Transportation Association of Canada’s

Guide to Load Management for

Low Volume Roads

Weak Pavement Structures

Presented by - Gary St. Michel

February 2017

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)

Ania Anthony – Saskatchewan Highways

Dr. Ahmed Shalaby – University of Manitoba

Dr. Leonnie Kavanagh – University of Manitoba

Special Thanks

Identify Current Practices

Project Initiation

Literature Search - Available Technology

Synthesize Current Practices/Available

Technology

Develop Recommendations and

Produce Report

Basic Methodology

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

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

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

Survey

• Seven Main Topics

• Total of 22 Questions

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

Literature Search

63 Documents

Reviewed,

Synthesized and

Referenced

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

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.

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

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.

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.

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).

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

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.

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.

Economic Aspects Specific to

Low Volume Roads Weak Pavement Structures

Transport Cost Analysis

Decision Support Framework

Deflection/Loading versus Weight Limit

Transport Cost Analysis

Maintenance Cost Calculation

Additional Freight Cost Calculation

Upgrade Cost Calculation

Making the Load Management Decision

Load Management During Spring Thaw

Load Management of Sub-standard Pavements

Load Management for Frozen Pavements

Questions?