling in the United States uses more than 6 billion gallons of fuel at a cost of more than $20 billion EACH year. Add to that the costs of maintenance related to the extra engine running time and the added emissions of particulates (PM10), nitrogen oxides (NOx), carbon monoxide (CO) and carbon dioxide (CO2) related to idling, and it becomes clear that the financial and societal costs of idling are too large to ignore. Other reasons to reduce idling include the fact that many states and municipalities are adopting stringent anti-idling laws and imposing large fines for those who violate the laws, and that the federal and many state governments offer tax incentives for those who adopt idling reduction measures.

How Can Idling Time be Reduced?

That depends on the type of vehicle and why it is idling. The good news is that reducing idling time need not compromise driver or passenger comfort.

For light-duty vehicles such as passenger cars, the answer is pretty simple; turn off the engine whenever running it is not truly necessary, such as while waiting to pick up childern after school, waiting at long freight train crossings, or waiting for someone at the grocery store. For light-duty vehicles that require more extensive heating and power support, retrofits such as air heaters and auxiliary power systems can fill the gap.

For medium- and heavy-duty vehicles such as tractor-trailer trucks and locomotives, the answer depends a little more on why the vehicle is idling. The table below shows typical idling scenarios for light-, medium-, and heavy-duty vehicles, and suggests ways idling could be reduced in each scenario.

Vehicle Type Reason(s) for Idling Typical Amounts of Time Involved Possible Alternatives
Passenger car or truck Driver comfort during standing; concerns about vehicle restarts in cold weather; need to power electronics 0-240 minutes Auxiliary power systems, air heaters, and coolant circulators
Light truck Driver comfort during standing; concerns about vehicle restarts in cold weather; need to power electronics 0-240 minutes Auxiliary power systems, air heaters, and coolant circulators
Passenger bus Driver and passenger comfort during standing; concerns about vehicle restarts in cold weather and to keep the engine warm/cool 0-120 minutes Heaters to enhance driver comfort and keep the engine warm
Heavy-duty truck, workday idling Driver comfort during standing time at delivery depots or intermodal facilities (workday truck idling) and to keep the engine warm 0-240 minutes or longer Heaters or coolant circulators to enhance driver comfort and keep the engine warm
Heavy-duty truck, overnight rest idling Driver comfort and electricity for appliances, lights, and electronics while parked for rest stops 0-48 hours Diesel-fired heaters, electrified parking spaces, thermal storage and battery-electric air conditioners, auxiliary power units
Medium- or heavy-duty truck Power take-off (PTO) 0-8 hours Hybridization to use supplemental battery, hydraulics, or engine that runs PTO equipment
Locomotive Keep engine warm and prevent toilet from freezing 0-18 hours Auxiliary power or plug-in systems

Which Alternatives to Idling Are Best?

Again, the answer depends on the type of vehicle and why it is idling; there is no one-size-fits-all solution to idling. With support from the U.S. Department of Energy, Argonne National Laboratory has pioneered research into the science and economics of reducing idling, resulting in several landmark studies and tools to help drivers and organizations determine the best and most cost-effective ways to reduce the time they idle their vehicles.

Funding

This work is supported by the U.S. Department of Energy Office of Vehicle Technologies.

More

Related Items

Argonne's Idle Reduction Research

Idle Reduction Tools and Outreach Materials

Argonne's Idling Publications

Savings Calculator for Heavy-Duty Vehicles
(Excel format)
(PDF format)

Savings Calculator for Light-Duty Vehicles
(Excel format)
(PDF format)

Contact
Linda Gaines
lgaines@anl.gov

Search for Publications about Idling

 


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