Mineravia Consulting
Mine Haul Roads


Functional design
&
sheeting material selection



The functional performance or 'trafficability' of the road is dictated to a large degree through the selection, application and management of the wearing course (sheeting or surfacing) material.
Poor functionality is often experienced as poor ride quality, excessive dust, increased tyre wear and damage, intensive road maintenance and an accompanying loss of productivity
Critically, rolling resistance increases due to surface deterioration and a well-selected surfacing material will minimise this and ensure safer, more cost-effective performance from your truck fleet



Technical Resources - Functional Design



Technical background to Surfacing Selection



Most surface mine operators agree good roads are desirable, but find it difficult to translate this requirement into an effective and responsive surfacing (sheeting or wearing course) material selection.

An overview of the wearing course material selection for mine haul road applications is discussed, together with appropriate wearing course material selection guidelines. Using material performance models, a typical application is presented.


click to download paper

Road Performance Assessment & Rating Scales



Download zipped files, extract to same folder and open spreadsheet in Excel.

Road performance and rolling resistance can be estimated from a qualitative visual evaluation of the key 'defects' influencing road condition are identified.

For each road defect, the product of defect degree (how bad) (measured on a scale of 1-5) and extent (how much) (measured on a scale of 1-5) are scored for each of these defects. The sum of the individual defect scores (degree x extent) gives the overall defect score which can be related to rolling resistance and functionality of the road.

The spreadsheet prompts for defect scoring based on visual examples of each defect and degree, then determines the rolling resistance representing the overall condition of the road.


click to download spreadsheet

Rolling Resistance Estimation from road rating assessment



Download and open spreadsheet in Excel.

Rolling resistance relates primarily to the key defects of potholes, corrugations, rutting, loose material and stoniness in or on the road. Using the rating system described above, the rolling resistance is determined by rating the key defects.

Repeating this process at regular intervals enables a deterioration rate to be determined and road maintenance (grading) scheduled at a point where rolling resistance becomes excessive (and the 'value' generated by reducing rolling resistance exceeds the 'cost' of the road maintenance activity itself.

More details can be found under 'Road Maintenance Management'.


click to download spreadsheet

rolling resistance estimation using wearing course and truck data



Download and open spreadsheet in Excel.

Rolling resistance at any point in time can also be determined for each haul road based on the sheeting material key parameters of

  • PI (plasticity Index),
  • CBR (California Bearing Ratio 4-day soak),
  • SP (shrinkage product) and
  • GC (grading coefficient).

When coupled with traffic volume (kt hauled per day) and truck speed, the rolling resistance progression can be estimated.

Rolling resistance progression is important in determining how your road sheeting responds to increasing truck traffic - and the basis for truck performance and productivity estimations.


click to download spreadsheet

Surfacing Selection tool



Download spreadsheet and open in Excel.
This tool prompts users for typical road indicator test results from which a sheeting materials suitability is determined in terms of the key parameters of

  • GC - grading coefficient, and
  • SP - shrinkage product.

Additionally, several other selection considerations are assessed and the user can also identify sheeting material mix specifications required to bring a surfacing back into the required specification (blending).


click to download spreadsheet

road surfacing skid resistance assessments



A common issue on gravel-surfaced mine haul roads is loss of control or uncontrolled vehicle movements due to skidding or sliding on slick road surfaces.

The friction supply, or ‘skid resistance’ of a mine haul road wearing course is critical to the safe operation of the road, but the variation of friction supply with wearing course material engineering or indicator properties is very site-specific.

This paper outlines the development of improved and validated unpaved mine road friction supply estimates, based on wearing course material specification, leading to improved predictive models of friction supply.

Current skid resistance testing and protocols have been developed by RSTS (Tulloch and Stoker) who also conduct on-site testing, and equipment and software solutions from (Friction-Plus app) developed by ADE Australia, or Vericom (USA).


click for Vericom click for overview to skid resistance assessment click to download paper click for ADE tools

. Mining Haul Roads .
Mineravia Consulting





PERTH, WA, AUSTRALIA

Pages dated: Sept 2023