Trends and Challenges in Railway Sustainability: The State of the Art regarding Measures, Strategies, and Assessment Tools

Abstract

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.

Experimental Monitoring of Dynamic Parameters of the Sub-Ballast Layers as a Prerequisite for a High-Quality and Sustainable Railway Line

“…Abroad, much attention is now dedicated to the sustainable development of rail transport and saving natural resources. A comprehensive analysis of the trends and challenges in railway sustainability, with a specific focus on materials and components of the permanent way and methods for sustainability assessment, is presented in [17]. The methods for reducing noise emissions and vibrations by rail traffic (construction and legal methods) and an innovative analysis for limiting their impact on natural habitats and forest animal populations are detailed in [18].…”

Evaluating Different Track Sub-Ballast Solutions Considering Traffic Loads and Sustainability

“…As outlined in [2], it serves to protect the subgrade from traffic loads and prevent mud from pumping into the ballast layer by providing separation and drainage for rainwater or groundwater. Numerous studies by researchers [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] have explored sustainable solutions related to geotechnical layers in railway tracks, such as ballast and sub-ballast, with their objectives including (i) enhancing the load-bearing capacity of the railway track, (ii) reducing strains from traffic loads, (iii) repurposing waste materials, (iv) proposing alternative materials, and (v) minimising ballast breakage.…”

“…Indraratna et al [4] investigated the potential of using geogrids and recycled rubber in the ballast layer to enhance the track performance. Giunta [10] evaluated different recycled waste materials as potential solutions to improve the ballast behaviour.…”

“…The authors concluded that this type of recycled aggregate exhibits high quality in terms of durability, hardness, and resistance to abrasion, while also contributing to a reduction in environmental impacts. Giunta [10] also discussed various modern railway engineering sub-ballast sustainable solutions, including the use of alternative materials like cement-reinforced soils and asphalt binder for sub-ballast applications. Indraratna et al [8] investigated the use of recycled rubber tires mixed with gravel as a sub-ballast layer.…”