• Energy Research

Several studies evaluated the feasibility of using residues to compose asphalt mixtures. However, the demand for treatments are often neglected in determining the environmental impacts. This study ...

Traffic contributes nearly 25% of global greenhouse gas emissions. For designing new traffic routes and decision-making processes, it is essential to incorporate integral life cycle assessments (LCAs) to ensure sustainable solutions and to achieve the UN Sustainable Development Goals (SDGs). This study compares two fictitious routes: a typical Austrian mountain pass road (Route A) with a 3% gradient and a new route (Route B) featuring a 1000 m tunnel, reducing distance and inclines. The LCA analyzes Route B’s lifecycle, from material supply to 100-year tunnel usage, comparing it against a traffic LCA of Route A’s operational emissions. The tunnel assessment considers the New Austrian Tunneling Method, local materials, and typical geology. Traffic effects are analyzed using Austrian vehicle stock data, following EN 17472 and EN 15804 standards. The results, based on Global Warming Potential, indicate that Route B’s construction, maintenance, and utilization generate lower environmental impacts than Route A’s traffic emissions. The tunnel offers overall environmental savings, with its construction and maintenance impacts offset within approximately 10 years. Traffic usage is identified as the primary long-term emission source. This research highlights the significance of integral LCAs in creating a sustainable built environment and supporting a decision-making process in transport infrastructure construction.

This study applies the life cycle assessment methodology to evaluate the environmental impacts of shock-absorbing pavements fabricated with recycled materials (crumb rubber and a colored pigment called ferrotone), employing the “cradle-to-grave” approach, in which the impacts of all life cycle phases (from materials’ acquisition to the end-of-life of the pavement) are included. The analysis compares the impacts of standard and innovative asphalt materials, considering cold and hot production processes. In addition, three different lifespans are simulated for the pavement structures: the reference service life until the first intervention is considered to be 5 years, and the following scenarios consider that the alternative asphalt materials may last 20% less (4 years) or 20% longer (6 years) than the reference service life. The analysis uses non-renewable cumulative energy demand (nr-CED) and global warming potential (GWP) as main indicators to determine the environmental impacts over a 45-year analysis period. The results show that adopting the “dry process” (consisting of adding the rubber as a partial substitution for aggregates) increases the overall impacts due to the need for higher contents of binder. However, if the alternative pavement structures last 20% longer than the reference, they would generate lower impacts in terms of nr-CED and GWP.

This study used a cradle-to-cradle Life Cycle Assessment (LCA) approach to evaluate the environmental potentials of urban pavements. For this purpose, the urban road network of the City of Münster (Germany) was selected as the case study, and comprehensive data for several phases were collected. The entire road network is composed of flexible pavements designed according to specific traffic loads and consists of main roads (MRs), main access roads (MARs), and residential roads (RSDTs). Asphalt materials, pavement structures, and maintenance strategies are predefined for each type of road and are referred to as “traditional” herein. Some pavement structures have two possible maintenance strategies, denoted by “A” and “B”, with distinguished periods of intervention. To evaluate the impact of using recycled materials, we considered alternative pavement structures composed of asphalt materials containing a greater amount of reclaimed asphalt pavement (RAP). The study was carried out considering analysis periods of 20, 50, 80, and 100 years and using two indicators: non-renewable cumulative energy demand (nr-CED) and global warming potential (GWP). The results show that the use of higher amounts of RAP can mitigate negative environmental impacts and that certain structures and maintenance strategies potentially enhance the environmental performance of road pavements. This article suggests initiatives that will facilitate the decision-making process of city administrators to achieve more sustainable road pavement constructions and provides an essential dataset inventory to support future environmental assessment studies, particularly for European cities.

Almost 25% of the environmental pollution, measured by the indicator of global greenhouse emissions, is emitted by transport. Changes in the mobility behavior of the population will be essential if the 17 UN Sustainable Development Goals (SDGs) and the goals of the EU Commission’s Green Deal are to be attained. Accordingly, the existing infrastructure has to transform into a sustainable transport infrastructure through further optimizations in the future. Therefore, continuous optimizations and improvements of designs, materials, and processes are crucial to achieving long-term sustainability. This study investigates different superstructures with the method of life cycle assessment using the example of the emerging high-performance infrastructure at the Brenner Base Tunnel (BBT). The study analyzes all relevant life cycle stages (A1–C4) and validates different effects of service lifetimes of superstructure elements on the open track and in the tunnel. The results, which are presented in the form of GWP, AP, and NRCED, show that there is environmental reduction potential, especially in the stage of use. As more frequent modernization cycles and the associated remanufacturing of superstructure elements account for a significant proportion of the total environmental impact, lifetime extending optimization of products yields improvements in the ecological footprint.

Previous studies of road or railway infrastructures have shown that traffic emissions outweigh the environmental impacts of the product stage and construction stage over the entire life cycle. Traffic usage is therefore the main emitter over the life cycle (A1–C4). Due to the small number of sustainability assessment systems, the question of how to consider traffic emissions in detail in an integral life cycle assessment has arisen. This study examines Austrian car traffic and investigates environmental impacts beyond the scope of carbon dioxide and particulate matter. The results were determined for a selection of common impact indicators. In addition to driving in flat terrain, an approach is presented that enables the evaluation of emissions due uphill and downhill driving. Thus, route options and route closures/detours due to maintenance work can be evaluated in a simple way. During the analyses, a traffic calculator was developed, which can currently assess different cars depending on the route specifics (flat/hill). The tool can be expanded to include other road vehicles (buses, trucks, motorcycles) and trains as well. This will simplify evaluations and decision-making processes and provide optimal support for a future-proof sustainable built environment.

This paper applies the Road Network Evaluation Tools (RONET) model to assess the economic impacts of urban pavement maintenance and rehabilitation in the city of Munster, Germany. The city’s road network includes main roads, main access roads, residential roads, and paved areas for pedestrians, cyclists, and parking spaces. The specific traffic loads applied to Munster’s network demand several different pavement materials, structures, and intervention procedures. This study aims to support stakeholders’ decision-making by assessing current expenditures, network conditions, and country-specific data to determine the appropriate financial allocation for recurrent maintenance, periodic maintenance, rehabilitation, and new pavement construction. Six scenarios comprising distinct pavement structures and maintenance strategies are modeled in RONET to perform the analysis. The outcomes include the future deterioration of pavements under different maintenance scenarios, the current and projected asset value of the network, and the total costs (road agency costs + user costs) of the network to society, considering each scenario being applied over a 20-year evaluation period. The RONET model also provides the annual average cost of each maintenance procedure and the additional costs to society while using a budget scenario other than ‘Optimal.’ The results indicate that Munster’s current investment program is in line with the ‘Optimal’ budget scenario proposed by RONET. In addition, the model suggests that performing recurrent and periodic interventions is more cost-effective than neglecting the conservation of pavements for an extended period and endorsing more extensive interventions in the future, such as rehabilitation or reconstruction.