The Technologies & Benefits to Improving Haul Road Condition & Payload Distribution

Posted by on Mar 23, 2012 in Equipment, Technology | 23 comments

The Technologies & Benefits to Improving Haul Road Condition & Payload Distribution

The production and cost benefits associated with having a correct load balance on a haul truck and improving haul road conditions are difficult to quantify on paper and therefore a lot of mines do not make it a part of their standard operating procedure/best practice. But it is a relatively easy change to make to yield lower cycle time, higher production and lower costs. The premise is to create an environment where the truck is operating as close to design parameters as possible; in this blog entry, we will only focus on the design parameters of road conditions and load balance and how to utilize technology to monitor, analyze & improve these parameters.

My experience with open pit haulage has been with Caterpillar mechanical 240ton trucks (793x) so this article will use the Caterpillar line of products in the examples of technology[i]. The same best practice strategies should apply to other OEM haul trucks and if your truck isn’t currently equipped with the technologies described from hereon, there are 3rd party technologies you can look into if. Contact me if you need some direction.

First, let’s look at the “perfect” environment for haul truck (the environment which spec sheets are based on, for the most part):

1. Truck weight when loaded should be distributed as:

  • •1/3 of weight to front axle
  • •2/3 of weight to rear axle
  • •1/2 of weight to the right side
  • •1/2 of weight to the left side

2. Truck is traveling at 0% rolling resistance. The smoother the road is, the lower the rolling resistance %. 0% is “impossible” in reality; in general, 1% is great, 2% is average. A high rolling resistance causes reduced rimpull and reduced acceleration and therefore, longer cycle times and lower productivity

3. Truck box is optimally sized based on density of material to optimize payload.

4. Payload (Gross Vehicle Weight (GVW) minus Empty Vehicle Weight (EVW equals Maximum Payload) follows the 10/10/20 rule (often misunderstood, the 10/10/20 rule means that 10% of the time, the truck can be 10% overloaded, and 0% of the time can the truck be 20% loaded).

Based on the “perfect” environment above, this means that anytime you deviate away from the conditions, the truck is performing at a level slightly less than it’s potential. Translated into production/savings, it means that the changes you make to ensure proper payload weight/distribution and well-maintained haul roads will enable the following:

  • Faster Cycle Times à Increase Productivity
  • Extended Drive Train, Suspension, Frame & Tire Life[ii] à Lower Operating Cost & Increased Machine Availability
  • Reduced Fuel Consumption à Lower Operating Cost
  • Reduce Operator Fatigue à Promotes Safety
  • Increased haul road maintenanceà Maximize Support Equipment Utilization

The information above begs two questions:

1. What technology tools can we use to help us monitor and analyze the conditions?

2. How do we improve our conditions to better reflect design parameters?

To answer the questions, I will first introduce a tool, then explain how this tool can help in each of the four (4) operating conditions of the “perfect” environment.

Caterpillar has designed a system called RAC[iii] (Road Analysis Control), which is an on-board information provider source that is integrated with VIMS (Vehicle Information Management System). RAC quantifies and monitors haul road conditions and identifies events at a range of severity that are damaging to the following:

  • Machine Performance
  • Component and Frame Life
  • Availability / Utilization
  • Machine Productivity

The RAC warnings can be local to the truck only with real-time feedback to the operator; or with a wireless system in the pit, this information can be transported back to the dispatcher, engineer, or supervisor. Note: If you want to utilize the data back at the office, you will need proprietary desktop Caterpillar software.

To monitor & improve road conditions: Using RAC and activating a GPS unit with your dataset, you can then start to identify where haul road problems should be avoided/corrected and better allocate your resources – grader, operators, and training dollars. Also, you can respond quicker to making repairs to the roads. With improved pit planning, haul profiles and haul road maintenance, you can see increased truck speeds (if you are not already at maximum for the corresponding road grade).

To monitor and improve load distribution: Because RAC is constantly measuring the strut pressures for correct load distributions, you can determine when the truck is not at 33%/66% front/rear and 50%/50% right/left loading. You can then identify the shovel operators that need further training.

To monitor and improve payload optimization: Within VIMS, there is a function called TPMS (Truck Payload Monitoring Systems). When the struts are property calibrated (I would advise adding that as a maintenance item at the 500 hour PM (Preventative Maintenance)), TPMS will accurately provide the payload. This data is stored and shown locally and/or streamed back wirelessly to the office. Again, this VIMS and TPMS data requires proprietary Caterpillar software to decode, review and analyze.

You can then create charts with this data to see what the payload % curve/histogram looks like. With that, you can again spot-train shovel operators. When loaded properly, you should maximize GVW minus EVW of your equipment (see spec sheets for GVW and EVW).

*Depending if you are over-trucked or under-trucked and many other parameters such as cycle time, commodity materials grade, etc., it may or may not be worth it for the shovel to engage in a partial bucket to bring the truck up to maximize payload. This is why shovel/truck pairing is so important when purchasing equipment during the capEX phase. Do the calculations to see what it shows on paper.

To monitor and improve truck box design: To review your truck box, first make sure it is loaded correctly: to avoid spillage, there should be slight extra room on the left, right and rear of the truck box. I have conventionally used 1’/1’/1’ when contributing to training materials for shovel operators when they load a truck. This could change from site to site depending on uphill loaded road grade.

If you are loading the truck properly and your scales are calibrated, but you are still not able to maximize payload (GVW minus EVW), then consider a new truck box design (lighter material/shorter life but higher payload). Do the cost analysis to see if the shorter component life is worth the higher payload (at commodity pricing currently, the payback is generally there).

If your trucks are constantly spilling but the truck scales say that you are not overloaded, then consider installing hungry boards on the side to increase the carrying volume of the box. Or engage in a redesign of the box to increase volume whilst maintaining the same box metal/liner weight.

Lastly, as with all technologies, its success is based on the users. Unless operators and/or downstream users of this information are educated and unless there is a process to create/fix the source of the alarms, the technology will not yield cost savings and other benefits for the operation.

Would love to hear everyone’s feedback on this issue; your comments are always appreciated!

 



[i] Disclaimer: By focusing on Caterpillar equipment and technology as examples, I am in no way endorsing Caterpillar over any other OEM/OTM nor have I received any compensation at current time of writing for my blog entry from any OEM/OTM for this blogpost.

 

[ii] Quick cost analysis?on cost savings by increasing tire life by 10% (from 7000hrs to 7700hrs). The referenced cost of tires are estimates only, based on a 46/90/R57 tire.

–       New Tires for 1 Truck: 6 tires @ $40,000ea = $240,000?for one truck

–       An extra 700 hours generates tire savings per hour = $3.12 ($34.29 – $ $31.17)

–       365 days per year x 24 hours per day x 90% availability x 90% utilization = 7096 equipment hours per year

–       Savings per truck per year = 7096 equipment hours per year x $3.12 savings per equipment hour = $22,138

–       Fleet Savings per year = $22,138 x 30 average trucks per fleet = $664,148/year

 

With simple reallocation of mine resources to prioritize haul road maintenance and training for proper load distribution, a 10% increase in tire life leads to an easy $665k savings per year for the fleet of 30 trucks at this imaginary mine. And this does not even account for less frame cracks/welding downtime, or longer major component life due to lower vibrations!

 

[iii] A quick note on availability of RAC: It is not available in all Caterpillar equipment nor is it a standard option on the equipment that does offer RAC. For some of your older equipment, they may have a retrofit kit. For details, contact your local Caterpillar dealer.

 

  • Billden664

    Nice Vivien!

  • Ruth

    Difficult to read with grey font color, the contrast is too low. Can you change it to black?

    • Vivien

      Sorry Ruth – I am using a wordpress theme and don’t know how to change font colors :(

  • Jack

    I cannot find how you get 10% increase in tyre hours,  We consider that we can save most opencast mines around 20%
    Jack

    • vivien214

      Hello Jack,

      10% is only an estimate. Each mine will vary depending on what their baseline is and how much change they implement up to diminishing returns.
      Cheers!
      Vivien

      Sent from my BlackBerry device on the Rogers Wireless Network

      • Jack

        Hello Vivien,
        On inspecting the tyre dumps of several mines in South Africa we found that we could repair and put back into service at least 30% of tyres that had been deemed un-repairable but big opposition from tyre contractors on site. We understand that a mine’s tyre budget is 5% of its haul costs and we could save them 20% of that.
        Regards
        Jack

      • Jack

        Hello Vivien,
        On inspecting the tyre dumps of several mines in South Africa we found that we could repair and put back into service at least 30% of tyres that had been deemed un-repairable but big opposition from tyre contractors on site. We understand that a mine’s tyre budget is 5% of its haul costs and we could save them 20% of that.
        Regards
        Jack

  • Pat Rich

    Interesting product , the problem is that it doesn,t take into effect were the tire hits the ground , unless your monitoring your tires air pressure and temperature ,your only covering part of the problem , rolling resistance and low air pressure , increases fuel consumption and tire usage , a tire 10% low in pressure burns 2 to 3 % more fuel and wears tires 9 to 12% faster.A low tire also increases the temperature of  the tire ,which can end up in tire failure .If your going to use the system you also need a Tire Monitoring System.
    Pat

    • Vivien

      Hi Pat,
      Great comments! Absolutely. You also need to make sure your struts are calibrated, otherwise the readings are not accurate to a degree where an action item should be posed based on the feedback. Do you have any tire monitoring systems that you have used and found success in the past?
      Vivien

    • Eking

      Hi Pat and Vivien,
      As Vivien asked do you have any tire monitoring system that you used or you can suggest. I am looking for a tire monitoring system that would be benefical for our project. A programme which we can put all tire data such as operating hr, model, type etc. We are using seperated excel sheets and access links to monitoring the tirelife. It is difficult to operate such a system and takes a lot of time.

      Vivien, an article or study for tire-life / tire-management system would be great.

      Thanks.

      • Patr

        Rimex , Michelin have systems, as well as AM Bromley out of the UK , I would contact Mandy Bromley at mandy.bromley@ambromley.co.uk

        • vivien214

          Thanks Pat and Eking!
          Eking: I will add tires to my list. I have a few articles in waiting right now. Thanks for the suggestion:)
          Sent from my BlackBerry device on the Rogers Wireless Network

  • Shanthi16

    Hi,
    I would like to know moe about open pit mines, could you please provide your contact information or mail me to shanthi16@gmail.com
    thanks
    s@gmail:disqus 

    • Vivien

      Hello – what can I help you with with respect to open pit mines?

  • Patrick Schoutens

    Great article, i hop e you consider additional discussions on the subject, particularly haul road maintenance issues, fuel savings and CER as a result of improved wearing course construction and maintenance. I would be keen to discuss the matter further with you, our biggest challenge as a company is nurturing the mining companies toward BAT such as this and moreover getting them to stick with it over the longterm. Management change is imminent therefore we need to continually revise and improve the model such as yours to incorporate a simple yet sustainable model which they can adapt and monitor the annual improvement.

    • Vivien

      Hi Patrick, Thanks for the message. I do plan on future articles around those topics especially fuel savings as a result of not just road maintenance but also operator practice, etc. If you would like to discuss this further, please e-mail me. You can find my contact info under Abstract. Cheers! Vivien

  • http://twitter.com/bobbymetzinger Bobby Metzinger
    • Vivien

      Hi Bobby,
      I did an extensive due diligence as part of an RFP when I worked for AngloGold. Unfortunately this was in 2009 and the products have evolved since then. For example, Modular has a new platform/hub, Cat has completely redesigned the entire line of products and added much engineering efforts, ETC. Right now, most of my knowledge of the systems come from seeing them at trade shows and talking to dispatch coordinators who are using one system or another. 
      Vivien

      • Kwun

        Hi Vivian,
        I’m a senior student at CSM for mining….I’m looking at alternative ways to monitor haul road conditions, can I email you personally?

  • Adamg

    Hello Eking, have a look at Advantagepressurepro.com.  This is a cost effective, simple to use with no ongoing costs.  I can help with you with more info, find me on tyresafe.com.au.  Adam G

  • Todd Richard Myers

    With regards to matching, it is esential that there is a good relationship between production and maintenance as well when decisions are made.

    I’ve seen an occassion where a combination went from a perfect three pass match (double side loading on wide benches so three passes wasn’t a big issue as there should have been minimal or no truck exchange time) to 3.5 passes because maintenance decided the dipper needed to be smaller because the shovel was getting cracks in the boom.

    No analysis was undertaken of the costs of boom repair (relatively minimal) compared to the huge losses to production. Not to mention the increased variability in truck payloads which couldn’t have been good for maintenance.

    • Vivien

      Well said!