Pavement Life Cycle Assessment Research Articles

A holistic life cycle assessment of steel bridge deck pavement

Transportation serves as a cornerstone of economic development and is a significant contributor to carbon emissions. This study established a life cycle assessment model that incorporates refined carbon emission calculation parameters, streamlining the computation process while maintaining precision. A case study was conducted to quantify the life-cycle CO2 emissions of steel bridge deck pavements, a pivotal component within the transport network. The study suggests using the average annual CO2 emissions as a metric to gauge the carbon emission potential of steel bridge deck pavements with different service lives. This study addresses a void in the existing work by standardizing the grading of typical pavement diseases and quantifying the carbon emissions of the corresponding maintenance measures. It reveals that the pivotal determinant of life-cycle CO2 emissions for steel bridge deck pavements is the service performance of the paving material. Comparative analysis indicates that epoxy asphalt concrete could be deemed a low-carbon material, achieving a 77.6% reduction in life-cycle carbon emissions compared to gussasphalt concrete. Emissions during the maintenance phase constitute 66.7%–71.4% of the total life-cycle emissions, predominantly due to end-of-life and traffic delay units. The methodology and calculated data presented herein can inform subsequent carbon reduction strategies in transportation and promote the development of resilient infrastructure, thus making a substantial contribution towards carbon neutrality and climate change mitigation.

Mechanistic-empirical pavement design to include mechanical performance of rubberized asphalt pavements in the use stage of life cycle assessment

The use phase of road pavements includes fuel consumption, urban heat island, and leaching. Life cycle assessment (LCA) often omits the use phase for its complexity. The use phase should also consider the durability of the asphalt mixtures. This study used the Mechanistic-Empirical Pavement Design to include the durability of five asphalt mixtures (control, styrene-butadiene-styrene - SBS, polymer coated rubber - PCR dry and wet, and devulcanized rubber - DVR) in the LCA of 1-mile road pavement over 50 years. Considering only the impact of the mixture production, the control mix had a carbon footprint 12.9 % lower than the other mixtures. When including the durability, the control mixture's carbon footprint was 69 % and 84 % higher than SBS and PCR dry mix, respectively. This study showed the importance of including the mechanical performance of the asphalt mixtures to better evaluate the environmental impact of road pavements over the service life.

A Review on Life Cycle Assessment of Pavements in Brazil: Evaluating Environmental Impacts and Pavement Performance Integrating the International Roughness Index

This article addresses the limited understanding of the landscape regarding Life Cycle Assessment (LCA) in Brazilian pavement infrastructure. It provides an overview of LCA’s application in assessing the environmental effects of pavements while exploring the use of the International Roughness Index (IRI) as a performance criterion to assess environmental consequences and pavement performance. A comprehensive search for relevant quantitative LCA studies, published from 2013 to 2023, was conducted across several bibliographic databases, following ISO 14040 standards. A total of fourteen case studies were analyzed, providing insight into frequently used software, databases, Life Cycle Impact Assessment (LCIA) methods, and functional units. Furthermore, global warming or greenhouse gases (GHG) were the most frequently used environmental indicators, while materials, transportation, and construction were the most inventoried life cycle phases. However, the search also highlighted limitations, including the availability of Brazilian data and scope definition. Nevertheless, a quantitative comparison between conventional pavements showed a low standard deviation. The scenarios studied demonstrated that using recycled materials in pavement construction and employing high-strength materials in layers and subgrade can reduce environmental impacts. In conclusion, these findings contribute to the development of sustainable pavement practices in Brazil and highlight the need for further research to validate current findings and address existing gaps.

Environmental life cycle assessment of bridge deck pavement and case studies of two bridges in China

The durability of deck pavement material has great impact on deck performance and carbon emission. This paper aims to analyze the durability of different deck pavement materials and structures by taking two bridges across the Yangtze River in China as examples, and establish the carbon emission model of the bridge deck pavement during the whole life cycle. The carbon emissions of the two bridges during twenty years of service are then calculated based on the model. It can provide reference for future bridge deck pavement schemes and measures to reduce carbon emissions. In this paper, two typical representative bridges in Jiangsu Province in East China are selected for case analysis, namely the Jiangyin Yangtze River Highway Bridge and the Second Nanjing Yangtze River Bridge. Firstly, this paper introduces the specific forms of various bridge deck pavement schemes since the construction of the two bridges. After many years of experiments, the pavement of the Jiangyin Yangtze River Highway Bridge has changed from mastic asphalt mixture to double-layer hot mix epoxy asphalt concrete, and that of the Second Nanjing Yangtze River Bridge has changed from warm mix epoxy asphalt to hot mix epoxy asphalt. Focusing on the carbon emission of bridge deck pavement, the carbon emission model of different asphalt mixture pavements based on life cycle assessment (LCA) is established. The assessment can be divided into five stages: material production, transportation, construction, maintenance and demolishment. This paper takes extra traffic congestion during repair and maintenance into consideration. In this paper, two bridges were taken as cases to calculate the carbon emission. In initial construction, the deck of the Jiangyin Yangtze River Highway Bridge was paved with mastic asphalt mixture; while the deck of the Second Nanjing Yangtze River Bridge was paved with epoxy asphalt concrete. The paving material of the Jiangyin Yangtze River Highway Bridge was changed into epoxy asphalt concrete gradually in repair and maintenance. The analysis results show that in the initial 20 years of life, considering the initial construction and major maintenance of deck pavement, the total carbon emission of the Jiangyin Yangtze River Highway Bridge and the Second Nanjing Yangtze River Bridge is 179,195 kg CO2e and 101,577 kg CO2e respectively. The unit carbon emission of the Jiangyin Yangtze River Highway Bridge after 20 years of opening to traffic is 5.079 kg/m2 CO2e. The proportions of the five stages were 76.4 %, 2.7 %, 2.5 %, 16.8 % and 1.6 %, respectively. The unit carbon emission of the Second Nanjing Yangtze River Bridge after 20 years of opening to traffic is 3.352 kg/m2 CO2e. The proportions of the five stages were 66.3 %, 2.4 %, 2.6 %, 28.2 % and 0.6 %, respectively. The results show that epoxy asphalt material has better durability and can reduce carbon emission of bridge deck pavement.

Uncertainty analysis of life cycle assessment of asphalt surfacings

The Life Cycle Assessment (LCA) of asphalt pavements are associated with significant uncertainty resulting from variability in the quantity and impact of individual components, the quality of data for each component, and variability of asphalt durability. This study presents a framework to quantify and incorporate the uncertainty of LCA and asphalt durability data into LCA of asphalt surfacings. The suggested framework includes: estimating the uncertainty of asphalt production processes by the pedigree matrix method, conducting a deterministic LCA, applying Monte Carlo Simulation (MCS) to estimate the probability density functions (PDFs) of the considered impacts using the uncertainty data, deterministic solution, and asphalt durability. This framework was applied to six asphalt mixtures; the results show that there is significant uncertainty in the processes that contribute to the environmental impacts. They also showed that considering asphalt durability and its uncertainty is critical and can significantly change the results and interpretation of LCA.

Life cycle assessment of lightweight cellular concrete subbase pavements in Canada

ABSTRACT The use of Lightweight Cellular Concrete (LCC) as a subbase alternative to typical flexible pavement subbase material in cold regions is gaining attention. Since a setback of using LCC is its high cement content, which is a significant source of carbon dioxide (CO2) emissions, it becomes imperative to consider this aspect when proposing LCC for pavement applications. This study evaluated the environmental impact of three densities (400, 475, and 600 kg/m³) of LCC produced with two methods (wet and dry mix) and compared to two types of unbound granular material (granular A and B) as flexible pavement subbase. The pavement performance was predicted using MEPDG and WESLEA software and compared with measured field responses as a basis for maintenance strategy. The Life Cycle Assessment (LCA) results showed that lower-density LCC pavements decreased environmental costs by reducing total life CO2 emissions by up to 16% and reducing environmental impact for Carbon monoxide, Sulphur dioxide, Nitrogen oxide, Particulate Matter (PM)2.5, PM10 and total PM compared to granular A and B pavements. As LCC density increased, more emissions occurred, showing the importance of density to emissions output. This research demonstrates the potential benefits of using LCC as an alternative subbase pavement material.

Environmentally-extended input-output analyses efficiently sketch large-scale environmental transition plans: Illustration by Canada's road industry

Industries struggle to build robust environmental transition plans as they lack the tools to quantify their ecological responsibility over their value chain. Companies mostly turn to sole greenhouse gas (GHG) emissions reporting or time-intensive Life Cycle Assessment (LCA), while Environmentally-Extended Input-Output (EEIO) analysis is more efficient on a wider scale. We illustrate EEIO analysis' usefulness to sketch transition plans on the example of Canada's road industry: estimation of national environmental contributions, most important environmental issues, main potential transition levers of the sector, and metrics prioritization for green purchase plans. To do so, openIO-Canada, a new Canadian EEIO database, coupled with IMPACT World+ v1.30–1.48 characterization method, provides a multicriteria environmental diagnosis of Canada's economy. The construction sector carries the second-highest environmental impacts of Canada (8–31% depending on the indicator) after the manufacturing industry (20–54%). The road industry generates a limited impact (0.5–1.8%), and emits 1.0% of Canadians' GHGs, mainly due to asphalt mix materials (28%), bridges and engineering structures materials (24%), and direct emissions (17%). The industry must reduce the environmental burden from material purchases - mainly concrete and asphalt products - through green purchase plans and eco-design and invest in new machinery powered with cleaner energies such as low-carbon electricity or bioenergies. EEIO analysis also captures impacts often neglected in process-based pavement LCAs - amortization of capital goods, staff consumptions, and services – and shows some substantial impacts advocating for enlarging system boundaries in standard LCA. Yet, pavement construction and maintenance only explain 5% of the life cycle carbon footprint of Canada's road network, against 95% for the roads' usage (72% from vehicle tailpipes releases, 23% for manufacturing vehicles). Thereby, a carbon-neutral pathway for the road industry must first focus on reducing vehicle consumption and wear through better design and maintenance of roads. Finally, EEIO databases and analysis must be developed further as a powerful tool to fight planet degradation, and openIO-Canada must be specifically expanded and refined to allow for more robust and larger multicriteria assessments.

Life cycle assessment and multi-index performance evaluation of semi-flexible pavement after composite modification by using fly ash, rubber particles, warm mixing asphalt and recycled asphalt pavement

Semi-flexible pavement (SFP) has excellent potential to improve pavement performance and durability. This study aims to reduce energy consumption and emissions in the whole life cycle of SFP based on ensuring its good pavement performance through applying fly ash, rubber particles, warm mixing technology, and recycled asphalt pavement (RAP) in SFP. It is observed that after the cement in the cement-based grouting material is replaced and modified with fly ash and rubber particles, the energy consumption and emission of SFP in the whole life cycle are significantly reduced. Compared with the gain effect of energy saving and emission reduction brought by cement replacement, the gain effect of environment-friendly modification of asphalt concrete matrix skeleton is in general. In particular, the application of RAP with high content will instead increase the energy consumption and emissions of SFP in the whole life cycle. At the same time, it is also found that the fatigue resistance of SFP has a significant impact on its energy consumption and emissions. It is a crucial method to reduce the energy consumption and emission of SFP in the whole life cycle to replace and modify the cement in the cement-based grouting materials by using environmentally friendly materials or technologies such as fly ash and rubber particles, and to guarantee or improve the performance of SFP.

Towards the sustainable utilization of steel slag in asphalt pavements: A case study of moisture resistance and life cycle assessment

The large-scale promotion of steel slag (SS) in pavement construction remains challenging due to the concern of swelling potential. This study combined molecular dynamics simulations, surface free energy theory, and X-ray computed tomography to characterize the moisture damage resistance of asphalt mixtures incorporating SS. A case study of the life cycle assessment of SS asphalt pavement under different application strategies (two gradation types and three volume contents) was conducted, including global warming and human-related health impacts. The results indicate the higher polarity and abundant alkaline components of SS contribute to the bonding strength and tend to reduce the moisture susceptibility. The adhesion of steel slag to asphalt is 137.58 %, 120.39 % and 37.06 % higher than that of granite, basalt, and limestone, respectively. The susceptibility index (Energy ratio) is reduced by 108.72 %, 107.90 % and 39.10 %, respectively. Moreover, the incorporation of SS improves the compactness of the structure and delays the penetration and the interconnection between large voids. While the number of micro-voids increases geometrically after steel slag incorporation, ranging from 250 % to 981 % during FT cycles. The proliferation of microdefects has the potential to develop into macro cracks under a long-term freeze-thaw environment, meanwhile the risk of swelling-induced cracks is exacerbated with the high use of SS. The increased consumption of asphalt and transport mass of SS during mixture production are detrimental to the overall environmental impacts. However, the use of SS avoids the damage of exploitation and eliminates the huge risks of landfill accumulation. These two benefits are enormous and cannot be accurately estimated.

Comparative environmental performance of pavement structures considering recycled materials and regional differences

The construction of pavements incorporating reclaimed asphalt pavement (RAP) is taking place around the world, implying the necessity to quantify their net environmental impacts. Life cycle assessment (LCA) is a popular method to analyze the environmental impacts of a product along the whole value chain, providing guidance to practices and technologies from environmental perspectives. However, the LCA research of RAP-modified pavement is seldom performed in Brazil. In addition, as an important source of uncertainties, there is also need of discussion regarding the geographical and technological characteristics in the LCA of pavements. For these motivations, this paper performs a cradle-to-gate LCA to compare the environmental performance of asphalt pavement in Brazil and Switzerland, using the practical rates of RAP use. The functional unit was defined based on the same traffic volume and service life of asphalt pavements, where the mix design and pavement structures follow the standards of the two countries. The results showed that RAP recycling can improve the environmental performance of hot asphalt mixtures in both countries. Binder amount has a high environmental burden and its reduced use by adding RAP has a positive environmental effect. Type of fuel also plays an important role in LCA. In Brazil, it is not recommended to use heavy oils as fuel during the mixing process if other options such as methane gas is available. The results show that the Swiss production of asphalt mixture had lower environmental impact. Nevertheless, a strategic location of material suppliers and mixing plants could lower the transportation distances, improving its environmental performance.

Performance characterization and life cycle assessment of semi-flexible pavement after composite modification of cement-based grouting materials by desulfurization ash, fly ash, and rubber powder

This study aims to carry out the performance characterization and life cycle assessment (LCA) of SFP after composite modification of cement-based grouting materials by desulfurization ash (FGD ash), fly ash, and rubber powder. The results of performance evaluation and scheme optimization of various cement-based grouting materials show that after the synergistic use of desulfurized ash and fly ash, the performance of the mixed cement-based materials is close to that of ordinary portland cement. On this basis, after adding 5 % by weight of rubber powder treated with a 2 % concentration of silane coupling agent (SCA) solution, the strength, toughness, and volume stability of cement-based grouting materials are significantly improved, and the comprehensive performance index can be increased by 70 % or more, and the durability of SFP can be increased by 30 % or more at the maximum. SFP’s energy consumption and emissions are mainly affected by the raw material production stage, in which cement accounts for 90 % or more of the energy consumption and emissions in the raw material production stage. After the reasonable replacement of cement and keeping good durability of SFP, the energy consumption of SFP in the whole life cycle can be reduced by about 30 %, and the environmental impact can be reduced by 30 % ∼ 40 %.

Use of Pavement–Vehicle Interaction-Related Models to Estimate Excess Fuel Consumption of Pavement Alternatives During the Design Stage

The need to quantify the effect of various pavement characteristics on pavement–vehicle interactions (PVI) and the associated excess fuel consumption (EFC) has been identified by practioners of pavement life cycle assessment (LCA), particularly for the use phase. With the current need to reduce carbon emissions, if found to be significant, these effects might also need to be considered by agencies when making investment decisions or when evaluating pavement design and rehabilitation strategies. Several studies have evaluated rolling resistance factors such as pavement roughness, macrotexture, and structural response (SR) to loading to generate models to predict EFC. Available PVI models consider either the effects of pavement surface characteristics (PSC) or SR only, and it is not possible to estimate the total PVI-related EFC using just one model. This paper summarizes a study demonstrating the use of select PVI models for estimating EFC during the pavement design stage for a new construction or reconstruction project and attempts to combine the results of PSC models with SR models to calculate the total contribution of PVI to EFC. The results from the analysis may be helpful for evaluating alternative pavement design strategies, materials, or surface textures for inclusion in the final design and project specifications, provided the gaps and limitations of the models are well understood and considered. The study also identified challenges that might be encountered by agencies in performing such analyses, such as availability of high-quality data for longer analysis periods and lack of measurement methods for ground truth.

Climate change adaptation strategies for Canadian asphalt pavements; Part 2: Life cycle assessment and life cycle cost analysis

Presently, there is strong consensus that significant temperature and weather changes are fast approaching as a result of climate change. Pavements will be significantly affected by increased temperatures, precipitation, and flooding, and will require present design methodology to be modified accordingly. Several climate change adaptation strategies are easily available to agencies including upgraded asphalt binder grades, increased Hot Mix Asphalt (HMA) thickness, modified mix gradations, and stabilized base. The objective of this study is to investigate Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) for climate change adaptation strategies across various locations in Canada, from a Global Warming Potential (GWP) perspective. All analysis was completed leveraging the Athena Pavement LCA software and the LTPP database. The investigated scenarios were (i) a baseline asphalt pavement with no climate change, (ii) a baseline asphalt pavement with climate change, and (iii) an asphalt pavement adapted to withstand climate change, appropriate to the level of changes experienced by the specific location. The study revealed that although there are initial increases in both cost and emission to administer these adaptation strategies, they are offset over the life of the pavements. Increasing the HMA thickness and using stabilized bases were the most expensive and the highest emitting among the investigated strategies, but they are only necessary for extreme coastal climate change regions including British Columbia and Newfoundland. British Columbia is expected to observe a near 30% increase in agency costs to effectively adapt their pavements to climate change. However, these initiatives were found to decrease the overall global warming potential by nearly 10% in comparison to not adapting. The other examined locations, although not returning as drastic of changes, followed similar trends. The conclusions find that climate change adaptation strategies are highly beneficial from the standpoint of both an LCA and LCCA for all of the investigated locations.

Life cycle assessment of eco-friendly asphalt pavement involving multi-recycled materials: A comparative study

In this research, a comparative Life Cycle Assessment (LCA) is conducted to evaluate the environmental potential of utilizing multi recycled materials in asphalt pavement construction. These Materials are Reclaimed Asphalt Pavement (RAP), Off-spec Fly Ash (OFA), and a Food Waste Bio-oil (FWBO). A comparative analysis is performed on producing one ton of asphalt mixture considering multiple scenarios, which stem from virgin materials extraction, recycled materials production, transportation, and asphalt mix production. The study analyzed six percentages of RAP replacement to aggregate and asphalt binder , 0%, 15%, 30%, 50%, 80%, and 100% RAP. Moreover, two proposed products substituted 11% virgin asphalt binder by weight in the different mixtures. The first product is the FWBO, which is utilized alone as an asphalt binder rejuvenator with the highest two RAP rate scenarios: 80 and 100%. The second product is a blend of the OFA with the FWBO with a 2:1 ratio, which is evaluated with all the investigated scenarios. After assessing the baseline scenario, two alternative scenarios are investigated. The first alternative is utilizing natural gas to replace the commonly used Heavy Fuel Oil (HFO) in the asphalt mix production process. The second alternative scenario is changing the FWBO extraction technique from Soxhlet to Ultrasonic Assisted-oil Extraction (UAE). Open-LCA software is used for modeling all the investigated scenarios in the light of TRACI v.2.1 impact assessment methodology in this case study. The results show a reduction in environmental impacts with RAP utilization and the new eco-friendly products. Shifting asphalt mix plant fuel to natural gas instead of HFO offers considerable potential environmental benefits. Adopting the UAE as FWBO rejuvenator extraction method showed less energy and solvent consumption than the Soxhlet extraction, resulting in less environmental impacts.

Environmental trade-offs for using low-noise pavements: Life cycle assessment with noise considerations

Noise mitigation is the main advantage of semi-dense asphalt (SDA) pavements compared to traditional pavements such as stone-mastic asphalt (SMA), but noise is not quantitatively considered in traditional life cycle assessment (LCA). This article performs a comprehensive LCA for SMA and SDA including noise considerations. State-of-the-art sound emission and acoustical ageing models were used to determine the road traffic noise. The latest Swiss dose-response curves and current noise exposure data were used to evaluate health impacts due to noise. Additionally, traditional LCA is also included for assessing the greenhouse gas emissions, non-renewable cumulative energy demand and health impacts of non-noise processes. The results show that SDA causes around 70 % higher greenhouse gases and energy demand than SMA, primarily due to its shorter service life. However, the noise impacts in disability adjusted life years (DALYs) are higher by two to three orders of magnitude than non-noise processes, and the use of SDA can reduce 40 % of the total DALYs. It is shown that road traffic noise plays a significant role in the LCA of pavements. The trade-off between greenhouse gas and energy related impacts, on the one hand, and health effects, on the other hand, requires critical consideration by decision makers when promoting low-noise pavements.

Life Cycle Assessment in Road Pavement Infrastructures: A Review

The need to meet society's demands for road infrastructure while minimizing the resulting environmental impacts is a source of great complications. In this context, Life Cycle Assessment (LCA) can be useful by applying a set of rules and processes for the environmental assessment of projects. The objectives of this study were to present the main environmental impact categories associated with emissions from the life cycle phases of a road pavement and how to estimate them. In addition, this paper provides examples of LCA applications on these infrastructures. In view of the evolution of research on LCA, a compilation was made on: the main categories of environmental impact associated with emissions; phases of life cycle impact assessment; and procedures and methods of impact estimation. The impact categories presented are associated with climate change, acidification, ozone depletion, tropospheric ozone formation, eutrophication, and Particulate Matter Formation. Not all methods are able to generate indicators for all types of impact and, depending on the type of materials and services that make up the inventory of the alternatives analyzed, one specific method may be more appropriate to use. The conclusions are that for each environmental impact, the results depend on the input parameters, such as energy flows and materials, along with their processing by methods of life cycle impact assessment. Besides this, despite the great diversity of the databases for the steps of life cycle assessment of roadway pavement, there is a general consensus about the nature of these steps. Doi: 10.28991/CEJ-2022-08-06-015 Full Text: PDF

Environmental performance evaluation of warm mix asphalt with recycled concrete aggregate for road pavements

ABSTRACT A Life Cycle Assessment (LCA) was undertaken to compare the potential environmental impacts associated with the use of Recycled Concrete Aggregate (RCA) as a partial replacement of natural aggregates in the production of Warm Mix Asphalt (WMA), with those of a conventional Hot Mix Asphalt (HMA). The LCA was conducted according to the ‘cradle-to-laid’ approach, including four pavement LCA phases. Three percentages of RCA replacement for natural coarse aggregates in WMA were considered: 15, 30 and 45%. The results of laboratory tests were used as inputs in the design of pavement structures with different percentages of RCA for typical Colombian pavement design conditions. Primary data and SimaPro 8.4.0 software were used in modelling the processes analysed in the case study. All the life cycle inputs and outputs related to the functional unit were characterised according to the impact assessment methodology TRACI v.2.1. The results show that the potential environmental benefits arising from the combined effect of reducing the consumption of natural aggregates and reduced mixing temperature are offset by the reduced performance and the increased optimum asphalt content when incorporating RCA in WMA. The highest relative increase in the environmental impacts, at 29%, was observed in the Ecotoxicity impact category.

Flexible pavement performance and life cycle assessment incorporating climate change impacts

Construction, maintenance and demolition of pavements are often considered the only activities impacting the environment. This paper shows that user emissions, influenced by factors such as road roughness and climate change, are also important measurements of pavement sustainability . The objective of this paper is to complete a life cycle assessment of a typical flexible pavement based on the climate change forecast by using road deterioration and user emissions analysed with the Highway Development and Management 4 (HDM-4) package. Data from South Africa were used to prove the concept. Results showed that user emissions dominate life cycle environmental impacts , and that gradual warming and drying of the atmosphere attributed to climate change is beneficial to pavement deterioration and emissions alike. Although invariably debate about the impact of climate change has negative connotations, and the reality of many negative impacts, road authorities in South Africa are fortunate that less rainfall will be beneficial.

Integrating sustainability into pavement maintenance effectiveness evaluation: A systematic review

Based on the publications from two databases during 1998–2020, this paper presents a systematic literature review on pavement maintenance effectiveness evaluation to summarize the current trend and identify the research gap that must be addressed for a sustainable maintenance management. This review has analyzed and synthesized maintenance thresholds and their mechanisms, the measurement methods of effectiveness in terms of performance, cost and environmental impacts. In particular, this paper has critically examined the state-of-art maintenance effectiveness optimization strategy that has included environmental concerns and sustainable goals, in comparison with the traditional cost-effectiveness evaluation method. The study has revealed the ambiguous definition of pavement maintenance effectiveness and data availability have caused inconsistencies in the evaluation process; moreover, the embryonic pavement life cycle assessment studies and limited study on pavement use phase have set obstacles in the expanding system boundary of sustainable maintenance effectiveness evaluation.

Vehicle excess fuel consumption due to pavement deflection

The pavement structural rolling resistance (SRR) effect on vehicles' excess fuel consumption (EFC) was investigated. A practical approach was proposed to assess vehicle EFC due to pavement deflection based on the fundamental energy-deformation principles. The proposed model was formulated using a quadratic form of maximum pavement deflection, whose parameters are truck loading and speed and pavement temperature. The proposed model utilizes input used in the current AASHTOWare design methods. This allows the integration of the developed model in pavement design and performance prediction while used in pavement life cycle assessment (LCA). Sensitivity analysis showed the reasonableness of the model over a wide range of loading, temperature, and speed scenarios. The estimated EFC for a heavy truck ranged from 0.03% (half loaded, 0 °C, 115 km/h) and 6.5% (fully loaded, 40 °C, 8 km/h). The truck EFC is highly nonlinear and exponentially grows with decreasing speed and increasing temperature.