How FWD Testing Helps Optimize Road Rehabilitation Budgets for Prairie Communities

Municipalities and transportation teams across the Prairies face increasing pressure to maintain their core public infrastructure with renewal budgets that have not kept pace with infrastructure aging. The largest and most visible component of core public infrastructure are road assets. Access to accurate pavement data can make planning easier, more predictable and more cost-effective.

This article explains how Falling Weight Deflectometer (FWD) testing helps Prairie communities stretch their budgets, identify effective rehabilitation treatments and plan long‑term infrastructure investments.

How Pavement Stress Affects Long‑Term Rehabilitation Planning

Roads across the Canadian Prairies support commercial transport, agriculture, intermunicipal travel and resource‑sector activity. These networks face structural stress from heavy traffic loads and wide seasonal temperature swings. For engineering teams responsible for maintenance planning, understanding pavement condition deterioration is essential. As a rule of thumb, pavement quality drops 40% during the first 75% of its life and then drops another 40% in only the next 12% of its life, which is colloquially refer as the death spiral. Treatment options made during the death spiral would typically cost on order of magnitude 4 or 5 times more than those made just a few years earlier.

With consistent FWD testing data, municipalities and transportation teams can monitor pavement structural quality, design efficient treatment strategies and prioritize projects that offer long‑term value.

What Is FWD Testing?

FWD testing is a non-destructive pavement assessment method that measures how the road surface deflects under a controlled load to evaluate structural capacity. This process simulates the impact of commercial vehicles and helps engineers determine the structural integrity of each pavement layer.

The FWD unit, consisting of a load plate assembly and associating data sensors, is mounted onto a trailer designed for easy transport using a light-duty vehicle. The FWD unit is brought to complete stop to perform the test. Traffic accommodations may be required. The FWD test consists of applying a known load to the pavement surface via a series of control drops and seismic sensors set at varying distance from the drop record the pavement’s deflection basin. 

The average time required to perform a single FWD test is under a minute. There is also the development of Fast Falling Weight Deflectometer (FastFWD) which replaced the hydraulic system in older FWD units with a single direct drive assembly which enables tests to be up to 3 to 5 times faster per drop. 

The speed and efficiency of FWD and FastFWD testing enables the collection of comprehensive and up-to-date pavement performance data within strict time constraints, despite the extensive road networks requiring assessment. 

How FWD Testing Works

FWD equipment applies a known load to the pavement surface. Sensors record the pavement’s deflection basin, which represents how the structure responds under stress. This data, in conjunction with as-built information or geotechnical investigation, can be analyse to determine the estimated pavement layer stiffness.

FWD testing has been used extensively across the Canadian Prairies and internationally for several decades. The analysis and interpretation of FWD data are supported by well‑documented and established guidelines, developed through substantial body of historical FWD data and review of pavement performances after rehabilitation treatments informed by FWD results. The Transportation Association of Canada provides guidance on pavement structural evaluation and rehabilitation planning, which aligns with how municipalities use FWD data.

FWD data provides objective and representative of real traffic loading conditions.

Why FWD Testing Helps Prairie Communities Optimize Budgets

1. Supports Cost‑Effective Treatment Selection

Structural testing helps engineers determine whether a roadway requires reconstruction, resurfacing or strengthening. This reduces the risk of over‑designing projects and ensures rehabilitation dollars are used effectively.

2. Extends Roadway Life

FWD data identifies early structural weakness, which allows municipalities to schedule preventive maintenance. These interventions are often more economical than major rehabilitation later in the pavement lifecycle.

3. Helps Prioritize Projects Fairly and Objectively

For the Prairie communities, transparent decision‑making is essential. FWD results provide a factual basis for prioritizing rehabilitation work and supporting recommendations presented to councils or committees.

4. Improves Long‑Term Capital Planning

When structural data is built into pavement management programs, municipalities can better forecast when roads may need attention. This supports predictable budgeting and long‑term financial planning.

How ParklandGEO Supports Road Rehabilitation Planning

Since 2000, ParklandGEO has worked with municipalities across Western Canada on pavement rehabilitation, but the value in our multidisciplinary approach is in how we apply that in practice.

Most roadways aren’t failing uniformly.  Subgrade soils are inherently variable, and that variability governs structural response, resulting in localized differences in stiffness and load distribution. You’ll see sections that are structurally sound right beside areas that are clearly overstressed or moisture-compromised. Treating those the same is an expensive mistake to make.

 

ParklandGEO’s approach is to break that down systematically:

·       What is each section of the pavement doing structurally?

·       Is the issues surface-related, or is it coming from the base or subgrade?

·       Are pavement distresses driven by loading, drainage, material quality or any combination of these factors?

To do this, we integrate FWD data, subsurface soil conditions, and material performance to answer these questions. This allows us to move away from blanket overlays and toward targeted rehabilitation strategies that address the root causes of roadway performance issues.  This will allow for better capital planning, and avoiding common issues with rehabilitation projects, whether overdesign and unnecessary cost or under designing and seeing reoccurring failures.

ParklandGEO Timely Data Delivery for Effective Road Rehabilitation 

Historically, we’ve done a lot of FWD analysis and interpretation. The gap was always coordination and logistics: different groups handling collection, processing, and design inputs.

With the addition of the Dynatest Model 8012 FastFWD, we now control that full workflow:

 

·       Field data collection 

·       Data QA/QC and interpretation 

·       Integration into rehabilitation recommendations 

By keeping the process internal, we’re working off the same dataset, the same assumptions, and the same accountability from start to finish.

The other practical advantage is speed. FastFWD lets us cover significantly more roadways in a given window, which becomes critical when you’re working around traffic, weather, or tight construction schedules. Dynatest estimates that the FastFWD unit is approximately five times compared to conventional FWD.

A good example is the Southeast Stoney Trail Overlay Project. This is a major corridor, with multiple stakeholders involved:

·       ~25 km of six-lane highway 

·       Multiple interchanges and structures 

·       Additional work along Deerfoot Trail

By the time we were brought in, construction planning for 2025 was already underway.  Our scope of work wasn’t to redefine the rehabilitation strategy, it was to provide current field data so that the design team could confirm that the proposed design aligned with actual in-situ pavement and subgrade conditions. Could we be confident that the design assumptions still match the actual soil conditions?

We completed FWD testing across ~125 lane-km in just three-night shifts, using traffic control vehicles and a moving lane closure that allowed traffic to safely flow around the operation. No full lane closures and no extended disruptions, and with limited nightly window, we focused on efficient data collection. For comparison, a conventional approach would have required 8 or more shifts to complete the same coverage.

After processing and analysing the data, there was no need redesign.  Instead, the work confirmed, using real world data, of where the structure was performing as expected and where it wasn’t.  This allowed the team to:

·       Avoid defaulting to conservative (i.e. thicker) overlays across the entire corridor

·       Apply targeted, localized improvements to sections where they were actually needed

·       Move forward with the project with confidence, instead of relying on contingencies

At a high level, it’s easy for any consultant to say that they will “support decision making”. The goal at ParklandGEO is add value in other ways:

·       Identifying structural issues from surface distresses

·       Quantifying the inherent variability of a pavement structure throughout its alignment

·       Providing recommendation that is tied to actual performance rather than assumptions

·       Doing so in a timely manner

ParklandGEO’s services that support pavement planning include:

 

·       Materials testing, which helps verify asphalt, soil and aggregate properties during construction and rehabilitation. These tests provide insight into strength, durability and suitability, allowing project teams to confirm that materials meet engineering expectations. 

·       Geotechnical engineering, which provides insight into subsurface conditions and soil behaviour. Understanding soil strength, moisture conditions and layer characteristics helps inform pavement design, rehabilitation strategies and long-term performance planning.

With these services available under one organization, municipalities benefit from consistent reporting, coordinated data interpretation and reliable project support from planning through construction.

Why FWD Testing Matters in the Prairies

The Prairies face conditions such as expansive clay soils, freeze‑thaw cycles and heavy truck traffic. These factors influence pavement strength and long‑term performance. FWD testing helps municipalities:

·       reduce unexpected pavement failures

·       target spending where it has the most value

·       plan treatments that match local soil and traffic conditions

·       maintain safer and more reliable road networks

FAQs About Road Rehabilitation and FWD Testing

What is FWD testing used for in road rehabilitation?

FWD testing measures pavement structural capacity, helping determine whether roads require maintenance, resurfacing or reconstruction.

How does FWD testing help reduce maintenance costs?

By identifying structural weakness early, FWD testing supports timely preventive treatments, which are typically less costly than major rehabilitation. 

Why is FWD testing important for Prairie road networks?

The Prairies roads experience unique soil and load conditions. FWD testing provides accurate data that helps municipalities plan appropriate and cost‑effective rehabilitation strategies.

Plan Smarter with ParklandGEO

Effective road rehabilitation begins with accurate pavement insights. ParklandGEO offers regionally informed analysis and practical recommendations to support responsible planning across Prairie communities. Contact ParklandGEO to discuss your upcoming road rehabilitation project.