1
Designing and Benchmarking Mine Designing and Benchmarking Mine Roads for Safe and Efficient HaulageRoads for Safe and Efficient Haulage
Roger ThompsonRoger ThompsonAlex Alex VisserVisser
Departments of Mining and Civil & BioDepartments of Mining and Civil & Bio--systems systems EngineeringEngineering
University of Pretoria, South AfricaUniversity of Pretoria, South Africa
Aim of PresentationAim of Presentation
An overview of industry An overview of industry ‘‘bestbest--practicepractice’’in haulin haul-- or roadway designor roadway designAs a basis for reducing accident As a basis for reducing accident potential associated with poorly potential associated with poorly design roadsdesign roads
2
Scope of Scope of PresentationPresentation
IntroductionIntroductionMine Road Design CategoriesMine Road Design CategoriesTransport and Mining Accident StatsTransport and Mining Accident StatsMine Haul Road Safety Audit SystemMine Haul Road Safety Audit SystemConclusionsConclusions
Introduction Introduction --application scenarioapplication scenario
Historically, mine road design was empirical, adHistorically, mine road design was empirical, ad--hoc and not always focused on the accident hoc and not always focused on the accident potential of poor design workpotential of poor design workTraffic volumes are low, but highly variable over Traffic volumes are low, but highly variable over an extensive network of unpaved roadsan extensive network of unpaved roads
3
Historically, mine road design was Historically, mine road design was empirical, adempirical, ad--hoc and not always focused hoc and not always focused on the accident potential of poor design on the accident potential of poor design workwork
Introduction Introduction --application scenarioapplication scenario
Components of a mine road design Components of a mine road design include;include;
geometric design (alignment)geometric design (alignment)structural design (thickness and strength)structural design (thickness and strength)functional design (surfacing)functional design (surfacing)maintenance management (blading, grading)maintenance management (blading, grading)
Mine Road DesignMine Road DesignCategoriesCategories
Functional design
BA
SIC
DA
TA
Structural design
Maintenance Management
System
Dust Palliative Management
Within limits –no treatment required
Chemicalpalliation
Water-based spraying
Modify wearing courseselection
Dust ModelPalliative
Performance Model
Geometric design
Functional design
BA
SIC
DA
TA
Structural design
Maintenance Management
System
Dust Palliative Management
Within limits –no treatment required
Chemicalpalliation
Water-based spraying
Modify wearing courseselection
Dust ModelPalliative
Performance Model
Geometric design
4
Integrating the Categories of a Haul Integrating the Categories of a Haul Road DesignRoad Design
Functional design
BA
SIC
DA T
A
Structural design
Maintenance Management
System
Dust Palliative Management
Within limits –no treatment required
Chemicalpalliation
Water-based spraying
Modify wearing courseselection
Dust ModelPalliative
Performance Model
Geometric design
What are the safety critical issues in What are the safety critical issues in road design?road design?
Functional design
BA
SIC
DA T
A
Structural design
Maintenance Management
System
Dust Palliative Management
Within limits –no treatment required
Chemicalpalliation
Water-based spraying
Modify wearing courseselection
Dust ModelPalliative
Performance Model
Geometric design
5
What are the safety critical issues in What are the safety critical issues in road design?road design?
Functional design
Geometric design
Horizontal design and alignment –sight distances
Horizontal design Horizontal design and alignment and alignment ––sight distancessight distances
Vertical design and alignment
Vertical design and Vertical design and alignmentalignment
Berm designBermBerm designdesign Wearing course selection
Wearing course Wearing course selectionselection
Wearing course dust treatments
Wearing course dust Wearing course dust treatmentstreatments
Skid resistance and loose material -
stoniness
Skid resistance and Skid resistance and loose material loose material --
stoninessstoniness
Structural design
Geometric DesignGeometric Design
Use a structured approach to geometric Use a structured approach to geometric design;design;
Firstly, a set of mine geometric design Firstly, a set of mine geometric design standardsstandardsSecondly, the conceptual designSecondly, the conceptual designFinally, the Finally, the ‘‘asas--builtbuilt’’ designdesign
6
Conceptual road vertical and horizontal layout
Conceptual Conceptual road vertical road vertical and horizontal layoutand horizontal layout
Truck minimum braking distances (unassisted)Truck typical speeds up- and down-gradeTruck sight distance requirements
Truck minimum braking distances (unassisted)Truck typical speeds up- and down-gradeTruck sight distance requirements
Lay out the road according to 9-11% max sustained gradeAssume initial width of road 4,5x width of truck including berms and drainsHighlight location of
SwitchbacksCurves (horizontal and vertical)Intersections
Lay out the road according to 9-11% max sustained gradeAssume initial width of road 4,5x width of truck including berms and drainsHighlight location of
SwitchbacksCurves (horizontal and vertical)Intersections
Examine conceptual design following vertical and horizontal alignment requirements
Examine conceptual Examine conceptual design following design following vertical and horizontal vertical and horizontal alignment alignment requirementsrequirements
Locate switch-backs on section of road with no vertical gradesLocate switch-backs on section of road with no vertical grades
Intersection designIntersection designIntersection design
Drainage designDrainage designDrainage design
Locate intersections on level with adequate sight, curves and run-out.Locate intersections on level with adequate sight, curves and run-out.
Design drainage system, especially road-side, culvert location, switchback and intersection drainage.
Design drainage system, especially road-side, culvert location, switchback and intersection drainage.
Separate vertical and horizontal curves where possibleSeparate vertical and horizontal curves where possible
Horizontal design and alignment
Horizontal design and Horizontal design and alignmentalignment
Vertical design and alignment
Vertical design and Vertical design and alignmentalignment Establish minimum vertical curve lengths
based on change in grade (%) or headlight distance for sag curves, for minimum stopping distance
Establish minimum vertical curve lengths based on change in grade (%) or headlight distance for sag curves, for minimum stopping distance
Establish minimum horizontal curve lay-back based on braking distanceEstablish minimum horizontal curve lay-back based on braking distance
Establish optimum grade 9-11%,.Establish optimum grade 9-11%,.For every 1% increase in rolling resistance over 2%, reduce optimum grade by 1%
For every 1% increase in rolling resistance over 2%, reduce optimum grade by 1%
Establish cross-fall value or camber (2-4%). Laden lane at ‘uphill’ side of cross-fall.
Establish cross-fall value or camber (2-4%). Laden lane at ‘uphill’ side of cross-fall.
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Establish width of road according to;Truck widthTraffic (1-2 lanes)Safety berm at outslope and centre of road
Establish width of road according to;Truck widthTraffic (1-2 lanes)Safety berm at outslope and centre of road
Establish run-outs based on curve super-elevation, cross-fall and camber.Establish run-outs based on curve super-elevation, cross-fall and camber.
Berm designBermBerm designdesign
Design berms (median and outslope) with largest truck and speed in mind.Design berms (median and outslope) with largest truck and speed in mind.
Establish minimum horizontal curve radius based on speed of truck and super-elevation (5% max)
Establish minimum horizontal curve radius based on speed of truck and super-elevation (5% max)
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Final geometric design
Final geometric Final geometric designdesign
Drainage re-evaluationDrainage reDrainage re--evaluationevaluation
Horizontal design and alignment
Horizontal design and Horizontal design and alignmentalignment
Vertical design and alignment
Vertical design and Vertical design and alignmentalignment Establish minimum vertical curve lengths
based on change in grade (%) or headlight distance for sag curves, for minimum stopping distance
Establish minimum vertical curve lengths based on change in grade (%) or headlight distance for sag curves, for minimum stopping distance
Establish minimum horizontal curve lay-back based on braking distanceEstablish minimum horizontal curve lay-back based on braking distance
Establish optimum grade 9-11%,.Establish optimum grade 9-11%,.For every 1% increase in rolling resistance over 2%, reduce optimum grade by 1%
For every 1% increase in rolling resistance over 2%, reduce optimum grade by 1%
Establish cross-fall value or camber (2-4%). Laden lane at ‘uphill’ side of cross-fall.
Establish cross-fall value or camber (2-4%). Laden lane at ‘uphill’ side of cross-fall.
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Establish width of road according to;Truck widthTraffic (1-2 lanes)Safety berm at outslope and centre of road
Establish width of road according to;Truck widthTraffic (1-2 lanes)Safety berm at outslope and centre of road
Establish run-outs based on curve super-elevation, cross-fall and camber.Establish run-outs based on curve super-elevation, cross-fall and camber.
Berm designBermBerm designdesign
Design berms (median and outslope) with largest truck and speed in mind.Design berms (median and outslope) with largest truck and speed in mind.
Establish minimum horizontal curve radius based on speed of truck and super-elevation (5% max)
Establish minimum horizontal curve radius based on speed of truck and super-elevation (5% max)
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Where pit geometry does not allow for minimum requirements, apply speed limit to each curve not meeting requirements
Final geometric design
Final geometric Final geometric designdesign
Drainage re-evaluationDrainage reDrainage re--evaluationevaluation
7
Geometric DesignGeometric Design
Well documented Well documented –– but take special but take special care with;care with;
Ramps Ramps –– width, junction visibility, spillage width, junction visibility, spillage and drainageand drainage
Geometric DesignGeometric Design
Well documented Well documented –– but take special but take special care with;care with;
Ramps Ramps –– width, junction visibility, spillage width, junction visibility, spillage and drainageand drainageSwitchbacks and curves Switchbacks and curves –– larger radius , larger radius , supersuper--elevated and sight / stopping elevated and sight / stopping distancesdistances
8
Geometric DesignGeometric Design
Well documented Well documented –– but take special but take special care with;care with;
Ramps Ramps –– grade breaks and max productive grade breaks and max productive total resistance (grade + rolling) total resistance (grade + rolling) Switchbacks and curves Switchbacks and curves –– larger radius , larger radius , supersuper--elevated and sight / stopping elevated and sight / stopping distancesdistances
Geometric DesignGeometric Design
Berms Berms –– especially centre especially centre bermsberms –– large large enough to arrest vehicle enough to arrest vehicle –– but visibility but visibility issues for smaller vehiclesissues for smaller vehicles
9
Geometric DesignGeometric Design
BermsBerms –– especially centre especially centre bermsberms –– large large enough to arrest vehicle enough to arrest vehicle –– but visibility but visibility issues for smaller vehiclesissues for smaller vehiclesDrainage Drainage ––crosscross--fall or camber and fall or camber and roadside drainage ditchesroadside drainage ditches
Geometric DesignGeometric Design
BermsBerms –– especially centre especially centre bermsberms –– large large enough to arrest vehicle enough to arrest vehicle –– but visibility but visibility issues for smaller vehiclesissues for smaller vehiclesDrainage Drainage ––crosscross--fall or camber and fall or camber and roadside drainage ditchesroadside drainage ditches
10
Geometric DesignGeometric Design
Make sure that what you have Make sure that what you have designeddesigned is is built and maintained correctlybuilt and maintained correctlyMake use of signage to assist grader and Make use of signage to assist grader and truck operators to make maximal use of the truck operators to make maximal use of the roadroad
Structural DesignStructural Design
Load carrying capacity of the road. Design Load carrying capacity of the road. Design for;for;
Better pavement response to applied loadsBetter pavement response to applied loadsReduced deflection on surface and Reduced deflection on surface and deformation in subdeformation in sub--grade or ingrade or in--situsitu
= Better directional stability of truck= Better directional stability of truck
11
Structural DesignStructural DesignCase StudyCase Study
Structural design comparisons0
250500750
1000125015001750200022502500
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Vertical (micro) strain in pavement
New
Des
ign
Laye
r De
pths
(mm
)02505007501000125015001750200022502500
Old Design New Design
Old
Des
ign
Laye
r De
pths
(mm
)
W/course
Fill layer
Layer 3In-situ
Selectedblasted waste
rock
Layer 3In-situ
W/course
Wearing course
Base
In-situ (soft)
Wearing course
Base
In-situ (soft)
Wearing course
Base
In-situ (soft)
Wearing course
Base
In-situ (soft)
Wearing course
Base
In-situ (soft)
Wearing course
Base
In-situ (soft)
Functional DesignFunctional Design
Wearing course material selection. Design Wearing course material selection. Design for;for;
Reduced wearing course Reduced wearing course ‘‘defectsdefects’’ –– especially especially dustiness and loose materialdustiness and loose materialReduced deterioration rates and maintenance Reduced deterioration rates and maintenance frequencyfrequency
12
Functional DesignFunctional DesignWearing Course Selection
0
50100
150
200
250300
350
400
0 5 10 15 20 25 30 35 40 45 50
Grading Coefficient
Shr
inka
ge P
rodu
ct
.
Recommended (1) Recommended (2)
Dustiness Slippery when wet
Loose materialLoose stonesTyre damage Corrugates
050
100150200250300350400450500550
0 10 20 30 40 50
Grading coefficient
Shrin
kage
pro
duct
.
DustinessWet skid resistance
Loose stoniness
Corrugations
Loose material
Dry skid resistance
12
Practical Practical ApplicationApplication
13
050
100150200250300350400450500550
0 10 20 30 40 50
Grading coefficient
Shrin
kage
pro
duct
.
Dustiness
Loose stoniness
Dry skid resistance
1
Practical Practical ApplicationApplication
Practical Practical ApplicationApplication
Consider the use of dust palliatives to Consider the use of dust palliatives to improve wearing course performance BUT;improve wearing course performance BUT;
Will not Will not ‘‘fixfix’’ an inherently poorly design road an inherently poorly design road (expensive)(expensive)Require dedicated and modified road Require dedicated and modified road management approach management approach –– one product doesnone product doesn’’t t fit all types of applicationsfit all types of applications
14
Transport & MiningTransport & MiningAccident StatisticsAccident Statistics
About half of all attributable transport accidents are About half of all attributable transport accidents are roadroad--design related;design related;
Geometric design problemsGeometric design problemsFunctional design problemsFunctional design problemsHuman errorHuman errorNonNon--standard practicesstandard practices
Percentage of road design factors implicated in attributable T&M accidents
Human Error14%
Geometric10%
Functional8%
Practices9%
Not attributable53%
Other issues5%
Road design related accidents
47%
Maintenance1%
15
No formal design
Ad-hoc design
Generic design
Formal design
High accident potential –
‘unforgiving’conditions
Heightened safety –
accommodate human error
Human error and non-standard acts 47%
Road design factors 43%
Vehicle mechanical and 'other' factors 10%
19%25%
14%3%
1,5%4%1,5%
Heightened safety –
accommodate human error
16
Mine Haul Road Mine Haul Road Safety AuditsSafety Audits
The objectives of using a safety audit systems are;The objectives of using a safety audit systems are;To provide a structured appraisal of potential safety To provide a structured appraisal of potential safety problems for roadproblems for road--users and road operatorsusers and road operatorsTo ensure that suitable measures for the problem elimination To ensure that suitable measures for the problem elimination are fully evaluated and appliedare fully evaluated and applied
Mine Haul Road Mine Haul Road Safety AuditsSafety Audits
The benefits of using a safety audit systems are;The benefits of using a safety audit systems are;A potential reduction in the number and severity of T&M A potential reduction in the number and severity of T&M accidentsaccidentsHaul road safety is given greater prominence in the minds of Haul road safety is given greater prominence in the minds of roadroad--user, operators and designersuser, operators and designersThe need for costly remedial work is reduced (if the audit is The need for costly remedial work is reduced (if the audit is implemented at the design stage)implemented at the design stage)
17
Mine Haul Road Mine Haul Road Safety AuditsSafety Audits
Audit StageD
esig
n C
ompo
nent
A
sses
sed
Feasibility
General Topics
General Design Issues
Alignment
Junctions
Environmental
Road Users
Mine Haul Road Mine Haul Road Safety AuditsSafety Audits
Audit Stage
Des
ign
Com
pone
nt
Ass
esse
d
Draft Design
General Topics
General Design Issues
Alignment
Junctions
Environmental
Road Users
Signs and lighting
Other
18
Mine Haul Road Mine Haul Road Safety AuditsSafety Audits
Audit StageD
esig
n C
ompo
nent
A
sses
sed
Detailed Design
General Topics
General Design Issues
Alignment and cross section
Junctions
Environmental
Road Users
Signs and lighting
Physical Objects
Construction
Other
Mine Haul Road Mine Haul Road Safety AuditsSafety Audits
Audit Stage
Des
ign
Com
pone
nt
Ass
esse
d
Pre-Opening
General Topics
General Design Issues
Alignment and cross section
Junctions
Road Users
Signs and lighting
Physical Objects
Maintenance
Finishing
Training road-users
Other
19
Mine Haul Road Mine Haul Road Safety AuditsSafety Audits
Audit StageD
esig
n C
ompo
nent
A
sses
sed
Existing roads
General Topics
General Design Issues
Alignment and cross section
Junctions
Road Users
Signs and lighting
Physical Objects
Maintenance
Training road-users
Road-user feedback
20
Practical Practical ApplicationsApplications
ID the ID the ““KPSKPS”” –– KKey ey PPerformance erformance SSegments on egments on your road network;your road network;
SafetySafety--critical segments critical segments –– intersections, ramps, intersections, ramps, switchbacks, etc.switchbacks, etc.High speed high tonnage roadsHigh speed high tonnage roads
Prioritize remediation on these segmentsPrioritize remediation on these segments
Practical Practical ApplicationsApplications
Visual inspections Visual inspections –– mark roads where maintenance mark roads where maintenance should be done with red, yellow or green cones should be done with red, yellow or green cones ––prioritize.prioritize.Record maintenance intervention (what done) and Record maintenance intervention (what done) and frequencies (how often) per segment frequencies (how often) per segment –– establish a establish a rehabilitation schedule rehabilitation schedule –– prioritize BUTprioritize BUT……..
21
Practical Practical ApplicationsApplications
Why does the segment have safetyWhy does the segment have safety--critical issues?critical issues?Poor design and / or build specs;Poor design and / or build specs;
GeometricsGeometricsStructure (layer works and materials)Structure (layer works and materials)Functional (wearing course)Functional (wearing course)
Investigate the rootInvestigate the root--cause of the undercause of the under--performance performance beforebefore deciding on a remediation deciding on a remediation strategystrategy
ConclusionsConclusions
The ProblemThe Problem
Poor or no haulPoor or no haul-- and roadway design often leads and roadway design often leads to otherwise avoidable T&M accidentsto otherwise avoidable T&M accidents
22
ConclusionsConclusions
The ChallengeThe Challenge
How to design a haulHow to design a haul-- or roadway that is more or roadway that is more accommodating for driver error?accommodating for driver error?How to benchmark the suitability of existing How to benchmark the suitability of existing roads?roads?How to remediate haul road problems?How to remediate haul road problems?
ConclusionsConclusions
The Way AheadThe Way Ahead
Training mine staff in the principles of good road Training mine staff in the principles of good road designdesignThe use of more formal geometric and functional The use of more formal geometric and functional design procedures to assist in eliminating design procedures to assist in eliminating accidentsaccidentsThe use of a haul road design audit system to The use of a haul road design audit system to evaluate proposed or current road design and evaluate proposed or current road design and safety performancesafety performance
23
ConclusionsConclusions
Additional ResourcesAdditional Resources
TechnologyTechnologywww.advminingtech.com.auwww.advminingtech.com.auwww.acumine.comwww.acumine.comhttp://jnbqp1.corporate.aaplc.com/hme (by invitation)http://jnbqp1.corporate.aaplc.com/hme (by invitation)
Road design guidelines and performance Road design guidelines and performance benchmarkingbenchmarking
www.up.ac.za/academic/mining/research/research_frame.htmwww.up.ac.za/academic/mining/research/research_frame.htm
Road design and management training coursesRoad design and management training courseswww.ceatup.comwww.ceatup.com
Acknowledgements Acknowledgements
Parts of the work described in this paper was carried out as parParts of the work described in this paper was carried out as part of the other t of the other mines research program of the Mine Health and Safety Council Safmines research program of the Mine Health and Safety Council Safety in ety in Mines Research Advisory Committee. The authors gratefully acknoMines Research Advisory Committee. The authors gratefully acknowledge the wledge the financial assistance and support received from the SIMRAC and SIfinancial assistance and support received from the SIMRAC and SIMOT MOT committees.committees.
Details may be found from;Details may be found from;www.simrac.co.za/report/Reports/thrust5/oth308/oth308.htm. www.simrac.co.za/report/Reports/thrust5/oth308/oth308.htm.