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Transportation Association of Canada’s
Guide to Load Management for
Low Volume Roads
Weak Pavement Structures
Presented by - Gary St. Michel
February 2017
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Nova Scotia Transportation & Infrastructure Renewal (Adam Marlin, Keith Purdy)
New Brunswick Transportation and Infrastructure (James Hoyt)
Ministry of Transportation, Quebec (Guy Bergeron)
Ministry of Transportation, Ontario (Max Perchanok)
Saskatchewan Highways and Infrastructure ( Chair Ania M. Anthony)
Manitoba Infrastructure and Transportation (Said Kass, Alauddin Ahammed)
Alberta Transportation (Chuck McMillan, Marta Juhasz)
Government of the Northwest Territories (David Currie)
Yukon Department of Highways and Public Works (Muhammad Idrees)
Project Funding Partners (PSC)
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Ania Anthony – Saskatchewan Highways
Dr. Ahmed Shalaby – University of Manitoba
Dr. Leonnie Kavanagh – University of Manitoba
Special Thanks
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Identify Current Practices
Project Initiation
Literature Search - Available Technology
Synthesize Current Practices/Available
Technology
Develop Recommendations and
Produce Report
Basic Methodology
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1. Defining Low Volume Roads (LVR);
2. Defining Weak Pavement Structures (WPS);
3. Spring Weight Restrictions (SWR);
4. Winter Weight Premiums (WWP);
5. Response of Weak Pavement Structures to Axle Loads;
6. Load Management Practices (year round);
7. Economic Aspects Specific to LVRs.
Impact of tire design removed from scope prior to project commencement
Seven Basic Topics
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1. Synthesis of Current Practices (Survey)
2. Synthesis of Available Technology (Literature Search)
3. Best Practices Guide Lines (Recommendations)
4. Decision Support Framework (How to Guide)
Four Major Sections
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Section Contents
1 Summary and Recommendations
2 Introduction and Background
3 Synthesis of Current Practices
4 Synthesis of Existing and Emerging Technologies
5 Best Practice Guidelines
6 Decision Support Framework
7 Recommendations and Conclusions
8 References
Reporting
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Survey
• Seven Main Topics
• Total of 22 Questions
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Survey Respondents Organization Province/State Country
Alberta Transportation Alberta Canada
BC Ministry of Transportation and Infrastructure British Columbia Canada
Manitoba Infrastructure and Transportation (MIT) Manitoba Canada
New Brunswick Department of Transportation and Infrastructure New Brunswick Canada
DoT and Works - Newfoundland and Labrador Newfoundland/Labrador Canada
Nova Scotia Transportation & Infrastructure Renewal Nova Scotia Canada
Northwest Territories DoT Northwest Territories Canada
Ontario MTO Ontario Canada
PEI Transportation and Infrastructure Renewal Prince Edward Island Canada
Quebec MTQ Quebec Canada
Saskatchewan Highways and Infrastructure Saskatchewan Canada
Yukon Highways and Public Works Yukon Canada
Centre for Economic Development, Transport and the Environment for Lapland Lapland Finland
Finnish Transport Agency Finland Finland
Swedish Transport Administration Sweden Sweden
Connecticut DoT Connecticut USA
Minnesota DoT Minnesota USA
Montana DoT Montana USA
Ohio DoT Ohio USA
South Dakota DoT South Dakota USA
Washington State DoT WA USA
Wisconsin Department of Transportation Wisconsin USA
US Department of Agriculture - US Forest Service United States USA
+ 40 small agencies
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Literature Search
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63 Documents
Reviewed,
Synthesized and
Referenced
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Ania Anthony – Saskatchewan Ministry of Highways and Infrastructure
Allan Churko – Past Director, Saskatchewan Ministry of Highways and Infrastructure
Leonnie Kavanagh – Pavement Engineering Research Lead University of Manitoba
Donaldson McLeod – Public Works and Government Services Canada (retired)
Dave Palsat – Past Director, Alberta Transportation
Alan Reggin – Senior Pavements Engineer
Gary Ruck – Roadway Asset Management Systems Implementation
Ahmed Shalaby – Professor, Pavement Engineering, University of Manitoba
Gary St. Michel – Roadway Asset Management Specialist
Best Practices - Expert Panel
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Categories of Best Practices
Those that can be implemented now using current proven technologies or
methodologies;
Those that may soon be available – to be identified in the guidelines as
“Emerging” best practices;
The best practices a function of agency resources or agency size.
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The study determined that there was no basis for defining LVRs with
respect to load management. The best practice is to define roads
(whatever the volume), in terms of being “Susceptible to Damage”. In
other words the focus of this study is on WPS not LVR in isolation.
Low Volume Roads Definition
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Weak Pavement Structure Definition
The study concluded that the best practice definition of a weak pavement structure is a pavement structure that is:
Susceptible to undue damage, i.e., not structurally adequate to minimize the life-cycle costs;
And that this definition applies to all pavements not only pavements that
have low traffic from a geometric or safety perspective or load management perspective.
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Spring Weight Restrictions
At least four large agencies have conducted economic studies in an attempt to justify abandoning SWR.
Three of these jurisdictions found that there was a societal net financial benefit to removing the SWR on many of the WPS.
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Spring Weight Restrictions (cont’d)
The study concluded that:
The technology for relating frost depth recording instruments to weather station data is sufficiently advanced that frost depth can be reasonably accurately determined directly from appropriately located climate station data;
The various correlations between freezing index and frost depth or thawing index
and structural weakening are sufficiently accurate for determining the real time onset of thaw directly from a freeze-thaw index, except perhaps on very thin pavement structures, (such as may exist on forestry roads); and
The existing best practice for determining the amount of weight restriction remains direct deflection testing using Falling Weight Deflectometer (FWD).
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Winter Weight Premiums
The study concluded that allowing additional winter weight is dependent on three factors:
Vehicle capacity/safety; Bridge/Culvert load-bearing capacity; and Pavement-subgrade system strength increase due to deep
frost penetration;
Given the above, 10% increase is reasonable
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Response of Weak Pavement Structures
to Axle Loads
It was concluded that best practices are:
Develop models (either Empirical, Structured-Empirical or Mechanistic-Empirical, calibrated to local conditions), based on independent variables that may include:
Regional Climatic Zones; Drainage/Moisture Environment; and Truck Traffic.
Models should be based on an understanding of the failure mechanism; and Use FWD based deflection testing and associated truck loadings/volumes to forecast pavement damage.
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Load Management Practices
“While making load management practice (LMP) decisions based on purely economic factors is considered a best practice, there is concern that agencies may not have the direct funding to take the most economically advantageous course.”
Suggest that the economic analysis include:
Direct Agency costs (Maintenance, Rehabilitation, Strengthening);
Road User Costs;
Alternative Routing; and
Freight Costs – at reduced loads.
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Economic Aspects Specific to
Low Volume Roads Weak Pavement Structures
Transport Cost Analysis
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Decision Support Framework
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Deflection/Loading versus Weight Limit
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Transport Cost Analysis
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Maintenance Cost Calculation
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Additional Freight Cost Calculation
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Upgrade Cost Calculation
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Making the Load Management Decision
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Load Management During Spring Thaw
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Load Management of Sub-standard Pavements
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Load Management for Frozen Pavements
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Questions?