Putting the Brakes on Idling Vehicles

By Riley Hutchings and Kim Tyrrell | Vol . 26, No. 34 / September 2018

LegisBrief logoDid You Know?

  • According to the U.S. Department of Energy, eliminating personal vehicle idling would be equivalent to taking 5 million vehicles off the road. 
  • Twenty-three states and Washington, D.C., limit idling by some or all vehicles.
  • Before a similar federal law went into effect in March 2018, all but five states had increased their truck weight limit by between 400 pounds and 550 pounds to account for on-board idle reduction technologies (IRTs).

Idling—running a vehicle’s engine while it is stationary—wastes an estimated 6 billion gallons of fuel into the air each year. Exhaust fumes from cars and other vehicles have been linked to asthma, cancer, cardiac disease and other serious health risks, particularly in vulnerable populations. According to recent studies by the World Bank and the Health Effects Institute, nearly three times as many people, roughly 100,000, die from air-pollution-related deaths compared with fatalities from car accidents.

Whether intentional or not, most people idle every day. Common examples include waiting in line at a drive-thru or to pick up a child at school, and getting stuck in a rush-hour traffic jam. Truck drivers frequently rely on idling to generate electricity to maintain cabin temperature while they sleep, though on-board idle reduction technologies (IRTs) are widely available. IRTs are energy sources that provide services like air conditioning or electricity, allowing truck drivers to shut down their main propulsion engines and reduce idling.

State Action

Over the past two decades, state legislatures have enacted various forms of legislation to minimize vehicle idling. Nine states—Colorado, Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New Jersey, Texas and Vermont—and Washington, D.C., limit idling to between three and five minutes for most vehicles. Another 14 states limit idling for certain vehicles, such as school buses, state-owned vehicles or vehicles over 10,001 pounds. 

Further, 18 states have grants, loans, tax credits or pilot programs to provide incentivizes for adopting idle reduction technologies. Those states are Alabama, Arizona, Arkansas, California, Colorado, Georgia, Illinois, Indiana, Maryland, Massachusetts, Minnesota, New York, North Carolina, Ohio, Oregon, Pennsylvania, Tennessee and Vermont. Colorado, Maryland, Massachusetts and Vermont are currently the only four states that both offer incentives for IRT adoption and limit idling for most vehicles. Colorado goes one step further with its idle reduction program—a collaboration between federal, state and local governments to improve air quality by minimizing idling.

In addition to their own strategies, states are also required to develop State Implementation Plans (SIPs) to meet Environmental Protection Agency (EPA) regulations known as the National Ambient Air Quality Standards (NAAQS). The standards limit six major air pollutants—carbon monoxide, lead, nitrogen dioxide, ozone, particle pollution and sulfur dioxide. Car engines emit carbon monoxide, nitrogen oxides, particle pollution and sulfur dioxide. At least 23 states refer to reducing engine idling as a strategy to improve air quality in their SIP proposals.

Many cities or counties within states have additional idling ordinances. Arizona law requires counties to adopt and enforce idling time limits. Indiana, Utah and Vermont require their boards of education to adopt idling policies for school bus drivers.

Tackling traffic congestion is another approach to reducing idling. At least 20 states use high occupancy vehicle (HOV) lanes to promote carpooling. Other techniques include ramp metering, variable speed limits, reversible lanes, use of shoulder lanes during peak periods, toll roads with automatic sensors, quick response to traffic incidents, and traffic communication via signs or phone applications.

Many states use idling awareness campaigns to educate the public on the effects of vehicle idling, especially near schools, while others subsidize bus- and truck-driver trainings on no-idling techniques.

Federal Action

Three current federal statutes related to reducing vehicle idling are:

  • 23 U.S.C.A. §127 (2018) increases the maximum weight limit for trucks by up to 550 pounds to account for idle reduction technologies.
  • 26 U.S.C.A. §4053 (2008) exempts any device that reduces idling from retail excise tax.
  • 42 U.S.C.A. §16104 (2005) allocates funds to the administrator of the EPA to facilitate research on the benefits of IRTs and to establish a program for IRT adoption through the SmartWay Partnership (discussed below).

In addition, the U.S. Department of Energy operates two programs to minimize idling, and the EPA has two initiatives to support IRT research and emissions reduction.   




U.S. Department of Energy

Clean Cities Coalition Network

A coalition of local businesses, state and local government agencies, and community organizations collaborate to reduce petroleum use in the transportation sector, which includes idle reduction measures.

U.S. Department of Energy

The National Idling Reduction Network

A coalition of businesses, government agencies, organizations and research centers work to identify effective solutions to idling.

U.S. Environmental Protection Agency

SmartWay Transport Partnership

This program to help the domestic freight industry operate efficiently, and includes monitoring and researching IRTs.

U.S. Environmental Protection Agency

Clean Diesel Program

This program supports projects that improve air quality by reducing harmful emissions.