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Idle Reduction

commuteres idling in a traffic jam Idle reduction is an effective method of reducing harmful pollutants and has added benefits of lowering fuel consumption, saving money, curbing maintenance costs, and prolonging engine life. The United States (US) Department of Energy’s National Idling Reduction Network News offers information and highlights about projects around the country, and the Alternative Fuels and Advanced Vehicles Data Center (AFDC) provides extensive information on technologies, regulations, and other topics.

Although many people associate unnecessary idling with heavy-duty vehicles, idling occurs in every sector of transportation, from freight trucks to passenger cars. In many cases, a wide variety of technological solutions is available to further reduce or eliminate unnecessary idling in several sectors.

Many states and localities, including several in North Texas, are enacting laws that prohibit unnecessary idling. An updated inventory of these rules is available from the American Transportation Research Institute.  In North Texas, idle reduction has become a part of many different Regional Transportation Council programs.  The North Central Texas Council of Governments (NCTCOG) administers the following initiatives devoted to reducing unnecessary idling:

To learn more, click on the various vehicle types below.

Construction Equipment

  • Construction equipment is estimated to be at idle for approximately 15 percent of all operating time, according to EPA non-road testing procedures.  Some of this idle time may be eliminated through more stringent idling policies that simply modify behavior. To date, idle reduction measures have been incorporated into construction contracts for various projects in the states of Connecticut, Illinois, Massachusetts, New York, and Oregon.  Such measures will likely become more common in the future.

  • Although few aftermarket technologies are currently available for construction applications, auxiliary power units (APUs) are suitable for some equipment applications.  For certain construction activities, electrified equipment may be a good option to replace traditional diesel equipment and would eliminate idling altogether.  External power needs, which are often supplied by a diesel generator, may be fulfilled by using a stationary fuel cell instead, which virtually eliminates emissions and drastically reduces fuel use. 


Heavy-Duty Trucks

  • EPA estimates that one heavy-duty truck could save as much as 1,900 gallons of fuel each year simply by eliminating unnecessary idling.  Fortunately, this sector benefits from a wide variety of technological solutions for excessive idling, including both on-board and on-site products.  On-board products such as evaporative coolers or bunk heaters offer climate control to ensure driver comfort overnight or while stopped for extended periods of time.  Auxiliary power units (APUs) provide a power supply for a wide range of driver needs, including climate control as well as electrical power for computers or other appliances, while allowing the main engine to be turned off.  Some engine manufacturers also provide idle management systems that program the engine to turn on and off automatically.   

  • US EPA maintains a list of verified idle reduction technology categories and manufacturers through the National Clean Diesel Campaign


Light-Duty Commerical Vehicles

  • In April 2007, Clean Cities published an article estimating that commercial light-duty vehicles in America could be burning over 600 million gallons of fuel each year due to idling alone.  Although technological options for light duty vehicles are not as varied as those for heavy-duty vehicles, available products include coolant heaters, air heaters, and energy recovery systems.  Coolant heaters are available for both gasoline and diesel light duty vehicles and use a small volume of fuel to heat coolant and circulate the fluids after the engine has been turned off.  Air heaters, which are self-contained heater units, keep passenger compartments warm by providing hot air into the vehicle cab.  Energy recovery systems utilize an electric pump to keep the vehicle’s heater running after the engine is turned off. 

  • Additional information on all these products, including manufacturers, is available through the AFDC.  Some cooling systems may also be suited to light duty applications.



  • Locomotives have unique needs due to the particular operating characteristics of large locomotive engines.  Both mobile and stationary idle-reduction products are currently available to address idle-reduction in this sector.  Automatic shut-down/start-up systems (start/stop), auxiliary power units (APUs), and diesel driven heating systems are all technologies that may be installed on the locomotive itself.  Electric driven heating systems also offer remote power but require certain on-board components to be present.  More details, including specific product and manufacturer information, are available through the EPA’s SmartWay Transport Partnership. 

  • EPA also maintains a list of verified idle-reduction devices, including some for locomotives, through the National Clean Diesel Campaign.

  • In addition,  some manufacturers are producing locomotives that come pre-equipped with start/stop technologies, while others are incorporating hybrid technology.  RailPower Technologies Corporation manufactures hybrid locomotives which are used in switchyard applications.  Switcher locomotives operate in start-stop patterns continuously, and the hybrid equipment uses up to 60 percent less fuel than traditional diesel locomotives and reduce idle time significantly.  In line-haul applications, hybrids can result in a 10 percent increase in fuel efficiency.  General Electric unveiled their hybrid line-haul locomotive in May 2007, which is the first such hybrid locomotive in the industry. 

  • Finally, research and development is ongoing for fuel-cell locomotives, which would eliminate idling emissions completely.  Companies looking to invest in new equipment should seriously consider these options when making purchasing decisions. 


Passenger Vehicles

  • Citizens also contribute to the problem of unnecessary idling in their daily activities, such as warming the car in the morning, waiting in the drive-through at lunch, or running the engine in the parking lot for a few extra minutes when arriving at a destination.  Often, drivers don’t realize that these activities result in unnecessary air pollution.  Idle reduction in this case is best impacted by behavioral changes, and involves only an increased level of awareness and personal commitment to turn off the car engine as soon as possible.  When drive-through lanes are long, park and walk inside rather than idle in a slow line.  Once a car is parked, exit the vehicle quickly to avoid the temptation of running the engine to keep the air conditioning or heat on. 

  • The AFDC provides tips on how every driver can reduce unnecessary idling.  Technological solutions for passenger vehicle idling are limited.  However, advanced technology vehicles such as hybrid-electric cars have the capability to shut off the gasoline engine while idling for several minutes.


School Buses

  • School bus idle reduction is an especially important initiative because of the susceptibility of school aged children to adverse health impacts resulting from prolonged exposure to harmful emissions from high-emitting diesel school buses.  School buses traditionally queue in a long line while waiting for students after school or at special events, often with the engine continuously running.  This results in extremely concentrated areas of diesel exhaust pollution, which has been documented to cause various health problems. 

  • One of the most effective tools for reducing idling for school bus is the enactment of anti-idling ordinances or policies by cities, schools, and school districts in combination with driver education.  EPA maintains a website devoted to school bus idle reduction under the Clean School Bus USA Program.

  • Hybrid electric school buses are currently under development and may provide another technological option by allowing the on-board heating and cooling elements to be powered by batteries, as opposed to the internal combustion engine, while the bus is stationary.  Demonstration projects are underway in several states.

For more information on school buses, visit the North Central Texas Clean School Bus Program.


For additional information on idle reduction, visit the links below:

Note: The inclusion of any technology vendor does not indicate an endorsement of the product, nor a certification or verification of the technology. The North Central Texas Council of Governments intends for this to be utilized for informational purposes only.

4/27/2018 SP//CH %Arc

 North Central Texas Council of Governments | 616 Six Flags Drive P.O. Box 5888 Arlington, TX 76005-5888
 Main Operator: (817) 640-3300 | Fax: (817) 640-7806