Idling Reduction:
Impacts

How much fuel is consumed by unnecessary truck and locomotive engine idling?

Combined, truck and locomotive idling consumes over 1 billion gallons of diesel fuel annually.  Long duration truck idling consumes approximately 960 million gallons of diesel fuel annually, and locomotive switcher idling consumes 60 million gallons of diesel fuel annually.

Based on comprehensive EPA testing of idling heavy-duty diesel trucks, the average truck consumes .80 gallons of fuel an hour.

• For fuel consumption and oxides of nitrogen emission information on idling trucks, view "Study of Exhaust Emissions from Idling Heavy-Duty Diesel Trucks and Commercially Available Idle-Reducing Devices"  (EPA 420-R-02-025, October 2002)  1.2M PDF

EPA's test program took into account wide ranges of idling behavior to better represent actual idling.  For example, trucks were tested from low to high engine speeds (600-1200 rpm), with air conditioning or heat operating or no accessory load, in a controlled environmental chamber heated and cooled, and with different engine models and manufacture dates.

Based on industry publications, locomotive switcher idling consumes 3-4 gallons of fuel per hour.  In extremely cold weather (below 15^o F), many railroad companies implement a winter policy of idling at notch setting 3, thereby consuming 8-11 gallons per hour at idle.

What are the emissions at idle?

Annually, truck long duration idling emits 11 million tons of carbon dioxide, 180,000 tons of nitrogen oxides annually and 5,000 tons of particulate matter.  For detailed information about idling nitrogen oxide emissions view EPA's Study on Long Duration Truck Idling (above).

• For detailed information about idling particulate matter emissions view the study "Particulate Matter and Aldehyde Emissions From Idling Heavy-Duty Diesel Trucks"  683K PDF

Annually, locomotive switcher long duration idling emits 12,000 tons of nitrogen oxides and 500 tons of particulate matter.

• For detailed information about the nitrogen oxide and particulate matter emission factors for locomotive engines view the "Guidance for Quantifying and Using Long Duration Switch Yard Locomotive Idling Emission Reductions in State Implementation Plans" (EPA420-B-04-002, January 2004)  343K PDF

What are the truck maintenance and engine wear costs at idle?

The trucking industry has analyzed the impact of idling on the engine, both in terms of maintenance and engine wear costs.  Long duration idling creates more oil and oil filter deterioration.  While the engine manufacturer factors in normal idling times as part of the maintenance, excessive idling will create the need for more oil and filter changes. Similarly, the longer the idling time, the sooner the engine will need to be rebuilt.  Engine wear is a function of fuel consumed, and long duration idling consumes much fuel.  The trucking industry estimates that long duration idling costs the truck owner $1.13 per day. This is based on the need for more oil changes and sooner overhaul costs.