Optimising Gravel Road Maintenance Strategies. Presenter: Gerrie van Zyl

Transcription

1 Optimising Gravel Road Maintenance Strategies Presenter: Gerrie van Zyl

2 Scope Introduction Road management systems Utilising information to improve maintenance strategies Blading optimisation process Conclusion August 3, 2009 Slide 2

3 Integrated Road Management Systems ROAD REFERENCING SYSTEM NETWORK INTEGRATION MODULE ROAD PROCLAMATION SYSTEM TRAFFIC SURVEILLANCE SYSTEM PAVEMENT MANAGEMENT SYSTEM UNSEALED ROAD MANAGEMENT SYSTEM BRIDGE MANAGEMENT SYSTEM

4 ACTIVITY FLOW IN ROAD MANAGEMENT Detailed investigation and design Project Planning Maintenance/ rehabilitation or upgrading Inventory DATA MANAGEMENT Location referencing Condition monitoring Condition description Analyses Deterioration Measure selection Fund allocation Prioritisation & Optimisation GvZ 2008 Final prioritisation Presentation to Management 4

5 Location Referencing and Inventory Road No Start & End Description Km GPS Attributes Category Surface type Geometry Features Etc.

6 ACTIVITY FLOW IN ROAD MANAGEMENT Maintenance/ rehabilitation or upgrading Inventory Condition survey Detailed investigation and design Project Planning Fund allocation DATA MANAGEMENT Location referencing Condition description Deterioration modelling Prioritisation & Optimisation GvZ 2008 Final prioritisation Presentation to Management 6

7 Condition Assessment Formalised visual assessment (TMH12) Roughness Material thickness and properties Insitu strength (DCP) Additional information Traffic Climate Topography August 3, 2009 Slide 7

8 Visual assessment Roughness Layer thickness Material properties DCP Unit costs Condition assessment August 3, 2009 Slide 8

9 DCP testing LAYER-STRENGTH DIAGRAM km 3.4 TR22/ Inadequate strength

10 Condition description Condition description (Network) 10

11 Reporting Condition trends 100% Very Poor Poor Fair Good Very Good 80% 60% 40% 20% 0%

12 Reporting August 3, 2009 Slide 12

13 Project Control Module Project Activity Cost Analysis 12.8% Breaking Down Material 34.4% Transport & Tipping

14 Gravel Loss Function of: Material properties Climate Traffic Construction Blading frequency Calculate remaining life Minimum thickness Gravel loss (mm) DR1303( ) Time after construction (years) Actual HDM4 TRH20 August 3, 2009 Slide 14

15 PERFORMANCE MONITORING Visual assessment of distress type Roughness measurement Gravel loss and shape change Structural capacity Change in material properties DR Relative Height Offset (m) 2.25 Right Center 2.25 Left km1.30 km1.28 km1.26 km1.24 km1.22 km1.20 Stake Value

16 Material information availability TRH 20 Classification Shrinkage product A Erodible Ravel & Corrugate D Slippery Good (Dusty) E Grading Coefficient B C Ravel Shrinkage product (Sp) = % linear shrinkage x % passing 0,425 mm sieve Grading coefficient (Gc) = ([% passing 26,5 mm % passing 2,0 mm]x % passing 4,75 mm) / 100

17 Materials Information System

18 Impact of different strategies Roughness deterioration 18

19 Light blading Remove cohesionless material Spread fine material (moist & slightly plastic)

20 OBSERVATIONS AND IMPLICATIONS No deterioration after blading at low roughness levels TR58/1: km : Roughness Deterioration (Model vs. Actual) Model prediction versus measured 5 Riding Quality (IRI) Years since construction Actual QI TRH20: Blading

21 Effect of regular light blading ROUGHNESS PROGRESSION MR 584 km QI Years Normal Maintenance Actual Roughness AADT = 86, 14% heavy Slide 21 August 3, 2009

22 CONCLUSIONS ON RESHAPING Reshaping more economic than continuous blading at high roughness levels MR276: km : Roughness Deterioration (Model vs. Actual) Actual QI HDM Adjusted Constr f=0.8 HDM Blading (normal compaction) R iding Quality (QI) Effect of reshaping (Adjusted model) AADT = 323, 19% heavy (2001) Years Since Construction AADT > 500 (2007)

23 SIMPLIFIED DECISION TREE FOR REMEDIAL MEASURES ACCESSIBILITY SAFETY GRADEABILITY MATERIAL THICKNESS POOR OK POOR OK GEOMETRY OTHER POOR OK ROCK or SAND OTHER POOR OK POOR OK POOR OK EXPOSED SUBGRADE YES ISOLATED NO YES ISOLATED NO YES ISOLATED NO YES ISOLATED SUBGRADE STRENGTH SURF DRAINAGE 1 st Level MEASURE 1-CONSTRUCT 1-CONSTRUCT 2-FORM & GRAVEL 3-GRAVEL 3-GRAVEL 3-GRAVEL 4-SPOT GRAVEL 4-SPOT GRAVEL 7-REWORK /GRAVEL 5-REWORK/ SPOT GRAVEL 8-REWORK 3-GRAVEL 11-SPOT GRAVEL/B LADING 6-SPOT GRAVEL 11-SPOT GRAVEL/BLADING 9-FORMING 10-RESHAPE 11-SPOT GRAVEL/BLADING 6-SPOT GRAVEL 9-FORMING August 3, 2009 OK 12-NOR BLADING Slide 23 NO YES ISOLATED NO POOR OK POOR OK POOR OK POOR OK POOR OK POOR OK POOR POOR POOR OK OK OK POOR OK POOR LEVEL OTHER LEVEL OTHER LEVEL OTHER LEVEL OTHER LEVEL OTHER 6-SPOT GRAVEL 4-SPOT GRAVEL/GRAVEL 4-SPOT GRAVEL/GRAVEL 3-GRAVEL 7-REWORK /GRAVEL 6-SPOT GRAVEL 10-RESHAPE 12-NOR BLADING 6-SPOT GRAVEL 9-FORMING 10-RESHAPE 12-NOR BLADING 9-FORMING 10-RESHAPE

24 August 3, 2009 Slide 24

25 Measure Selection Routine maintenance Scheduled maintenance Upgrading to surfaced/ seal August 3, 2009 Slide 25

26 Routine maintenance Light and heavy blading Maintain drainage systems Vegetation control Fence repair Signage maintenance Patching August 3, 2009 Slide 26

27 Periodic/ Scheduled Maintenance Forming? Gravelling or spot gravelling Reshaping Reworking Network level Panel Inspections Site verification Final prioritisation Fund availability - Work program Project level August 3, 2009 Slide 27

28 Blading optimisation Part of operational (day-to-day) Maintenance Management System

29 Balance between theory and practice?

30 Factors influencing blading program Funding Organisational policy (uitslaap), depots Effectiveness (Grader availability, working hours) Road condition, material and maintainability User requirements Methodology and operator abilities Emergencies August 3, 2009 Slide 30

31 Define network Define Uniform Maintenance sections Define Minimum & Appropriate LOS Feedback Determine minimum & appropriate blading frequency and adjust Determine Min & Appr. Blading type, Blade passes, Blade km/ maint sect per annum Determine/ Allocate Grader Productivity per road/ area Unit Costs Min Fund Required Appropriate Funding Requirement Fund allocation Combine maint sections to obtain balanced Distribution per Ward/ Maint Area Grader requirements Strategies Distribute blading requirements to balance cycles: Blading Schedules Recalculate affordable blading frequency per maintenance section Verify monthly program on site & issue

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34 Results after implementation Well defined monthly programs Major reduction in complaints Positive feedback from communities/ RU Ability to adjust blading programs with reduced/ increased funding Ability to manage emergency work

35 CONCLUSIONS Formalised systems essential Integration of systems Location referencing/ inventory Traffic Unsealed road management system Maintenance Management System Project Control System (Costs) Materials Information System Experimental data Strategic & tactical (Network) Operational level (Project) Blading optimisation (Process)

36 The way forward? August 3, 2009 Slide 36

37 Any questions?