This paper documents the construction and settlement monitoring of an 18 m high roadway embankment that was constructed over two gravel quarry wash ponds for James Walker Trail located in Cochrane, Alberta.
The primary objective of the work was to ensure that embankment settlement would not adversely affect the performance of the future roadway/pavement structure. In addition, the project focused on reducing the amount of imported backfill and reusing available on-site soils.
The key challenge of the project was determining how to reuse the existing wash pond sediment to safely construct the embankment without adversely impacting the future roadway performance. The existing pond sediment consisted of wet, fully saturated, soft, sandy silt, varying between 2 m and 5 m thick with an estimated volume of up to 50,000 m3.
The optimized simple design approach and proposed construction plan consisted of using a combination of geotextiles for soil stabilization and installing a drainage blanket connected to multiple drain outlets to drain the excess porewater out of the pond sediments during and after construction. The existing wash pond sediment material was able to be left in place and was reused as part of the embankment structure, thereby reducing the need to remove the pond sediment and import new fill.
The roadway embankment fill was subsequently placed in a staged approach to allow construction to continue safely while monitoring porewater pressure and settlement using a series of vibrating wire piezometers, vibrating wire settlement gauges, and settlement monuments. The embankment fills also reused reclaimed cobbles/boulders and on-site available soils including clay, silt, and sand to reduce the amount of import fill required.
The project was successful in reusing the estimated 40,000 m3 of pond sediment, reusing available on-site soils, and minimizing the amount of import fill required. In addition to the cost savings related to these activities, several environmental benefits were also indirectly realized. Energy use and carbon emissions decreased due to reduced construction equipment operation and hauling activities associated with the pond sediments (i.e., up to 80,000 m3 for the exporting of pond sediments and importing of new fill). Reusing on-site soil materials also reduced the environmental footprint of the project by minimizing the need to extract more fill from other sites, disposal of pond sediments, and reduced hauling activities along with any associated traffic congestion.
Ultrasonic pulse velocity (UPV) is a popular non-destructive testing (NDT) technique for the rapid assessment of materials and infrastructure conditions without causing any damage. UPV is less time-consuming and labour-intensive than conventional inspection techniques commonly applied to the field- and lab-produced asphalt concrete specimens. In this study, different asphalt mix specimens were produced with 50% Reclaimed Asphalt Pavement (RAP) and four bio-based rejuvenators. A control mix with 20% RAP was also prepared with a verified Job Mix Formula (JMF). During the volumetric mix design, the ease of compaction was observed on rejuvenated high RAP mixes in terms of the reduced number of gyrations compared to the control mix. However, the compaction temperature and conditioning time of the high RAP mix was kept the same as the control mix. The volumetric requirements as per Ontario Provincial Standard Specification (OPSS) 1151 were met for the mixes. This paper attempted to use UPV measurements on the rejuvenated high RAP mix and control mix specimens to examine the condition of these mixes, especially those with reduced compaction effort. Different wave characteristics, including group P-wave velocity and peak-to-peak (PTP) amplitude of the first arrival P-wave in the time domain signal, and spectral area, peak spectral magnitudes, peak frequencies in the Fourier spectra, were evaluated to compare the different mixes. After performing UPV tests, the Hamburg Wheel-Track Testing (HWTT) was performed on the same specimens. The results provided a rapid evaluation of the high RAP mixes at high frequency (low temperature) and high temperature (low loading frequency) domains.
Research and implementation of Performance Engineered Pavements (PEP) have been gaining momentum, especially during the past two decades. Several factors including but not limited to the sample preparation methods, specimen dimensions, compaction level, performance testing method, variability of results, minimum and maximum thresholds, and sensitivity to materials sources can be named among other major contributors in this area. This paper provides a summary of major procedures and protocols used by national and international transportation agencies toward performance testing. Furthermore, this paper presents a synthesis of the critical steps that should be considered by highway agencies in utilizing performance testing into design, performance verification, and/or quality assurance part of contracts. Successful implementation of this approach requires understanding the rationale behind development of the commonly used methods. Therefore, this paper also provides relevant aspects of the research work behind development of most specified test methods, and how several factors could influence the accuracy and variability of the test results. To this end, factors such as: air voids, thickness variation, cutting and coring methods, and compaction using gyratory or slab compactors, are considered and discussed in this paper.
The load carrying capacities, relative strengths and the required overlays of existing pavements are generally determined using the measured surface deflection values. The Falling Weight Deflectometer (FWD) is the most common device for measuring pavement surface deflections. In all general pavement design and analysis, the measured deflection values are corrected to a standard effective pavement temperature. However, the effective pavement temperatures have been typically measured using an oil, poured into the predrilled holes on pavement surface. Such temperatures may not truly reflect the temperatures of pavement layers or materials. In addition, highway agencies typically apply a correction factor to central deflection only or apply a single temperature correction factor to all geophone deflections at a test point. These could result in some errors because of not accounting for the effect of temperature or lower sensitivity of farther (from FWD plate) geophone deflections to changes in temperature. Some jurisdictions, like Manitoba, also adopted the Benkelman Beam Rebound (BBR) deflections temperature correction models for FWD deflections. This may not be appropriate because of two different mechanisms of deflection measurement.
Manitoba Transportation and Infrastructure (MTI) has collected the temperature data from several thermistors to develop a new model for estimating the effective pavement temperature. The measured FWD deflections and temperatures at different sites were then used to develop a separate temperature correction model for each geophone deflection. The results and analyses showed that the estimated pavement effective temperatures using the new interim model are higher, with a smaller difference between the surface and effective temperatures, than that estimated using the currently used model. The correction model is different for each geophone deflection with a progressively smaller regression coefficient for geophones away (up to 900mm) from the centre of the FWD load plate. The new interim models also provide a reduction in the required overlay thickness.
Asphalt binder aging is recognized as a complex phenomenon that can significantly reduce the serviceability of flexible pavements. To address this issue, the aging behaviour and rheological properties of asphalt binders can be improved through asphalt binder modification. In this regard, the use of nanotechnology and nanomaterials are among the promising approaches for this purpose. The main objective of in this paper is to investigate the use of two types of Organo-Montmorillonite nanoclays with different dosages (2% and 4% by weight of asphalt binder) for enhancing the aging resistance of asphalt binders. Nanoclay-modified asphalt binders are prepared using a high shear mixer at 130±2 °C for 2 h at 3,000 rotations per minute. Initially, for the purpose of evaluating the material properties, various tests are applied to the unmodified and nanoclay-modified binders. The performance grades of the unmodified and modified binders are also investigated. Moreover, by examining the evolution of the fractions (i.e., saturates, asphaltenes, resins, and aromatics) the colloidal index is calculated and the storage-stability of the nanoclay-modified binders is analyzed accordingly. The asphalt binders modified with 4% nanoclays are found to have the best storage-stability among the evaluated binders. After characterizing the unaged properties, rolling thin-film oven (RTFO) aging was carried out for 85 minutes at 163 °C, followed by aging in pressure aging vessel (PAV) for 20 h under 2.1 MPa pressure at 100 °C. Using a dynamic shear rheometer, the complex shear modulus (G*) and phase angles (d) of the binders were determined at different temperatures and loading frequencies before and after aging. Finally, based on the aging indices, the impact of nanoclay modification on the aging resistance of asphalt binders was investigated. The results of this study showed that nanoclay modification can mitigate the impact of aging on asphalt binders compared to the unmodified binder.
Lightweight Cellular Concrete (LCC) is gaining popularity for its use in various construction projects. The feasibility of incorporating LCC into pavement construction has recently been investigated. This study analysed construction activities' effects on three LCC densities and granular A material to examine further the viability of employing LCC as a subbase alternative to unbound aggregate. This included designing, instrumentation, and building a four-section 200-meter field segment. A control section employed granular A as a subbase layer, while LCC400, LCC475, and LCC600 sections applied 400 kg/m³, 475 kg/m³, and 600 kg/m³ LCC as subbase, respectively. The density of LCC were chosen based on past industry experience for pavement construction. Materials applied in the other layers were the same in all four sections. Subsurface instrumentation was installed to monitor the pavement pressure, strain, moisture, and temperature response. The predicted ultimate strengths for 400, 475 and 600 kg/m³ were found to be 0.93 MPa, 1.93 MPa, and 2.08 MPa. Results also indicated that the control section experienced 78% more peak pressure than the LCC475 and LCC600 sections and 61% more pressure than the LCC400 section during construction. It was determined that a long-time frame between LCC pour and asphalt paving operation coupled with excessive truck traffic before asphalt paving could be detrimental to the performance of LCC pavements. This is due to high strain responses and damage to the LCC homogenous air bubble structure.
In many areas of Western Canada, infrastructure construction occurs in areas of undesirable native materials. Concerns such as yielding or friable soils, differential consolidation, subsurface wetland charging, intense freeze thaw cycles, and variable subsurface water levels create substantial challenges for construction. Undeniable changes in the climate are also creating concerns that affect the performance of transportation assets which should be addressed as part of a full life cycle analysis. As an example, in northern Alberta regular freeze thaw cycles are a normal and anticipated condition. These concerns are typically accounted for in design, material selection and construction practices. However, in recent years there have been instances where the full design life is not being achieved which may partially be attributed to previously unpredicted changes to the climate.
This paper and presentation will discuss advancements in the areas of design, material management, product selection and construction practices which are intended to effectively meet these needs. Topics will include parameters such as analysis of phreatic surfaces, circular failures and finite elements. Discussion will include construction material considerations including the use of different soil types for various applications and the use of engineered products such as structural geogrids and geotextiles which may be used to separate materials and increase overall material strengths. In addition, these concepts will be tied into the Climate Change theme by suggesting ways to mitigate these concerns. A case study will be reviewed; the grading and paving work completed on Range Road 183 in Yellowhead County which included construction over significant lengths of deep muskeg with several drainage and pipeline crossing concerns. This type of terrain, once avoided at all costs, often caused significant route selection concerns. However, with proper consideration and analysis of the soils and materials, use of advanced products and proven, effective construction methods, roads and other infrastructure assets may now be successfully built within areas that were previously not considered suitable.
The South Fraser Perimeter Road (SFPR) is an approximately 40 kilometer long, four-lane roadway located in the Greater Vancouver Area of British Columbia. The route extends along the south side of the Fraser River from Deltaport Way in Delta to 176th Street (Highway 15) in Surrey. The SFPR provides an efficient and convenient transportation corridor, with connections to major trade gateways for commercial transportation of goods from Delta and Surrey ports and ferry terminals, as well as for tourists and commuters.
The roadway was procured by the BC Ministry of Transportation and Infrastructure as a P3 using a Design Build Finance and Operate (DBFO) model. It was fully opened to traffic in December 2013 with the design/build phase being completed 6 months ahead of schedule by the Concessionaire, Fraser Transportation Group Partnership (FTG). The road is now in the 9th year of the 20-year operation and maintenance phase.
Applying remediation efforts to improve driver comfort can be challenging in different areas of the SFPR which have site-specific challenges exacerbated by differential settlement issues. Through several examples, this paper discusses some of the challenges experienced through the design and implementation of the various site-specific remediation efforts to improve driver comfort and operational safety.
Currently, pavement condition analysis used by Ontario municipalities utilize at least six different pavement evaluation strategies, namely, Inventory Manual Methodology (IMM), Overall Condition Index (OCI), Pavement Condition Index (PCI), Pavement Quality Index (PQI), Structural Adequacy Index (SAI), and Surface Condition Index (SCI). Also, many municipalities and consultants use modified versions of existing evaluation methodologies (adding/removing distress types or weighting criteria) to suit their individual needs. Ontario Regulation 588/17: Asset Management Planning for Municipal Infrastructure mandated the concept of levels of services for all asset classes. For paved roads, municipalities are required to report an average PCI value; however, the Ministry of Infrastructure used this terminology to refer to any numeric evaluation strategy.
This paper explores the need to standardize pavement condition evaluation methodology used by infrastructure owners across Ontario. This paper focuses on a review of the pavement condition evaluation methodologies being used by Ontario’s municipalities, quantifying the differences, and consolidating recommendations towards pavement condition evaluation standardization. A literature review was conducted to understand the pros and cons of variability in pavement condition evaluation methods. The paper presents results from survey of infrastructure agencies in Ontario which presents trends and variabilities in pavement condition evaluation methodologies. A field pavement condition investigation was performed on four sections of municipal roads in Ontario to understand the effect of different methodologies on the outcome pavement evaluation.
The New Brunswick Department of Transportation and Infrastructure (NBDTI) highway network contains over 2100 large culverts with over 75% of this inventory expected to require renewal within the next 20 years. Over half of the inventory requiring renewal are corrugated steel pipes (CSPs), which have shown to have the shortest service life of all culvert types installed since the 1960s. Conventional cut-and-cover culvert replacements, especially in deep fill embankments, are costly and disruptive to traffic and the environment. It was determined that trenchless methods should be considered for these culverts where conditions are suitable. In January of 2021, a New Brunswick contractor proposed the trenchless method of lining existing culverts with a spray-applied geopolymer material (Geospray) supplied by GeoTree Solutions. Subsequently, NBDTI engaged in a field trial of geopolymer mortar. The main objective of the trial is to determine the suitability of this rehabilitation method for ongoing implementation in NBDTI culverts.
The asphalt binder is a viscoelastic substance that exhibits both viscous and elastic behaviour. Asphalt binder is an effective adhesive material for use in the pavement, however it is a difficult material to understand and describe due to the wide variety of its behaviour. This research aimed to investigate the impact of polymer modification on nonrecoverable creep compliance (Jnr). Three modifiers (fly ash (FA), Styrene-Butadiene- Styrene (SBS), and fly ash-based on geopolymer (GF)) were used. Asphalt binders were tested at various temperatures, ranging from 40 to 70 °C with a 3 °C gap, and regression models were developed. The results revealed that 2% SBS modified asphalt binder exhibited elastomeric behaviour at low temperatures, whereas 4% SBS modified asphalt binder exhibited noteworthy elastomeric behaviour at various temperatures. The power-law models most effectively illustrated the correlation between temperature and nonrecoverable creep compliance (Jnr) at different stresses, 0.1 kPa and 3.2 kPa. The developed models proved to be effective for appropriately selecting the polymer type and amount suitable to minimize the Jnr. The hybrid and 4%SBS binders performed best in terms of strain recovery at high temperatures, with Jnr values of less than 0.5 being achieved at 58 °C and 3.2 kPa.
The asphalt binder is a viscoelastic substance that exhibits both viscous and elastic behaviour. Asphalt binder is an effective adhesive material for use in the pavement, however it is a difficult material to understand and describe due to the wide variety of its behaviour. This research aimed to investigate the impact of polymer modification on nonrecoverable creep compliance (Jnr). Three modifiers (fly ash (FA), Styrene-Butadiene- Styrene (SBS), and fly ash-based on geopolymer (GF)) were used. Asphalt binders were tested at various temperatures, ranging from 40 to 70 °C with a 3 °C gap, and regression models were developed. The results revealed that 2% SBS modified asphalt binder exhibited elastomeric behaviour at low temperatures, whereas 4% SBS modified asphalt binder exhibited noteworthy elastomeric behaviour at various temperatures. The power-law models most effectively illustrated the correlation between temperature and nonrecoverable creep compliance (Jnr) at different stresses, 0.1 kPa and 3.2 kPa. The developed models proved to be effective for appropriately selecting the polymer type and amount suitable to minimize the Jnr. The hybrid and 4%SBS binders performed best in terms of strain recovery at high temperatures, with Jnr values of less than 0.5 being achieved at 58 °C and 3.2 kPa.
Calgary’s road network constitutes a major investment over many generations and plays a crucial role in the City’s well-being by guaranteeing its citizens with full accessibility, ensuring safe travel, and providing a strong business competitiveness through an efficient movement of goods and services. This study identifies key limitations in current pavement network life cycle cost analysis processes by comparing the results of traditional prioritization approaches to a true multi-year multi-constraint optimization analysis. The results shows that the optimization solutions outperformed prioritization at all years showing an average 5.3% improvement over the planning horizon and 9.3% by the end of the plan. Monetization methods also arrived at significant cost savings via added performance over a 10-year planning horizon by switching to a mathematically optimized solution. To further improve modeling accuracy and reliability of results, this study investigates the quality of performance models used within the pavement management system and discusses the development of machine learning-based deterioration models using decision tree regression. The effects of more modern performance modeling methods on investment planning is examined by comparing various optimization scenarios using both the ML-based and the traditional age-based deterioration models. The paper shows the importance of condition-based predictive modeling and integrating accurate performance models into the current asset management system to provide more accurate information on monitoring the network's life expectations, capital investment plans, and vulnerable communities with accelerated pavement deterioration patterns.
COVID-19 imposed travel restrictions have induced significant changes to our travel behaviour and daily life, such as work-from-home and online learning. The long-lasting nature of this pandemic might trigger a longer-term change in our behaviour after the pandemic, such as continued preference for work-from-home and e-learning. Such changes in work and learning arrangements do not only indicate a reduction in travel during the peak hour, it might also indicate a shift in travel to other times of day as well as changes in trip purposes and travel distances. For example, a worker telecommuting might spend the whole/part of the day at home and then go out to meet friends/family for dinner and do groceries from a store near the home while returning. Traditional four-stage travel demand models typically take the origin-destination (O\D) matrix for the peak hours as input at an aggregate-level of temporal, spatial, and population resolution and do not necessarily accommodate the trip chaining behaviour of an individual. As a result, the behavioural changes associated with time-sensitive policies such as work-from-home and e-learning are not accommodated and/or reflected by these models. This demands the development agent-based transport simulation models adopting activity-based modelling technique. This study adopts an agent-based transport network simulation technique to generate 24-hour traffic for alternative work-from-home and online learning strategies. The model is calibrated and validated for the Central Okanagan region of British Columbia, Canada. Specifically, the open source Multi-Agent Transport Simulation (MATSim) model has been adopted, which was written using the Java programming language. The 24-hour travel schedule is developed adopting an activity-based modelling technique. The findings of this study will assist the governments and transit agencies in understanding the dynamics of travel behaviour and the consequent change in traffic patterns over the 24-hour for alternative work arrangement scenarios.
The advancement of new laser technologies in recent years has changed the resolution of pavement data captured during collection, creating the opportunity for a fully automated approach to condition evaluation. Inspired by the Universal Cracking Indicator proposed by William Paterson in 1994, and developed by the ASTM E17 working group, this paper will present the application of the Pavement Surface Cracking Metric (PSCM). By using quantitative definitions in order to ensure consistency of the results, this method removes the subjectivity that happens with human rating of pavement distresses. The repeatability and reproducibility of the method were assessed by collecting multiple runs of pavement data on three separate asphalt sections. The application of the Pavement Surface Cracking Index (PSCI) to convert the PSCM value, which is a physical property of the pavement, into a 100-0 score of the pavement section is also presented. Finally, the use of the PSCM to classify the pavement distress and the inclusion of potholes and patching in the metrics are also discussed.
The City of Calgary (The City) initiated one of the first Warm Mix Asphalt (WMA) technology projects in Canada in 2005 with Tetra Tech Canada Inc. A follow-up assessment of that project was completed in 2021. This paper discusses the evaluation of the 2005 project data and the outcomes of the follow-up investigation. The Demonstration Project to evaluate WMA was constructed in Calgary in 2005. The project compared three surfacing mix types: a control mix and two WMA alternatives. The project successfully implemented the new technology. The 2021 assessment had the objective of reviewing details from the original project, completing a field assessment of the current conditions, and implementing a suitable laboratory program to assist The City in determining the feasibility of future use of WMA technology. The 2021 assessment studied the relative strength of the WMA layers and binder properties to determine the difference between Hot Mix Asphalt (HMA) and WMA. An industry assumption is that WMA is prone to reduced stiffness given the reduced mixing temperatures; however, the outcome of this trial project opposed this assumption and the results indicate that these WMA technologies could be considered equivalent to HMA in terms of design and performance.
Tetra Tech Canada Inc. was retained by Alberta Transportation (AT) to assist in the development of a risk-based Geotechnical Asset Management (GAM) framework and pilot study, with the vision of transforming AT’s current Geohazard Risk Management Program (GRMP) into a GAM program. The main objectives of the study were to develop a GAM framework for managing selected geotechnical assets located along the Provincial highway system, and to develop a spreadsheet tool for implementing this framework to a pilot-scale inventory of 27 geotechnical assets. The intent of the GAM framework development was to enhance AT’s ability to effectively prioritize, measure, and manage life-cycle investments in assets such as slopes, embankments, retaining walls and subgrades, based on performance expectations and risk tolerance. The GAM Framework Development and Pilot Study was undertaken in a manner consistent with the methodology and recommendations of NCHRP Report 903: Geotechnical Asset Management for Transportation Agencies (2019), which includes a supporting computational tool implemented in Microsoft Excel, that was customized as part of the project. The tool includes economic analyses based on annual monetized risk and life-cycle costs over a 50-year time period, through monetizing the asset-specific costs and benefits associated with the recommended treatment, applied in the optimal year. A collaborative and highly-interactive approach was essential to the project delivery, with AT’s Geotechnical Asset Management Specialist involved as one of the key team members during all stages of the project. The customized “GAM Planner” application provides an integrated solution for collecting, storing, and managing information on Alberta’s geotechnical highways assets, in one Excel-based application which can be used for capital planning and the prioritization of rehabilitation projects on an annual basis. The GAM Planner was modified from the original NCHRP tool, to reflect AT's agency-specific requirements regarding inventory, treatments, inspection requirements, site-specific user cost model, risk-based life cycle plan, incorporation of monetized risk, site-specific traffic, site-specific detour length, provincial highway classification, field inspection report, and other additional enhancements.
This paper describes the methodology used to conduct the Study on the Infrastructure Vulnerability and Risk due to a Changing Climate and Extreme Weather Events along the Alaska Highway. The Study was carried out using the methodology documented under the Vulnerability Assessment and Adaptation Framework (FHWA, 2017). The Framework provides a structured process for conducting a vulnerability assessment for the infrastructure assets. The Study assessed the impacts of climate change on drainage and geotechnical assets. It provided a specific analysis of projected changes in temperature and precipitation-related parameters as predicted by climate change models to establish a probable range of future climate conditions to which these assets may be subjected. A Life-Cycle Cost Analysis (LCCA) was carried out to identify and select the most cost-effective adaptation alternatives. This economic analysis monetized the costs and benefits associated with multiple adaptation strategies over a 60-year analysis period. The costs considered in the LCCA include both "direct costs," the cost directly incurred by the asset owners, and "user costs," costs that users of the road would incur through delays and detours. A total of 410 culverts, 74 geotechnical assets and 24 bridges along the highway were identified for consideration in this Study. The methodology is intrinsically compatible for integration into Transportation Asset Management Plans and cross-asset optimization.
Anthropogenic climate change is among the greatest challenges we face, given the threat it poses to the natural and built environments. This paper addresses resilience of pavements in the context of climate change by reviewing the major vulnerabilities and adaptation measures. First, the basic concepts relevant to this topic, such as sources of climate information and downscaling climate data, climate scenarios, and uncertainty in climate projection, are introduced. The climate-induced pavement stressors of particular interest in this regard are increases in temperature and precipitation intensity. As such, the proposed engineering-informed adaptation measures relevant to these stressors are evidence-based, and they relate to monitoring pavement key performance parameters and pavement adaptations in structural design, materials, and mix design, along with adaptation in maintenance, regulations, and construction. The measures proposed in various research studies include increasing pavement layer thickness, using stiffer binders, use of geotextiles, performing more frequent maintenance, and enforcing more stringent acceptance tolerances for mixes and materials. This study concludes that climate adaptation measures in pavement should be incorporated in the decision-making process at the planning and design stages. In turn, this underscores the importance of integrating practical adaptation strategies in design and construction standards and supporting awareness of, and education on, climate change adaptation among engineers and practitioners.
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