33,152 research outputs found

    Road Pricing: Old Beliefs, Present Awareness and Future Research Patterns

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    The theoretical evolution of academic beliefs and practical policymakers' perceptions of road pricing (from now on rp) as an instrument of efficient and equitable allocation of resources are described and analysed. The aim of the paper is to reconstruct the logical evolution of the theory behind rp in order to understand why there has been scarce policy impact in spite of a long theoretical tradition. In so doing I try to bring to the fore the fundamental issues that will have to be tackled by future research in order to generate consensus around this policy instrument. The paper is structured in four parts. In the first part the fundamental issues of a typical rp model are considered. Among the most important aspects one recalls: first-best/second-best environment, short/long term analysis, homogeneous/heterogeneous time evaluation, perfect/imperfect information, efficiency/equity analysis, use/non-use of resources generated, private/public transportation provision. In the second part the characterising parameters have been interpreted in the light of the Smeed Report of 1964 that can be considered representative of the "old belief". In the third part the "present awareness" is expressed by an analysis of the main contents of the book Internalising the Social Costs of Transport of 1993. In the fourth part some reflections on the most promising research areas for rp implementation and acceptance are put forward. Specific research will have to be conducted concerning social acceptability and feasibility, simultaneous cost internalisation, behavioural assumptions, information and pricing interconnections.Road pricing, Social Acceptability, Congestion, Congestion charging

    THE PUBLIC TRANSIT SYSTEMS IN ITALY: A CRITICAL ANALYSIS OF THE REGULATORY FRAMEWORK

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    In this paper we attempt to shed some light on the way the regulation of public transit systems has been approached in the past and is presently addressed in Italy. The reduction of x-inefficiency represents a great challenge for the local authorities, given the high operating costs faced by the transportation companies and the moderate tariffs level that do not allow the operators to balance costs and revenues. Throughout the 1980’s and the first half of the 1990’s, the problem was essentially met by means of stopgap measures taken mainly for emergency, to curb the deficit build-up. In the past five years it has been turning the efforts towards a radical reorganization of the whole local public transportation (LPT) industry, with the law 549/95, completed with the Decreti Legge 422/97 and 400/99. The reform process includes among its goals the attribution of financial responsibility to the sector operators and the start of privatization of the public transit systems. The introduction of more competitive environment, mainly by the resort to tendering for the allotment of concessions, represents the challenge for the future. A complete evaluation of the achieved results is probably still premature. Nevertheless, as the first goal is concerned, the reform appears suitable to yield some positive result. On the contrary, the liberalization and privatization of the LPT sector is progressing very slowly, due to the protection still given to the public-owned companies. It is then expected that in the future a decisive action with regard to such important aspects of the regulatory reform will be undertaken.

    Sampietrini stone pavements: Distress analysis using pavement condition index method

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    In several Italian cities, it is possible to find historical pavements such as the Sampietrini pavements, which are mainly located in the center of the city of Rome. The Sampietrini pavement is a particular road surface paved in natural stone with irregular sharp elements that are assembled by hand with the evident not plan effect. Because of their peculiarities, they are not suitable for streets where high speed is allowed. In many cases, high vibration and noise levels due to road traffic traveling on Sampietrini pavements are caused by inadequate maintenance, which is also affected by the absence of specific evaluation criteria regarding surface conditions and performances of Sampietrini pavements. It is not possible, in fact, to adopt common approaches developed to be used for flexible and rigid pavements, because they present completely different features and distresses. In this paper, to overpass this problem, a new evaluation criterion based on Pavement Condition Index (PCI) method established for block pavements is proposed. Furthermore, to fully characterize this kind of pavements, other analyses, i.e., International Roughness Index (IRI) and comfort level evaluation based on ISO 2631 standard, were also carried out. The results showed a good correlation between PCI and IRI approaches (R 2 = 0.82), also highlighting that new or reconstructed Sampietrini pavements present not negligible roughness level. This aspect was also confirmed estimating the comfort level perceived by users traveling at several speeds (≤50 km/h). Finally, speed related threshold values to be adopted for PCI and IRI methods are proposed. The proposed method can be implemented by pavement managers in a PMS ad hoc for stone block paving and thus, it can be integrated with other equivalents methods of visual inspection based on PCI

    Influence of experimental conditions on sound pleasantness evaluations

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    ICA 2016, 22nd International Congress on Acoustics, BUENOS AIRES, ARGENTINE, 05-/09/2016 - 09/09/2016Being able to characterize and estimate the urban sound perception is a key point to improve the city dwellers environmental quality. In the past decade, various studies have focused on collecting perceived global sound pleasantness at specific locations. Some of them were carried out on field in order to evaluate the soundscape perception of the participants directly in their context. Other studies were realized in laboratory to better control the stimuli and to increase the number of participants who were subjected to the same sound environment. Most of the laboratory experiments are done in large or semi-anechoic chamber with calibrated and highly realistic audio reproduction in order to respect the ecological validity of the experiment. On one hand, even with a high immersive level, the laboratory context is not as rich as the field context and the two types of experiment could lead to different results. On the other hand, few studies exist showing the influence of decreasing ecological validity for the same experience. This work presents a short statistical analysis of perceptive evaluations of ten urban locations under 4 different test conditions. First, evaluations are carried out directly in-situ in the city of Paris. Then audio-visual recordings of these locations are evaluated in three different experimental conditions: (i) in a well-controlled acoustic laboratory in Paris region with French people, (ii) in an acoustic laboratory in Buenos Aires with Argentinean participants and lowest immersive conditions, (iii) in a habitational room with Argentinean participants and subjective calibration. The study reveals that both the 'country' factor and the experimental conditions in laboratory do not show any significant impact on the perceived sound pleasantness and perceived loudness assessments

    The impact of reduction in the benzene limit value in gasoline on airborne benzene, toluene and xylenes levels

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    Background benzene, toluene, xylenes (BTX) average concentrations have been measured over the urban agglomeration of Toulouse, France, during both springtime and summer periods of 1999 and 2001. The benzene average amount over the two Toulouse campaigns in 1999 is equal to 2.2 Ag/m³, very close to the French air quality standard and well under the average value of 5 Ag/m³ recommended by European Economic Community countries, recognising that those regulations are given for a whole year. BTX pollution over Toulouse has, in particular, been produced by motor vehicle exhaust gases. For the study conducted during the same periods of 2001, benzene concentrations were within the French quality value in the whole area. This is because the benzene limit value contained in gasoline went from 5% to 1% since 2000 January 1. It will be important to measure benzene over annual periods in order to know its exact values over such a period and to observe its potential seasonal variations

    How to monitor sustainable mobility in cities? Literature review in the frame of creating a set of sustainable mobility indicators

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    The role of sustainable mobility and its impact on society and the environment is evident and recognized worldwide. Nevertheless, although there is a growing number of measures and projects that deal with sustainable mobility issues, it is not so easy to compare their results and, so far, there is no globally applicable set of tools and indicators that ensure holistic evaluation and facilitate replicability of the best practices. In this paper, based on the extensive literature review, we give a systematic overview of relevant and scientifically sound indicators that cover different aspects of sustainable mobility that are applicable in different social and economic contexts around the world. Overall, 22 sustainable mobility indicators have been selected and an overview of the applied measures described across the literature review has been presented

    Modeling and Design of Millimeter-Wave Networks for Highway Vehicular Communication

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    Connected and autonomous vehicles will play a pivotal role in future Intelligent Transportation Systems (ITSs) and smart cities, in general. High-speed and low-latency wireless communication links will allow municipalities to warn vehicles against safety hazards, as well as support cloud-driving solutions to drastically reduce traffic jams and air pollution. To achieve these goals, vehicles need to be equipped with a wide range of sensors generating and exchanging high rate data streams. Recently, millimeter wave (mmWave) techniques have been introduced as a means of fulfilling such high data rate requirements. In this paper, we model a highway communication network and characterize its fundamental link budget metrics. In particular, we specifically consider a network where vehicles are served by mmWave Base Stations (BSs) deployed alongside the road. To evaluate our highway network, we develop a new theoretical model that accounts for a typical scenario where heavy vehicles (such as buses and lorries) in slow lanes obstruct Line-of-Sight (LOS) paths of vehicles in fast lanes and, hence, act as blockages. Using tools from stochastic geometry, we derive approximations for the Signal-to-Interference-plus-Noise Ratio (SINR) outage probability, as well as the probability that a user achieves a target communication rate (rate coverage probability). Our analysis provides new design insights for mmWave highway communication networks. In considered highway scenarios, we show that reducing the horizontal beamwidth from 9090^\circ to 3030^\circ determines a minimal reduction in the SINR outage probability (namely, 41024 \cdot 10^{-2} at maximum). Also, unlike bi-dimensional mmWave cellular networks, for small BS densities (namely, one BS every 500500 m) it is still possible to achieve an SINR outage probability smaller than 0.20.2.Comment: Accepted for publication in IEEE Transactions on Vehicular Technology -- Connected Vehicles Serie
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