Recycled and low-temperature materials are promising solutions to reduce the environmental burden deriving from hot mix asphalts. Despite this, there is lack of studies focusing on the assessment of the life-cycle impacts of these promising technologies. Consequently, this study deals with the life cycle assessment (LCA) of different classes of pavement technologies, based on the use of bituminous mixes (hot mix asphalt and warm mix asphalt) with recycled materials (reclaimed asphalt pavements, crumb rubber, and waste plastics), in the pursuit of assessing energy and environmental impacts. Analysis is developed based on the ISO 14040 series. Different scenarios of pavement production, construction, and maintenance are assessed and compared to a reference case involving the use of common paving materials. For all the considered scenarios, the influence of each life-cycle phase on the overall impacts is assessed to the purpose of identifying the phases and processes which produce the greatest impacts. Results show that material production involves the highest contribution (about 60–70%) in all the examined impact categories. Further, the combined use of warm mix asphalts and recycled materials in bituminous mixtures entails lower energy consumption and environmental impacts due to a reduction of virgin bitumen and aggregate consumption, which involves a decrease in the consumption of primary energy and raw materials, and reduced impacts for disposal. LCA results demonstrate that this methodology is able to help set up strategies for eco-design in the pavement sector.

The performance of railway tracks can be assessed by separately applying different approaches, such as reliability, availability, maintainability, and safety (RAMS) and lifecycle costing (LCC). Results of these approaches are not comprehensive because RAMS management lacks an LCC perspective and balance, whereas LCC develops an economic analysis but does not address specific issues of railway performance. Based on these considerations, this study defines a key performance indicator (KPI) for railway tracks as merging the LCC and RAMS approaches at a given time. Innovative algorithms are set up for LCC, RAMS, and their relationship in the definition of KPI. Algorithms are applied to two different track alternatives (ballasted and ballastless), and the KPI trend over time is assessed. Case study results show that the KPI of ballasted tracks is higher in the short-term, whereas the slab track performs better in the long-term. The trend of KPI for the two solutions under investigation shows that the breakeven point depends on traffic and speed in the railway lines. The method setup as well the results obtained contribute to the body of knowledge of construction engineering because: (1) the equations set up allow deriving agency-based algorithms through calibration; (2) the model set up and implemented allows agencies to handle basic technical instances (e.g., RAMS) and lifecycle-related issues (in which sustainability is considered) in a synergistic and quantitative way; and (3) the previously mentioned KPI has the potential to quantitatively affect decision making across the entire cycle of life (design, maintenance, and renewal).

Rail is expected to become the backbone of future mobility in the world as the cleanest and greenest high-volume transport. Rail generates the lowest CO₂ emissions and energy consumption when in operation, with respect to the other transportation modes, but during construction and maintenance phases, its environmental impacts are significant and need to be carefully assessed and properly mitigated. This paper, through an extensive analysis of the recent literature, aims to provide a comprehensive framework of trends and challenges in railway sustainability, with particular attention paid to track and related materials and components, maintenance strategies, and methods of assessment of sustainability. The followed approach takes into consideration the lifespan of the track and the related main stages. The results show that: (i) several innovative sustainable materials have been introduced with significant environmental performances and limitations, mainly due to the lack of knowledge of long-term mechanical behavior; (ii) appropriate strategies of maintenance, supported by effective monitoring of the track conditions, can reduce negative effects on the environment and society and contribute to making this transportation mode greener; (iii) many devices for the automated detection of the track defects allow increasingly widespread and effective monitoring of the track and are essential means in overcoming the challenge of “smart rails”; and (iv) life cycle assessment (LCA) and circularity metrics are effective and indispensable tools in the decision-making process, since they help to quantify the potential environmental enhancement of different materials and solutions.

Minimizing the environmental impacts is a challenging task to achieve sustainability in road constructions. Although they are only temporary, the environmental burdens of building activities can have a great impact on the environment and communities, and must be properly assessed and mitigated. A comprehensive evaluation of the impacts requires the consideration of all construction activities, construction sites and the type and operation time of off-road machines and plants that will be used in each site. In this paper, a case study relating to the project of a motorway was carried out with the following objectives: (i) to estimate the dust and gases arising from the whole construction process and identify the most critical pollutants in terms of emitted quantity; (ii) to investigate the worksites, activities and processes with the greatest impact from an emissive standpoint, and (iii) to propose a rational approach for designing and putting in place effective mitigation measures. Carbon oxide (CO), nitrogen oxides (NO_x), and fine particulate matter (PM₁₀) emissions have been estimated by applying different models, methodologies and databases, depending on the construction process under analysis, and an emissive balance sheet has been produced. Results showed that CO is the pollutant released in the greatest quantity, followed by NO_x. The emission of PM₁₀, mainly due to the movement of trucks on unpaved roads, is one order of magnitude less with respect to CO and NO_x, but produces the most perceived and undesired effects of the construction process in the interested communities. Tunnels and bridge are the components of a road with the greatest impact in terms of air emissions.

The road sector is one of the main sources of air emissions in the atmosphere during both construction and operation. The objective of the present paper is a comprehensive evaluation of the impact on air quality during the two main phases of life cycle of roads. In this case study of a motorway project, the emissions of the primary pollutants, CO, NOx, and PM₁₀ are estimated, and the results showed that (i) CO and NOx pollutants released during both phases are comparable, while the emissions of PM₁₀ are more significant in the construction phase; (ii) 85% of PM₁₀ in construction is due to storage, transit on unpaved road, and crushing; (iii) the portals of the tunnel are the sites where there are higher concentrations of pollutants in operation; and (iv) the CO concentrations estimated by the dispersion model are strongly influenced by the topography.