METODOLOGIA DI APPROCCIO INTEGRATO SOSTENIBILITA’ – RESILIENZA NELLA RIABILITAZIONE DELLE INFRASTRUTTURE VIARIE DOPO EVENTI ESTREMI

Sustainability and resilience are relevant concepts in design and management of  transport infrastructures. Sustainability refers to concept of development that meets the needs of the present without compromising the ability of future generations to meet their ones. Resilience is linked to the occurrence of extreme events during the life cycle of infrastructures and it is a measure of the ability of recovery the previous functionality. Traditionally, the two concepts are applied separately even if they present a significant number of similar characteristics. The better solutions in transport infrastructures design, maintenance and rehabilitation should lead to an improvement of both qualities. This paper presents an integrated approach sustainability-resilience as a useful tool in the decision-making process where different alternatives of rehabilitation after an extreme event are considered. Sustainability and resilience are estimated based on LCCA. The integrated perspective allows addressing an appropriate amount of technical, economic and environmental issues and is an useful tool for the identification of  the most efficient solution

PAVIMENTAZIONI STRADALI: ANALISI DI CICLO DI VITA E SOSTENIBILITÀ ENERGETICO-AMBIENTALE

Based on the 2030 Agenda for Sustainable Development (25th September 2015), transport systems have to be 1) Sustainable. 2) Quality and resilient. 3) Safe. To this end, note that the Italian Ministry of Research funded the Research Project PRIN USR342 that involves related ideas and focuses on 3 paving solutions (made with recycled materials and sustainable technologies), 4 sets of modules (software), and 2 platforms. The objective of the study here presented deals with the assessment of the best pavement technology based on energy and environmental performance. Consequently, a life cycle assessment, LCA, was applied, considering material production, construction, maintenance, and end of life. The environmental impact of the different pavement technologies was derived. Results demonstrate that the use of warm mix asphalts and of recycled asphalt pavement (RAP) yields the lowest energy consumption and environ-mental impact. Furthermore, under the hypotheses of the study, the production of mixtures is crucial because it corresponds to a contribution of about 60-70% in the life cycle of the different materials. LCA approach confirms as a methodology able to help decision makers when strategies and actions for the eco-design of road pavements are needed

Permeable pavements for storm water control incorporating nano clay

Stormwater affects the economic situation of the environment, changes the land use, which also affects the ecosystem. Consequently, this affects the pavement condition of the road and lead to both structural and functional pavement defects. In a bid to proffer solution to the harmful effects of stormwater and reduce the cost of pavement construction in track with sustainability, this research utilized nano clay in the development of permeable concrete. The nano clay was used as a partial replacement for cement. It was dehydroxylated at 720°C; the characterization and particle geometry was done using the XRF equipment. The de-hydroxylated nano clay was used as a partial replacement for cement at 5, 10, 15, 20 and 25%. Correspondingly, six samples of concrete were developed. The mechanical properties (compressive and flexural strength) of the permeable concrete was assessed at 3, 7, 14, 21 and 28 days. Additionally, the porosity of the concrete was determined using Archimedes principle. The result of the research showed that using nano clay replacement at 15% gave a flexural strength of 4.01MPa. This is lower than the required specification of 4.27Mpa—4.5MPa for pavement construction at 28 days and 4.5Mpa and above for airfield pavement. The porosity test using Archimedes principle showed a satisfactory result. This proves the efficiency of the concrete for stormwater control. Therefore, this concrete is recommended for use in the design and construction of low axle or low trafficked road for stormwater control and aquifer recharge based on the flexural strength

Estimation of Gas and Dust Emissions in Construction Sites of a Motorway Project

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 (NOx), 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 NOx. 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 NOx, 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

Sustainability and Resilience in the Rehabilitation of Road Infrastructures After an Extreme Event: An Integrated Approach

For road infrastructures, the concepts of sustainability and resilience are becoming more and more relevant. The sustainability is closely linked with the concept of development that meets the needs of the present without compromising the ability of future generations to meet their own needs. The resilience is usually connected with the occurrence of extreme events or unusual disturbances (earthquake, landslide, floods) during the life cycle of infrastructures and refers to their ability of recover the previous functionality. Usually, the two concepts that account for two desired qualities of the infrastructures are applied following separate approaches. Better choices in road design, maintenance and rehabilitation should lead to an improvement of both qualities. On the other hand, an in deep analysis of the sustainability and resilience demonstrates a significant number of similar characteristics. In the light of the above premises, in the present paper, the suitability of an integrated approach in the choice of the rehabilitation alternatives after an extreme event is evaluated. A method to assess the sustainability, based on life cycle costs, and to estimate the resilience is setup. It resulted that an integrated perspective can be pursued and both resilience and sustainability allow addressing an appropriate amount of technical, economic and environmental/social issues and can lead to identifying the most efficient solution of rehabilitation

Quantifying the Effect of Present, Past and Oncoming Alignment on the Operating Speeds of a Two-Lane Rural Road

In the last decades several studies were conducted in order to develop operating speed prediction models for two-lane rural roads. Many factors were found to affect the operating speed, such as radius of horizontal curve or curvature changes rate, grade, length of horizontal curve, deflection angle, sight distance, superelevation rate, side friction factor, and pavement conditions. Though this, many issues arise when there is an appreciable and continuous variance of geometric features along the road and, for example, short and long tangents coexist in the same road. In such conditions, assessing homogeneous sections, calibrating robust algorithms aimed at V85 prediction is a severe task and safety goals are not easily achieved. In the light of the abovementioned facts, objective and scopes of this work were confined into the quantifications of the effect of past, present, and future geometric elements on operating speeds. In particular, attention was focused on the consistency of the assumption of an environmental speed as a reference value for both short (dependent) and long (independent) tangents. Authors proposed a new operating speed model in which the geometric features of the previous and oncoming alignment were explicitly considered. The proposed speed prediction algorithm was validated on the basis of a wide experimental survey carried out in a rural road of the Province of Reggio Calabria – southern Italy. Problem modelling, experimental plan and results discussion are reported. Results proved the validity of the proposed model even if further experiments are needed to make the model able to predict the operating speed in different type of roads

LCC-Based Appraisal of Ballasted and Slab Tracks: Limits and Potential

The increase in train speed and axle load is an important goal to achieve in the future.  From a technical standpoint, ballastless tracks seem to be suitable to the aim, especially when high-speed passenger trains share the track with freight trains. Based on the above, the primary objective of this study is the comparison between ballasted and slab tracks regarding total costs over the life course. A suitable model to evaluate the total costs of competing solutions is set up. A solution for solving the issue of CO2 price fluctuation and for the quantification of External Costs is also formulated.  Life Cycle Costs are estimated based on agency, environmental and present user values. Analyses and results show that when Life Cycle Costing-based approaches are applied: i) Agency Costs have to be considered in the long-term perspective; ii) expected life has an appreciable impact and several solutions and systems, more affordable in the short term, yield unfavourable maintenance and renewal processes; iii) if total costs are considered over track life, the breakeven point is very far from the construction. Furthermore, the differences between the total Present Values of the two solutions become too small to yield sound conclusions in favour of the ballasted vs. the ballastless solution

Life cycle cost assessment of bitumen stabilised ballast: A novel maintenance strategy for railway track-bed

In railway sector, the high quality of the track is ensured by adequate construction methods and frequent maintenance. To reduce the maintenance frequency diverse techniques have been recently developed. Among others, bitumen stabilised ballast (BSB) represents an innovative solution designed to increase ballast service life and reduce overall maintenance burdens. This technology, which can be used for new track-beds as well as to reinforce existing ones, consists of the use of bitumen emulsion (BE) poured or sprayed at ambient temperature onto the ballast. The objective of the present work is to assess the economic feasibility, encompassing the estimation of the costs of the environmental impacts, of this innovative technology (BSB), compared to the traditional ballast (TB). This purpose is achieved using a lifecycle approach where economic and environmental impacts are combined to return an integrated model. Results of Life Cycle Cost Assessment carried out for the baseline scenarios (with respect to traffic level and quality level set for the infrastructure) indicated that: the BSB technology, used since the construction stage and during the routine tamping, can provide economical savings. Sensitivity analysis to main parameters affecting results showed that these savings can vary significantly, especially in relation to the traffic and the discount rate

Assessing the Open Trenches in Screening Railway Ground-Borne Vibrations by Means of Artificial Neural Network

Reducing ground borne vibrations in urban areas is a very challenging task in railway transportation. Many mitigation measures can be considered and applied; among these open trenches are very effective. This paper deals with the study of the effect, in terms of reduction of vertical and horizontal displacements and velocities, of the open trenches. 2D FEM simulations have been performed and several open trench configurations have been analysed varying the main geometric features such as width and depth, distance from the rail, thickness of the soil layer over the rigid bedrock, type of the ground, ratio between the depth of the trench, and the thickness of the soil layer. For quantifying the influence of the above specified parameters in reducing ground-borne vibrations an analysis using artificial neural networks (ANNs) has been carried out. Results show that among the geometric parameters the role of the depth of the trench is very significant; however the influence of the depth must be also evaluated in relation to the thickness of the soil layer