Tag Archive for idling

Truck Idling versus Fuel Economy: Every Minute Counts

–By Chuck Lane, Solution Engineer, Webtech Wireless
Idling for longer periods of time—whether at a job site, railroad crossing, or pulled off to the side of the road to make a cell phone call—consumes gasoline that could be saved by simply turning off the engine.


Idling truck Eliminating an hour of idling per day produces significant cost savings and emissions reductions over the course of a year. For fleets operating Class 3 and larger trucks, the savings are even more significant. For example, a typical truck burns a half-gallon of Diesel fuel for every hour it idles and, in the process, adds the equivalent of 40 miles of wear-and-tear to the engine. If you want to green your fleet by reducing emissions, you need to decrease fuel consumption, and the easiest way to do so is to decrease unnecessary idling.

For example, every gallon of gasoline burned idling creates 19.5 lbs. of CO2. Similarly, every gallon of Diesel burned idling creates 22.4 lbs. of CO2

The key is to be able to measure idling accurately. There are idling reports (using non BUS connectors) that simply calculate the time between ignition on and ignition off, and then subtract the time while moving to equal the actual idling time. This type of idle reporting, however, proves to be inaccurate for drivers that use the ignition to access the vehicle for things like radio and air conditioning, while leaving the engine off (Key On, Engine Off).

This type of scenario can be mitigated. If we install the Webtech Wireless Locator (GPS Unit) ignition wire to ignition on—avoiding accessory key position—the driver can then go to accessory position without affecting the Locator operation.  This is true for most light-duty vehicles. Most heavy-duty trucks/tractors have a key on and engine off alarm, so drivers don’t spend a lot of time in the key on, engine off scenario (the alarm is a soul piercing, shrieking high-pitch buzzer).

Webtech Wireless conducted a study with a major customer where we compared ignition on/off durations, to engine on durations.  The plan was to target this key on, engine off scenario.  We found a 2.7 percent deviation between ignition cycles and engine cycles. So for 100 minutes of key on, 97 minutes were engine on.  As this was so low, the customer accepted the Webtech Wireless Idle report using ignition cycles and not engine cycles.

Of course, the Non-Bus Idle report is completely different from the BUS-related (such as JBUS, CanBus, or OBDII) reports that actually report engine hours to be used in idle calculations. Webtech Wireless conducted the above study with the assumption that future non DLOGS (Driver Logs)/ HOS (Hours of Service) installations would avoid the BUS entirely.  We really have no control over the BUS and the failed elements that sometimes occur with customer vehicles.  We’ve already enabled odometer GPS to eliminate the BUS impact on the Locator odometer.  We found that over 2,500 tractors measured during fuel tax testing, had more errors with BUS than with non-BUS GPS (see Why Increased Accuracy Matters).

While it’s possible to gather idling information from both GPS and BUS related statistics, any vehicle that has a DLOGS/HOS system must be intrinsically synchronized with the vehicle BUS connection. In laymen’s terms, DOT (Department of Transportation) compliance requires a BUS connection.  We can’t avoid BUS anymore, if the solution is supporting DOT.  Fuel tax compliancy does not require BUS connectivity.  IFTA (International Fuel Tax Agreement) regulations state ‘use an odometer’, and don’t require that the vehicle BUS odometer be the only one used.

In conclusion, non DOT system installations can use ignition and GPS data to measure vehicle idling accurately. Reducing unnecessary idling is the simplest way for a fleet to reduce fuel costs and unnecessary emissions. In addition, excess idling causes needless engine wear-and-tear and unnecessary noise pollution. A typical goal for many fleets is to reduce engine idling time to less than 5%, a goal that motivates many fleets to implement anti-idling initiatives.

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