The integration of buses with a high level of service in the medium cities urban context

In the last decade the world has witnessed a large diffusion of the BHLS (Buses with a High Level of Service) systems. This growth was sparked off by the successful implementation of the first BHLS system in Curitiba (Brazil) in the 1970s, also named bus rapid transit (BRT), which was able to achieve reliable and efficient transport service at reduced costs. The main reason of BHLS’ spread is mostly due to its proper characteristics that allow to combine flexibility and low costs typical of bus based systems with reliability, efficiency, speed, frequency, comfort and safety offered by the more costly LRT (Light Rail Transit).These systems are generally characterized by modern environmentally-friendly vehicles, reserved bus-ways and applications of intelligent transport systems (ITS) based technologies. All these characteristics are very important features of the so-called smart mobility. The aim of this paper is to describe the working process adopted to design a new BHLS line haul in Pisa (Italy) connecting Pisa Central Railway Station with the Hospital of Cisanello. The paper shows how the new BHLS line could be fairly suited to the Italian context, and in particular to a medium sized city like Pisa, characterized by narrow streets, high density of building and need of sharing large part of bus paths inmixed traffic. Furthermore, this paper evaluates the feasibility of a solution to solve the problem concerning the give-bus priority.Signalized roundabouts with controlledtraffic light and giving priority to BHLS vehicles, that allow buses to cross the intersection without stopping delays, have been proposed. The results of such design analysis on one side confirm line haul feasibility, and on the other side show that the expected level of service of the proposed design solutions is fairly good. Finally, some brief considerations are also drawn on BHLS transit general features giving design insights in respect to a mid-size urban area requirements

A comparative environmental impact analysis of asphalt mixtures containing Crumb Rubber and Reclaimed Asphalt Pavement using Life Cycle Assessment

Recently, the reduction of the environmental burdens related to highway infrastructures has been in the spotlight. Within this context, the use of recycled materials in bituminous mixtures for road pavement construction and maintenance has the potential to mitigate the excessive use of non-renewable resources. Nevertheless, the material consumption is only one of the aspects that affects the sustainability of an infrastructure. Other relevant aspects related to environmental issues should be considered. The objective of this work is to evaluate the potential environmental impacts of asphalt mixtures containing crumb rubber (CR) (vulcanised or devulcanised) and reclaimed asphalt pavement (RAP) assuming different Degree of binder Activation (DoA) of the aged binder by means of a life cycle assessment (LCA). The results show that the small amount of CR used for bituminous mixtures application does not justify all the additional consumption of resources and emissions associated with its treatment. These results are explained by the higher environmental impacts stemming from the treatment of the rubber and the higher amount of bitumen employed in the mixture. In turn, for mixtures containing RAP the analysis revealed an improvement in the score of all the environmental indicators considered.This is the peer-reviewed version of the article: S. Bressi, J. Santos, M. Orešković, and M. Losa, ‘A comparative environmental impact analysis of asphalt mixtures containing Crumb Rubber and Reclaimed Asphalt Pavement using Life Cycle Assessment’, International Journal of Pavement Engineering, 2019, [https://doi.org/10.1080/10298436.2019.1623404

Analisi di un sistema di trasporto pubblico a guida vincolata a servizio di un'area vasta

I sistemi di trasporto pubblico a guida vincolata, avendo costi di investimento significativi, sono solitamente utilizzati per soddisfare la domanda di mobilità delle grandi aree metropolitane. Negli ultimi anni, lo sviluppo di centri urbani limitrofi di medie dimensioni ha determinato la formazione di aree abitate molto estese risultanti dalla espansione di tali centri sino a formare degli agglomerati urbani senza soluzione di continuità. Tali realtà vengono chiamate “aree vaste” per indicare che si tratta di aree appartenenti a comuni diversi e fra le quali vi è una significativa interazione di tipo socio-economico. In conseguenza di questa forte interazione, all’interno delle aree vaste si genera una domanda di mobilità considerevole, dovuta al fatto che un grande numero di passeggeri deve spostarsi su distanze di qualche decina di chilometri. In questi contesti, un sistema di trasporto collettivo a guida vincolata può diventare competitivo rispetto ad un tradizionale sistema di trasporto su gomma. L’obiettivo del lavoro proposto è l’analisi delle caratteristiche, dei problemi di progetto e della convenienza finanziaria di un sistema di trasporto pubblico di massa a guida vincolata che si sviluppa in parte su linea tranviaria e in parte su linea ferroviaria a servizio di una “area vasta”. L’analisi è stata eseguita su un caso prototipale, individuato dall’”area vasta” formata dalle città di Pisa e Livorno, per cui è proposto un veicolo innovativo, il tram-treno: in grado di circolare sia su binari ferroviari sia tranviari. Sulla base di un’analisi della domanda di mobilità all’interno dell’”area vasta”, sono state individuate le parti del territorio da servire con il nuovo sistema di trasporto e sono state definite le caratteristiche progettuali del sistema. Per valutare la redditività della gestione del nuovo sistema di trasporto è stata eseguita un’analisi finanziaria che, in particolare, ha messo in evidenza i valori positivi del margine operativo lordo

Microstructure and rheological response of laboratory-aged SBS-modified bitumens

Polymer additives are widely used to improve the performance of road bitumens including their resistance to hardening during oxidation, although their oxidative inhibitor effect has not been well documented. This study aims to investigate the effect of laboratory-simulated ageing on the microstructure, and rheological properties of Polymer Modified Bitumens (PMBs) prepared with a Styrene-Butadiene-Styrene (SBS) copolymer and sulphur as a cross-linker. The laboratory ageing was conducted through the Rolling Thin Film Oven (RTFO) and the Pressure Aging Vessel (PAV) procedures. The unaged and aged binders were characterised using the Multiple Stress Creep and Recovery (MSCR) test, Gel Permeation Chromatography (GPC) and fluorescence microscopy. The MSCR test showed that the cross-linked polymer had a higher capability of mitigating the effect of bitumen hardening on the rheological response, while for the PMBs without cross-linking, the polymer effects decreased significantly after RTFOT ageing. The GPC results showed that the aromatics, resins and asphaltenes fractions of the unmodified bitumens shifted towards heavier molecules after one cycle of PAV ageing but showed limited variation with further ageing. Similar behaviour was observed for the uncross-linked polymer binders, while for the cross-linked polymer binder, the behaviour depended on the polymer concentration

A procedure for validating fixed-base driving simulators

This paper aims to define a standard procedure for validating a fixed-base driving simulator to be used for road safety studies and in the automotive field for development of new vehicle-subsystems. The driving simulator was developed at the University of Pisa (Italy) – Department of Mechanical, Nuclear and Production Engineering; it is characterized by a static cockpit and a single front projection channel, with vehicle and pedestrian traffic opportunely generated. The validation procedure consisted in a statistical comparison between data recorded by an instrumented vehicle on an urban path and those recorded by the driving simulator on the same path reproduced in virtual reality. A sample of 93 volunteers were submitted to both the drive tests during which several vehicle signals, such as speed data, acceleration, braking action, engine RPM and steering angle were continuously stored. Speed and acceleration data were subsequently analysed through conventional statistical methods (z-test); in order to evaluate differences between real and simulated driving, the statistical analysis was integrated by regression techniques. The analysis allowed to highlight the efficiency of the procedure in both the relative and absolute validation process as well as to evaluate potentials of the specific driving simulator. The procedure has general validity and can be used as a standard procedure for validation of fixed-base driving simulators

Applicability of time-temperature superposition for laboratory-aged neat and SBS-modified bitumens

© 2020 Elsevier Ltd The applicability of the time–temperature superposition principle (TTSP) can breakdown in the case of highly oxidized bitumens and polymer-modified bitumens (PMBs). This study investigates such problem in Styrene Butadiene Styrene (SBS) modified bitumens subjected to high oxidative laboratory-aging levels. The effects of aging were investigated by gel permeation chromatography (GPC), fluorescence microscopy (FM), and linear viscoelastic rheological characterization. As expected, the GPC and FM showed, respectively, an increase in the heavy fractions of bitumen and the degradation of the polymer morphology. Both the phenomena affected the rheological response provided in the form of black diagrams and isochrones of the loss tangent. Neat bitumens demonstrated thermorheologically simple behavior with some very slight symptoms of TTSP breakdown only at very high levels of aging. On the other hand, the applicability of TTSP to PMBs depends on the polymer content and the aging level. Low-medium and medium–high polymer contents PMBs produce minor concerns for TTSP irrespective of the aging level. However, high polymer contents may induce a TTSP breakdown mainly in unaged PMBs with the degradation of the polymer backbone due to oxidative aging progressively restoring a thermorheological simple configuration

Effect of ageing on the morphology and creep and recovery of polymer-modified bitumens

Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the multiple stress creep and recovery (MSCR) test. The results show that the morphology of the SBS modified bitumen degrades with ageing as a function of polymer concentration and dispersion, with higher dispersion being more resistant. The morphology of the EVA modified bitumen has a low ageing susceptibility irrespective of polymer concentration. The MSCR response of EVA modified bitumens does not differ from that found for unmodified bitumen, where the hardening produces a decrease in the non-recoverable compliance. In the case of SBS modified bitumen, the degradation of the polymer backbone affects the bitumen hardening as much as the polymer phase dispersed and networked in the bitumen phase. Furthermore, in the case of the elastomer, the average percent recovery is in agreement with the variation of the morphology with ageing. Therefore, the use of the average percent recovery as a valuable rheological index of the integrity of the polymer network can be advocated

Non-functioning pituitary adenoma database: a useful resource to improve the clinical management of pituitary tumors

Objective: The long-term outcome of non-functioning pituitary adenoma (NFPA) patients is not clearly established, probably due to the low annual incidence and prolonged natural history of these rare tumors. The aim of this study was to evaluate clinical data at presentation and long-term post-surgery and radiotherapy outcome in a cohort of patients with NFPA. Design and methods: A computerized database was developed using Access 2000 software (Microsoft Corporation, 1999). Retrospective registration of 295 NFPA patients was performed in seven Endocrinological Centers of North West Italy. Data were analyzed by STATA software. Results: The main presenting symptoms were visual defects (67.8%) and headache (41.4%) and the most frequent pituitary deficit was hypogonadism (43.3%), since almost all tumors were macroadenomas (96.5%). Surgery was the first choice treatment (98% of patients) and total debulking was achieved in 35.5%. Radiotherapy was performed as adjuvant therapy after surgery in 41% of patients. At the follow-up, recurrence occurred in 19.2% of patients without post-surgical residual tumor after 7.5 ± 2.6 years, regrowth in 58.4% of patients with post-surgical remnant after 5.3 ± 4.0 years and residue enlargement in 18.4% of patients post-surgically treated with radiotherapy after 8.1 ± 7.3 years. Conclusions: Our database indicates that the goal of a definitive surgical cure has been achieved during the last decade in a low percentage of patients with NFPA. This tumor database may help to reduce the delay between symptom onset and diagnosis, to assess prognostic parameters for the follow-up of patients with different risk of recurrence and to define the efficacy and safety of different treatments and their association with mortality/morbidity