Search results for "TRADE"
showing 10 items of 1475 documents
Improving the sustainability of transportation: environmental and functional benefits of right-turn by pass lanes at roundabouts
2015
The functional performances of conventional roundabouts (single-lane and multi-lane) and innovative roundabouts (spiral, flower, C and turbo) can be improved through right-turn bypass lanes controlled by stop, yield or free-flow signs. The article presents evaluations of the emissions of air pollutants (carbon dioxide, nitrogen oxides, particle pollution (PM10 and PM2.5)), fuel consumption and construction, management, energetic and environmental costs in roundabouts without or with bypass lanes (controlled by stop, yield or free-flow). The suggested methodology has a general character and can be applied as a multi-parametric criterion for choosing road intersections, although, in the prese…
Towards 100 % recycling of reclaimed asphalt in road surface courses: binder design methodology and case studies
2016
Reclaimed Asphalt (RA) has shown great potential to be reused in new asphalt mixtures, however its incorporation in top asphalt pavement layers is still very limited (10e30%). In fact, despite the advan- tages that its use implies, RA content in road pavement surface courses is still restricted in most countries due to mainly legislation limitations, but also some technical issues. This paper aims at being a step further to improve the latter by providing a methodology that allows producing fundamental inputs for confidently performing mix design of asphalt mixtures incorporating up to 100% RA. The methodology consists in an advanced preliminary binder's blend design that can be used with a…
Effect of climate change on asphalt binder selection for road construction in Italy
2015
This work explores the influence of climate changes on the proper selection of asphalt binder for pavement construction purposes, according to the Performance Grade (PG) defined in the SUPERPAVE specifications. Based on temperature data at national level, it is possible to obtain thematic maps for the whole Italian territory, which is extremely useful for technicians and pavement engineers for selection of asphalt binder for road construction purposes. Furthermore, the statistical significant temperature trends’ knowledge enables deriving thematic maps which allows to include the effects of climate change in the asphalt binder design. It is argued that, due to climate change, the binders to…
Exploring the uncertainty in capacity estimation at roundabouts
2017
Abstract Purpose In gap-acceptance theory the critical and the follow-up headways have a significant role in determining roundabout entry capacities which in turn depend on circulating flow rates under a specified arrival headway distribution. Calculation considers single mean values of the gap-acceptance parameters, neglecting the inherent variations in these random variables and providing a single value of entry capacity. The purpose of this paper is to derive the entry capacity distribution which accounts for the variations of the contributing (random) variables and suggest how to consider this issue in the operational analysis of the roundabouts. Methods We performed a Monte Carlo simul…
Hybrid Procedure for Automated Detection of Cracking with 3D Pavement Data
2016
Pavement cracks are considered a major indicator of pavement performance. Because traditional manual crack surveys are dangerous, time consuming, and expensive, technologies have been developed to collect high-speed pavement images, and numerous algorithms have been proposed to detect cracks on pavement surface. The latest PaveVision3D Ultra system (3D Ultra) has been implemented to achieve 30-kHz three-dimensional (3D) scanning rate for 1-mm resolution pavement surface data at highway speed up to 100 km/h (60 mi/h). This paper presents the application of a hybrid procedure for automated crack detection on 3D pavement data collected using 3D Ultra. The procedure combines three different me…
Speed Stochastic Processes and Freeway Reliability Estimation: Evidence from the A22 Freeway, Italy
2013
In this paper, a criterion for predicting the reliability of freeway traffic flow is presented. The idea is based on an analysis of spot speed time series divided into sequences of events of random and homogeneous traffic processes. For each process, the flow rate and density were calculated; then the relationships between parameters of spot speed processes and vehicular density were obtained. Using these relationships and a simulation procedure for the spot speed process, a formulation for predicting the reliability of traffic flow moving along the offside lane on the freeway roadway was derived. Through this formulation and the measurements of flow rate and speed, the probability of insta…
Definition of a laboratory optimization protocol for road bitumen improved with recycled tire rubber
2012
Abstract Bearing in mind the need to answer one of the most frequent needs for civil construction, in general, and major project such as road infrastructures in particular, this paper presents the results of a laboratory experimental study in order to evaluate the performance improvement that is possible to achieve when modifying road bitumen with CRM (Crumb Rubber Modifier) from discarded tire rubber (TR), using a Wet Process. The environmental advantage is double, since the aim of the research is to obtain high performance road bitumen thanks to the re-use of a discarded material, such as the rubber tires, which otherwise would be dumped in scrap-yard. In particular, this experimental stu…
Turbo-roundabouts vs Roundabouts Performance Level
2012
AbstractIn this paper the performance level of basic turbo-roundabouts and double-lane roundabouts are compared. Cowan's M3 headway distribution was chosen to take into account bunched vehicles moving along each circulating lane; the Hagring model was adopted to evaluate entry capacity both at turbo-roundabout and at double-lane roundabout.The comparative analysis was performed evaluating operational performances in terms of delay suffered by users entering the intersection.Results of the analyses show that efficiency of basic turbo-roundabouts highly depend on traffic situations and can be significant when major road captures most of the traffic demand.
Environmentally appraising different pavement and construction scenarios: A comparative analysis for a typical local road
2015
Abstract The aim of this work is to carry out a comparative analysis of environmental impacts for different scenarios of a typical local road. Life Cycle Assessment (LCA) is the modeling tool used to quantify and characterize comparative environmental impacts. In carrying out this specific application of the LCA, different road construction techniques were considered with regards to the whole structure and compared in order to identify the best alternative in terms of environmental sustainability. So far, in fact, typical LCA frameworks of roads have focused on recycled materials for pavement layers only, thus neglecting study of the materials used in the embankment or in the subgrade. In t…
Tramway Track: A New Approach for Measuring the Transverse Profile of Worn-Out Rails
2012
Abstract Monitoring the wear condition of the tramway superstructure is one of the key points to guarantee an adequate safety level of the light rail transport system. The purpose of this paper is to suggest a new non-conventionalprocedure for measuring the transverse profile of rails in operation by means of image-processing technique. This methodological approach is based on the “information” contained in high-resolution photographic images of tracks and on specific algorithms which allow to obtain the exact geometric profile of the rails and therefore to measure the state of the rail-head extrados wear.