Durabilitatea este un termen folosit tot mai des în ultima vreme, acesta bazându-se pe trei tipuri de factori: sociali, economici și de mediu. Sistemele durabile de transport duc la creșterea coeziunii sociale, reduc problemele de mediu și ajută la crearea unei economii mai eficiente. Transportul durabil constă într-un sistem complex, care este proiectat pentru a asigura nevoile de mobilitate ale generațiilor prezente, fără a deteriora factorii de mediu și de sănătate. Prin îmbunătățirea eficienței energetice și reducerea consumului de materiale, acesta trebuie să fie capabil să îndeplinească în condiții optime, nevoia de mobilitate pentru generațiile viitoare. Sistemul de transport actual din țara noastră nu are un caracter de durabilitate.
Acest articol încearcă să identifice o serie de probleme și disfuncționalități ale sistemelor de transport, din perspectiva unui sistem de transport durabil. Pentru alinierea la standardele Uniunii Europene este necesar să se ia măsuri pentru îmbunătățirea actualului sistem de transport.
Soluțiile propuse trebuie să fie soluții ecologice, social și economic viabil echitabile. Există o serie de beneficii prin implementarea unui astfel de sistem, atât directe, cât și indirecte: un cost redus de transport, confort sporit, mai puțină poluare a mediului, reducerea accidentelor rutiere. Durabilitatea rețelelor de drumuri este atât o provocare cât și o necesitate a zilelor noastre.
The benefits of WMA technologies include reduced fuel usage and emissions in support of sustainable development, improved field compaction, which can facilitate longer haul distances and cool weather pavement, and better working conditions. Since this is a relatively new technology, it is necessary to determine the behavior and the performances of this type of asphalt mixture depending on additive percent.
These technologies tend to reduce the viscosity of the asphalt and provide for the complete coating of aggregates at lower temperatures. WMA is produced at temperatures 20 to 30°C lower than typical hot-mix asphalt (HMA).
The paper presents the results obtained in the Road Laboratory of Technical University of Civil Engineering Bucharest on an asphalt mixture with fibers (MASF16) prepared according to the “warm mix” technology with chemical additive. Different percent of additive are used in laboratory to draw up the “master curves” of asphalt mixture obtained by 4PB-PR stiffness modulus results.
Saša Ahac, Ivo Haladin, Stjepan Lakušić and Vesna Dragčević
The paper gives an overview of concrete noise barrier application in several EU countries and in Croatia. It describes a process of introducing different noise protection solutions on Croatian market in the phase of intensive motorway construction in recent years. Namely, an extensive motorway network has been constructed in Croatia in the last 10 years. Following the process of motorway construction, noise protection walls have also been erected. Usage of different building materials and installation processes as well as variations in building expenditures has led to a comparative analysis of several types of noise protection solutions (expanded clay, wood fibre) including a new eco-innovative product RUCONBAR, which incorporates rubber granules from recycled waste tyres to form a porous noise absorptive layer.
Road bridges with steel arches are used efficiently for medium and large spans. These solutions show advantages determined by the arches geometry, by the number and distributions of hangers and by the form and type of the arches bracing system.
The appearance of the welding as standard connection procedure for steel bridges, for road bridge decks two solutions are mainly used:
- the solution with a concrete slab acting together with the stringers and cross beams (the composite solution);
- the solution with orthotropic deck (the orthotropic deck consists in a network formed by the continuous longitudinal stiffeners and cross beams connected at the upper part by a steel plate).
In this paper a comparative study of the strength and fatigue checks performed on the new road bridge over river Argeşel near Mioveni in Argeş county is presented. The results are obtained using the Romanian standards STAS 1844-75 and SR 1911-1998 and the European norms SR EN 1990, SR EN 1993 and SR EN 1994. The deck was designed with two parallel steel arches, which are sustaining through vertical hangers a concrete slab connected with steel girders at the way level.
The aim of the paper is to outcome the safety factors obtained from checks performed on steel hangers using the Romanian standards with respect with those obtained using Eurocodes.
Thessaloniki is the second largest city in Greece and its transportation system (development and operation) is hampered by the city’s geographical position and surrounding relief. Specifically, the city has been developed and expanded through the years along the coastline, the sea boundary on the southwest, and a second physical boundary, a forest, on the east side. The Thessaloniki Ring Road (divided in western and eastern part) was constructed in the early ‘90s, in order to relief the road network of the city centre from the transit traffic and confront the gradually increasing congestion. The absence of alternatives other than road transport and the increase of car ownership over the years led to an increase of motorized traffic. So even that this Ring Road had been designed to serve 30,000 vehicles daily it became to serve more than triple traffic just before the impacts of the economic crisis on transport and mobility have been made visible.
The Western Internal Ring Road of Thessaloniki (WIRRT) has length of 8.4km. It has three lanes per direction separated by a median and no emergency lanes. The traffic increase and moreover the existence of eight at grade intersections along the WIRRT degrade the provided level of service. For the elimination of these intersections an upgrade project is underway for implementation that includes the construction of five grade separated intersections and several interventions on the adjacent road network. This paper presents in brief the methodology and the results of the project’s Cost-Benefit Analysis, which assessed the expected socioeconomic benefits, emerging mainly from minimising the delays for users due to the elimination of the at grade signalised intersections.
The process of pavement maintenance and rehabilitation starts by collecting the data which will form the base for evaluation of pavement functional and structural condition. Collection of data can be performed by destructive and non-destructive testing. Usually preferred are the non-destructive methods, that do not damage the pavement, and the process of pavement evaluation is objective and repeatable. Non-destructive testing methods are becoming more and more popular, especially for assessing the structural condition of the pavement. Non-destructive testing by a Falling Weight Deflectometer (FWD) and the analysis of so collected data by the process of backcalculations is today the usual tool for assessing pavement bearing capacity. One of the basic input parameters for analysis of the data collected by FWD is pavement layers thickness.
The practice in Croatia is to determine pavement layers thickness by coring. This destructive method affects pavement integrity, so the number of such tests should be kept to the minimum. By coring the accurate thickness of all pavement layers is obtained on specific point locations. Thus, numerous deviations in layer thickness remain unnoticed, and in the end, use of such data for the process of backcalculations does not provide ac urate values of layer moduli. Coring can be replaced with non-destructive method of testing by Ground Penetrating Radar (GPR), which provides continuous information on thickness of all pavement layers.
The paper shows the method for assessing the bearing capacity of the pavement based on the data collected by FWD, GPR and coring. The calculation for layer moduli was performed by the ELMOD software, separately for the layers thickness data obtained by coring, and separately for the thickness obtained by GPR tests. Analysis and comparison of the results of calculated elasticity moduli obtained by using various methods for collecting layer thickness data were performed in the paper.
Aldo Giordano, Giorgio Pedrazzi and Giovanni Voiro
This paper describes the design and construction of a “balanced cantilever girder” bridge over the Danube-Black Sea channel, characterized by a central span of 155m with two symmetrical side spans of 77.5m. The total length of the bridge, including portions of the abutments support, is 312.0m.
The bridge main features, from calculation as well as construction points of view, are in particular the post-tensioning tendons, distributed both a top and bottom sides of the section along the bridge. The former ones play a key role in the construction phase, for the need of counterbalancing selfweight while subsequent segments are realized.
Tendons are symmetrical about midspan, with anchors positioned at the end of each segment.
Bridge deck is supported by two piers outfitted with friction pendulum seismic bearings, which develop friction both in static conditions to withstand static forces and small displacements, and in dynamic conditions, causing dissipation. Under severe earthquake load all structures (deck and piers) develop only elastic behavior.
This papers presents a detailed review of the design process as well as a time journey during construction
Goran Kos, Predrag Brlek, Kristijan Meic and Kresimir Vidovic
In terms of continual increase of number of traffic accidents and alarming trend of increasing number of traffic accidents with catastrophic consequences for human life and health, it is necessary to actively research and develop methods to combat these trends. One of the measures is the implementation of advanced information systems in existing traffic environment. Accidents clusters, as databases of traffic accidents, introduce a new dimension in traffic systems in the form of experience, providing information on current accidents and the ones that have previously occurred in a given period. This paper proposes a new approach to predictive management of traffic processes, based on the collection of data in real time and is based on accidents clusters. The modern traffic information services collects road traffic status data from a wide variety of traffic sensing systems using modern ICT technologies, creating the most accurate road traffic situation awareness achieved so far. Road traffic situation awareness enhanced by accident clusters' data can be visualized and distributed in various ways (including the forms of dynamic heat maps) and on various information platforms, suiting the requirements of the end-users. Accent is placed on their significant features that are based on additional knowledge about existing traffic processes and distribution of important traffic information in order to prevent and reduce traffic accidents.
Ensuring sufficient visibility on planned roads by sight distance testing is an integral part of every project, but problems with visibility can emerge when noise barriers are erected on existing roads. Namely, in order to provide sufficient noise protection, high noise barriers are often placed at minimum distance from the carriageway edge, and additional visibility testing in most cases is not carried out.
Research described in this paper consists of stopping sight distance tests conducted by means of specialized road design software MX Road, and noise barrier optimization conducted by means of specialized noise prediction software LimA using static noise calculation method RLS 90. The aim of this research is to establish whether the required stopping sight distance on road sections where minimum design parameters are applied can be achieved if the noise barrier is placed at minimum distance from the carriageway edge, and to establish whether the optimized dimensions of planned noise protection barrier will change if the barrier is placed on larger distance from the noise source, which is, in this case, the existing road.
Lucrarea abordează comportarea unui model de solid-rigid cu anumite simetrii structurale. Aceste simetrii permit simplificarea calculelor (ecuaţii de mişcare) şi, deci, a modelelor matematice. Dacă solidul rigid este conectat la structură prin patru legături elastice, modelul rămâne încă simplu şi uşor de rezolvat, vibraţiile putând fi decuplate în patru subsisteme de mişcare.
În final, se prezintă un studiu de caz pentru analiza modală a unui viaduct, modelat precum un corp solid-rigid, rezemat elastic, de pe autostrada Transilvania (km 29+602.75 m).