Idling 101

What Is Idling?

Idling occurs when a vehicle’s main engine is running but the vehicle is not moving.

Why Does Idling Occur?

Idling occurs for a variety of reasons…

  • Safety
  • Comfort/Convenience
  • Periods when a vehicle is waiting to move forward
  • Operation of hydraulics or other onboard equipment powered by the main engine
  • Vehicle care and maintenance, repair, and inspection

Examples of idling activities include…

  • Powering HVAC and onboard accessories during mandatory rest periods for truck drivers
  • Warming up a vehicle
  • Stopped in traffic or at a signal
  • Waiting
  • Operating medical and other equipment in emergency situations
  • Loading and unloading passengers
  • Operating equipment necessary for a job

Depending on the situation, idling may be…

  • Necessary – Activities for which there is currently no alternative to idling. For example, in some cases repair of a vehicle requires the engine to idle.
  • Avoidable – Activities for which there are alternatives to idling. For example, auxiliary power units (APUs) can power heat/air and other accessories during mandatory rest periods for truck drivers instead of the main engine.
  • Unnecessary – Operator behaviors that should not require the engine to idle. For example, in some cases waiting in a vehicle with the engine running is not necessary.

Why Reduce Idling?

It all adds up to cleaner air!  Reducing idling can improve quality of life in Louisville by improving overall air quality.  Idling emissions affect the environment, public health and the economy of communities around the country.

• Environmental and Health Impacts

Reduce idling, reduce pollution. Vehicles emit a variety of air pollutants including fine particles, volatile organic compounds, toxic chemicals and greenhouse gases, among others. These pollutants can contribute to increased rates of cancer, asthma and other respiratory illnesses.

To protect public health, the Environmental Protection Agency (EPA) establishes air quality standards to insure the air we breathe is safe. Louisville’s air quality has straddled a fine line of attainment with the standards for fine particles and ozone. In a valley with unpredictable weather patterns, an unexpected heat wave, drought or air stagnation can make the difference between attainment and nonattainment in the future. Decreased idling activity can further reduce concentrations of fine particles and ozone in the air and help widen this attainment margin.

See EPA’s Guide to Air Quality and Your Health for more information on health effects.

• Economic Impacts

Reduce idling, save money. Over time, the costs of wasted fuel and increased maintenance from idling can affect the bottom line of businesses and households alike. Reducing idling activity can significantly decrease these costs for all vehicle owners and operators.

On a larger scale, a comprehensive air pollution reduction plan that includes idling reduction will lead to improved air quality, which can increase economic productivity by attracting more business and industry, reducing absences from work and school, and reducing health care costs.

How to Reduce Idling?

There are a variety of ways to reduce idling…

  • Regulation – Communities around the United States have enacted idling restrictions. The map of idling restrictions shows state and local restrictions on the books and those currently being developed as of April 2008. The scope, exemptions and enforcement of these restrictions vary widely. See the Comprehensive Idling Restriction Review for a complete list of idling regulations. See Idling Reduction Working Group for more on Louisville’s efforts to reduce idling.
  • Use of Technology – Development of idling reduction technology, or “engine-off” technology, for commercial vehicles and equipment is on the rise. Technologies such as auxiliary power units (APUs), auxiliary heaters and shore electrification are already available in many markets. See EPA’s Idle Reduction Technologies for more information on alternatives to idling.
  • Improved Planning – Many steps can be taken throughout the community to reduce or eliminate situations in which idling occurs. Communities can improve traffic flow and reduce dependence on single occupancy vehicles through integrated land use and transportation planning. Business and industry can also help reduce idling activity through improved logistics planning at distribution centers, warehouses, retail stores and many other sites where vehicles commonly idle.
  • Education and Outreach – Driver awareness of the costs associated with idling activities is relatively low. Education and outreach efforts to dispel common misconceptions about idling can change driver behavior and lead to idling reductions. See the following links for more about idling misconceptions: