Idle time has more effect on litres per hour of fuel used than any other operation for mobile plant machines.
On IPWEA’s Ask Your Mates forum, Ballina Shire Council Fleet and Supply Coordinator Neil Smith wrote that it was difficult to find information on acceptable levels of idle time, and queried whether there was a benchmark idle time for excavators and loaders.
He explained one of the council’s 20T excavators is averaging 20%, which has reduced down from 41% since they started monitoring idle time data.
Recognising that benchmarking idle time can be something of a dark art, IPWEA Executive Officer Ross Moody says IPWEA is investigating developing a Practice Note on idle time, to be released in time for the November series of fleet workshops.
What is idle time, and how is it recorded?
Bundaberg City Council Manager Fleet Services and IPWEA Fleet Panelist Andrew Railz defines idle time as the period of time that a fleet assets engine is running, but the asset is not moving and/or working.
Railz says it is important to consider the different tasks the machinery will be engaged in when monitoring idle time.
“Fleet assets such as excavators and backhoes can remain stationary while still working, such as when digging a trench,” he says.
“Fleet assets that rely on the truck power take-off to drive work tools will also remain stationary while still working. Factors such as this must be considered when reporting on idle time and preparing policy documents.”
“There will always be periods of acceptable idle time, such as stopped at traffic lights and waiting while a truck is reversed into position for loading.”
The most common method of recording idle time is through the use of a GPS or telematics system. Other electronic devices such as data loggers will also record idle time.
However, Railz says caution must be taken when fitting GPS and telematics.
“GPS and telematics systems that are wired through the ignition only can give a false report of idle time,” he says.
“For example, if the ignition is on, the engine is off, and operator is listening to the radio, a false report of idle time can be given. Many GPS and telematics systems utilise an input from the engine to differentiate between ignition on, engine running, and ignition on, engine stopped.”
Because GPS/ telematics systems produce an enormous amount of data, Railz recommends using exception reporting when analysing the data, which identifies data that are outside the scope of what is considered a normal range.
Why is it important to reduce idle time?
Railz says the benefits of reducing idle time include decreased engine maintenance costs, longer engine life, reduced emissions, reduced noise levels, and fuel cost savings.
“The main focus for Bundaberg City Council, besides effective utilisation of the councils fleet assets, is the ongoing fuel savings from an anti-idling policy,” he says.
“In a recent example of a wheel loader, the amount of idle time for one year equated to approximately $12,000 in fuel for idle time alone. Obviously a certain percentage of that idle time is justified; however, there are still enormous savings available to us by monitoring engine idle time.”
City of Tea Tree Gully Technical Officer Plant and Equipment Maurice O’Connor weighed into the conversation on Ask You Mates, pointing out that unnecessary idle time is a “worse case scenario” for diesel engines.
“The result of letting a diesel engine idle for long periods of time is glazing of the bores,” he says.
“This results in oil usage and eventually requires a total engine rebuild, which as you all might know is very expensive. When this occurs there is the component of down time which is very expensive, remembering there may be the need to hire plant while the engine is being rebuilt. Adding up all the costs, letting diesel engines idle is unjustified.”
What do manufacturers say about idle time?
Komatsu National Operator Trainer, Supervisor Construction Aaron Marsh says he sets the benchmark across all machines at 20% idle time, based on data from the KOMTRAX satellite monitoring system installed in all new Komatsu machines.
“Obviously the higher the utilisation the higher the fuel burn, so what is important here is that the utilisation is effective,” Marsh says.
“This is why I always use the benchmark of 80% utilisation, 20% idle for everything, unless the application dictates higher idle time, such as trenching laying pipes.
From KOMTRAX data, Marsh found the following :
- Idle time on maintenance graders: very high, something like 35-40% idle, which could be due to operators leaving the machines on during smoko or lunch, or while doing other site related tasks;
- Loaders: same as above; and
- Construction machines: 20-30% idle time.
“Very few machines are operating above 90% utilisation across all variants of machines and applications,” Marsh says.
Marsh recommends considering the following when benchmarking, although he stresses it is not an exhaustive list.
- Average operation per day, per month, and annual hours
- Average start-up and shutdown times, and how many times that machine shuts down per day.
- What type of machines they are. In Komatsu machines, idle is counted on a wheeled machine when the RPM is under 1000. On a tracked machine, the idle is counted when the machine is stationary and known function of travel or levers are in operation.
- What type of working the machines are doing. Higher idle times are to be expected in a trenching application where the excavator is dropping in shoring boxes or lowering in suspend loads, and there are personnel in the trench.
How can you implement an anti-idling policy in your workshop?
If your workshop does not currently have a policy limiting the amount of idling, instigating one can be challenging. In the initial stages, Railz recommends opening lines of communication with managers, supervisors and operators.
“Chances are they have not considered idle time cost,” he says.
Then, determine how the organisation will track idle time.
“If using GPS or telematics devices, privacy will need to be considered as part of any policy,” Railz cautions.
To create a fair and reasonable policy, Railz recommends the following:
- Any engine that is expected to idle for longer than five minutes is to be shut down.
- Communicate with all stakeholders why the system is being implemented and how it will work.
- Start by monitoring idle time on a monthly basis – identify areas that have large amounts of idle time.
- Understand how fleet assets are being utilised – do operators require training or a change in work practices?
- Meet with supervisors and outline areas of concern.
- Provide idle reports to all staff and give opportunities to provide feedback.