Integrating vehicle specific power methodology and microsimulation in estimating emissions on urban roundabouts

In this study pollutant emissions were estimated from VSP modal emission rates and the distribution of time spent in each VSP mode obtained from the speed profiles both gathered in the field and simulated in AIMSUN at a sample of urban roundabouts. The versatility of the micro-simulation model for a calibration aimed at improving accuracy of emissions estimates was tested in order to ensure that second-by-second trajectories experienced in the field by a test vehicle through the sampled roundabouts properly reflected the simulated speed profiles. The first results which the thesis will refer, confirmed the feasibility of the smart approach that integrates the use of field-observed and simulated data to estimate emissions at urban roundabouts. It is also revealed friendly in collecting information via smartphone and in the subsequent data analysis and provided suggestions for large-scale data collection through a digital community. Another goal of this research is to investigate about the environmental performance after a conversion of a traditional existing roundabout into a turbo-roundabout. This aspect has been considered a positive approach for a novel attitude in the performance evaluation of road networks to align the infrastructural design with the aim of sustainable and low-emission mobility. The main finding provided from this study is referred to the positive potential of a novel attitude in the conceptualization and performance evaluation of road units in order to align urban infrastructural projects with the worldwide shared long-term ambitions for a low-emission mobility

Estimation of Passenger Car Equivalents for Two-Lane and Turbo Roundabouts Using AIMSUN

The paper addresses issues related to Passenger Car Equivalents (PCEs) at roundabouts. Compared to other road units, the curvilinear elements of roundabout geometric design may impose greater constraints on vehicular trajectories and have a significant effect on the swept envelope of heavy vehicles. Specifically, the aim of the paper is to present the methodological approach which used traffic microsimulation to estimate PCEs. Focus is made on a case study which considered the conversion of a two-lane roundabout into a basic turbo roundabout with comparable size. Empirical capacity functions for both roundabouts were derived as target values to which simulated capacities by lane were compared. In order to estimate the PCEs a criterion of equivalence based on the amount of capacity used by cars and heavy vehicles is presented. AIMSUN allowed to simulate traffic conditions with different percentages of heavy vehicles at both roundabouts. Thus, variation of traffic conditions where mixed fleets operate was explored. A comparison was made between the PCEs estimated for each entry lane characterized by similar mechanism of entry maneuver. The results indicated there is a need to distinguish the impact of heavy vehicles when operational performance of a two-lane roundabout or a turbo-roundabout should be examined. Especially when circulating flows increase, a higher PCE value is expected than the value that the Highway Capacity Manual proposes for roundabouts

The relevance of on-road emission monitoring in different type of roundabouts in rural roads

Road traffic significantly contributes to urban air pollution as means of particulate matter (PM) and nitrogen oxides (NOX) emissions [1]. Despite the deployment of clean powertrains, internal combustion engines are the most widely used technology in the European Union; gasoline- and diesel-fueled represented around 90% of passenger cars sold between 2014 to 2017 [2]. The amount of exhaust gases emitted by motor vehicles depend on speed profile, vehicle type, traffic volumes and intersections [3]. Roundabouts have been considered and built around the world to replace intersections previously controlled by traffic lights as a means of improving operational performance, at least in certain flow range [4]. These latter ones are considered pollution hotspots locations, due to speed changes cycle around them [5] [6]. Despite the demonstrated benefits in terms of traffic flow, delay reducing and safety [7], roundabouts raised some doubts concerning emissions performance [8]. Bearing this in mind, this paper compares vehicle activity and on-road emission data in three different roundabouts in rural roads: a compact two-lane, a multi-lane and a single lane roundabout in Aveiro, Portugal. It was hypothesized that carbon dioxide (CO2) and NOx emissions, engine speed and the relative positive acceleration (RPA) are impacted by the differences in the approaching and conflicting traffic volumes, the volume-to-capacity ratio and the roundabout layout. Input data such as approaching and circulating traffic volumes, and queue length were collected by videos cameras installed at the studied locations. Field measurements were carried out with two light duty vehicles (gasoline and diesel), using a Portable Emissions Measurement System (PEMS) to measure CO2 and NOX volumetric concentrations. Alongside, an OBD-II scan interface record vehicle speed data, engine speed and acceleration. After that, a relationship between congestion level of roundabouts and occurrence of each speed profile (no stop – I, stop once – II and multiple stops – III) was established, using discrete choice models. Finally, discrete choice models obtained from single-lane, compact two-lane and multi-lane roundabouts were compared. The methodology and models developed used in this paper can be applied by simply measuring roundabout traffic volumes by means of discrete choice models that allows simultaneously detecting differences in location and variability characteristics of the distributions of the observations taken at roundabouts. It also allows to identify some relevant operational and design features of a rural roundabout prior its implementation to enhance capacity and emissions fields.publishe

UAV experimentation for pavement distresses detection

In recent years, due to the high costs of traditional road failure detection techniques, the research has focused its attention on the use of the drone for the recognition of deterioration by experimenting with lowcost 3D detection techniques. The use of these techniques allows to carry out monitoring operations according to a structured and effective planning to guarantee the safety of users. The purpose of this paper is to verify the gradient that determines the loss of accuracy of the 3D acquisition as the flight altitude changes. in this way, the practitioner will have a handbook through which he can decide the altitude of the flight to obtain that degree of metric accuracy. The application is conducted within a road inside the University campus using the DJ Mavic pro2 drone

Understanding the current state of practice in the construction and demolition waste sector through the lenses of circular economy: The Italian recycled materials market for the road construction sector

Construction and demolition waste (CeDw) is mainly produced during the construction, demolition, or renovation activities of civil engineering structures and it accounts for a remarkable amount of the total C&Dw generated, as it is estimated to be around 30%. This proportion differs between countries belonging to different types of economies and tends to be greater in countries with developing economies reaching 74% of total annual production. There is a plethora of applications that C&Dw can be used for under a circular economic model and in this research a focus is being given in the exploitation of C&Dw within the pavement engineering sector, and more specifically, in the utilization of said waste in road earthworks. Circular Economy can act as a steppingstone towards the uptake of C&Dw recycling and exploitation. To understand the state of practice that exists, a market and an implementation analysis have been conducted in Italy. The current applications of C&Dw recycling into road projects were analyzed along with the existing regulations, and local producers. The results projected the various challenges faced by the involved stakeholders, along with the barriers that hinder the wide recycling of C&Dw in road engineering projects. Finally, the proposed national action plans are analyzed and the future potential exploitation of C&Dw is put into context. The future of the specific research is going to involve a full scale, on-site implementation of C&Dw in a defined road segment

A Top-Down Approach Based on the Circularity Potential to Increase the Use of Reclaimed Asphalt

Resource depletion and climate change, amongst others, are increasingly worrying environmental challenges for which the road engineering sector is a major contributor. Globally, viable solutions that comply with the principles of circular economy (CE) are being investigated that can replace conventional asphalt mixtures in a post-fossil fuel society. The use of reclaimed asphalt (RA) is a widely used and well-established method to reduce the environmental and economic impacts of asphalt mixtures while increasing their circularity. However, RA's market supply and demand have not yet been systematically analyzed and established. Moreover, the actual circularity potential and the opportunity of re-circulating RA in a closed-loop model have not yet been methodically defined. To address this, a three-layered framework to quantify and assess the circularity potential (Ω) of RA has been developed. To give stakeholders and legislative bodies a simple method to assess the opportunities available to them to become “more circular”, a novel equation has been formulated. This takes the form of a three-level indicator that considers: technical aspects, the effect of the RA market, and the legislative restrictions. A case study in Germany was structured and undertaken to develop and verify the proposed approach. The results indicate that the available RA is insufficient to cover the needs of asphalt mixture production; even though RA production is significantly lower than the actual need of asphalt mixtures, it is not utilized in its entirety. An impactful step forward is the alteration of the regulations to support the higher utilization of RA in asphalt mixtures, and subsequently, the increased circular opportunity and potential of RA. Thus, Circularity potential (Ω) is a composite indicator that can support stakeholders, designers, and asset managers during the process of decision-making, to follow more circular operational, design, and asphalt pavement management patterns

ISIM - INFRASTRUCTURES & STRUCTURES INFORMATION MODELING: A NEW CONCEPT OF BIM FOR INFRASTRUCTURES

The application of Building Information Modeling (BIM) in infrastructure and structural projects, known as Integrated Structural and Infrastructure Modeling (ISIM), has gained attention in recent years due to its potential to revolutionize the construction industry. By providing a digital representation of the built environment, BIM allows for improved collaboration and communication between project stakeholders, leading to enhanced project outcomes. The ISIM approach is centered on the creation of a digital twin, a three-dimensional model of the infrastructure or structure, which serves as a virtual replica of the physical asset. This digital twin provides a platform for analysis, decision-making, and management throughout the project lifecycle, from design and construction to operation and maintenance. One of the key benefits of the ISIM approach is the ability to optimize the construction process, reducing costs, and improving efficiency. The digital twin allows for the identification of potential issues in the design phase, enabling them to be addressed before construction begins. The model can also be used to simulate different scenarios, providing insights into the most effective construction methods, sequencing, and scheduling. Additionally, the use of ISIM can facilitate collaboration and communication among project stakeholders, including architects, engineers, contractors, and owners. The digital twin provides a shared platform for all stakeholders to access and contribute to, allowing for real-time feedback and decision-making. This increased collaboration can lead to reduced errors, improved quality, and enhanced project outcomes. In this paper the authors propose the example of the Meier bridge in Alessandria starting from the 2D drawings to create the 3D model and link it to the external context using Autodesk Infraworks software. A virtual reality implementation has been considered as useful tool to improve the maintenance management

Assessing the Environmental Performances of Urban Roundabouts Using the VSP Methodology and AIMSUN

In line with globally shared environmental sustainability goals, the shift towards citizen-friendly mobility is changing the way people move through cities and road user behaviour. Building a sustainable road transport requires design knowledge to develop increasingly green road infrastructures and monitoring the environmental impacts from mobile crowdsourced data. In this view, the paper presents an empirically based methodology that integrates the vehicle-specific power (VSP) model and microscopic traffic simulation (AIMSUN) to estimate second-by-second vehicle emissions at urban roundabouts. The distributions of time spent in each VSP mode from instantaneous vehicle trajectory data gathered in the field via smartphone were the starting point of the analysis. The versatility of AIMSUN in calibrating the model parameters to better reflect the field-observed speed-time trajectories and to enhance the estimation accuracy was assessed. The conversion of an existing roundabout within the sample into a turbo counterpart was also made as an attempt to confirm the reproducibility of the proposed procedure. The results shed light on new opportunities in the environmental performance evaluation of road units when changes in design or operation should be considered within traffic management strategies and highlighted the potential of the smart approach in collecting big amounts of data through digital communities

Environmental Performance Evaluation at Urban Roundabouts

Transformation toward greener, healthier and safer management of urban mobility demand is needed soon. Smart tools are available to assess the impact of new infrastructural projects and road facilities also from an environmental point of view. In this pilot study pollutant emissions at a sample of urban roundabouts were estimated employing the Vehicle Specific Power methodology which needs second-by-second speed profiles both gathered in the field and simulated in AIMSUN. The versatility of the micro-simulation model for a calibration aimed at improving accuracy of the emissions estimates was tested in order to ensure that second-by-second trajectories experienced in the field properly reflected the simulated speed-time profiles. The results confirmed the feasibility of the smart approach that integrates the use of fieldobserved and simulated data to estimate emissions at urban roundabouts. It is also revealed friendly in collecting information via smartphone and in the subsequent data analysis, and provided new opportunities for a large-scale data collection through a digital communit