1,721,327 research outputs found
Maintenance and repair of airfield apron rigid pavements
No full textafter about 20 years in service, large sections of the concrete apron at Bari Civil Airport
(Italy) shows evident structural problems. Slabs are principally affected by structural cracks
and by shallow and deep spallings at joints. Present and forecast traffic data were collected and
compared with the bearing capacity of the pavement as well as with typologies and positions of distresses.
In particular it has been assessed that construction joints fatigue life has nearly expired.
According to the results of field investigations, the effectiveness of current repair methods was investigated
and original repair methods were developed both for spalled and cracked slabs. They
concern the partial reconstruction of slabs with a double layer of a new fibro–reinforced concrete.
Some trial repairs were carried out. After one year they showed no structural problems. So repairs
are now in progress on the main apron of Bari Civil Airport using these construction methods
Functional optimisation of porous pavements and porous fiction courses
No full textThe Polytechnic University of Bari is involved since some years in an
international research regarding the functional optimisation of porous friction
courses and porous pavements in general. After years of research, a design method
was developed concerning the water draining capacity of such pavements so to
decrease accident risks while driving in wet conditions. Currently, the research is
focused in the optimisation of the fuctional properties of such pavements as regard
the enviromental aspects. This is in collaboration with the University of Florida at
Gainesville , the ANAS Spa (Apulia Department) and Bari Municipality. A test site
was built on a ANAS road in th District of Foggia (I) and another one is being built
up in Bari. This research has also a branch regarding material that is carried in
collaboration with the Technical University of Warsaw
Relationships among gradation curve, clogging resistance, and pore-based indices of porous asphalt mixes
No full textWhen properly designed, porous asphalt functions both to make safer the driving in wet condition, and to provide hydrologic restoration while functioning as a filtration interface. This study examined the role of aggregate ranulometry both on the pore-based indices of porous asphalt and on the clogging resistance. Three groups of porous asphalt gradations comprised of 12 series of samples and separated based on gradation size indices have been examined. For all samples the vertical (kv) and horizontal (kh) permeability were measured with the commensurate total void contents (e) and total porosity (n). Also clogging resistance was evaluated by measuring hydraulic conductivity before and after 1 year of exposure of the samples to dust intrusion. Marshall tests were also performed in order to control the stability of the mixes. There was a strong relationship between the permeability and the void content. For a given aggregate gradation, each increment of asphalt content increase caused a decrement in permeability and porosity. As for the clogging resistance potential, it seems to be more related to the initial permeability than to the other pore-based parameters. Results indicated that in addition to the coefficient of uniformity (U) and the total void content, a size-based granulometric index (P5·P2·Dmax) provided a relationship with vertical permeability and the total void content that were very consistent for the entire range of porous asphalt mixes. Results of this study allow the role of mix design on the permeability to be examined. These mix design results are a necessary precursor to examination of in-situ
permeability after placement, and degradation of such permeability as a function of time and rainfall-runoff hydraulic and particulate loading
Connecting Rural Road Design to Automated Vehicles: The Concept of Safe Speed to Overcome Human Errors
No full textThe human-road-vehicle automated system is a challenge to overcome human errors. Several rural road crashes happen due to loss of friction, unlikely predictable by drivers. The friction diagram method (FDM) by the authors, described in previous papers, is able to evaluate the skidding risk taking into account vehicle, environmental, road factors. An important variable is the vehicle speed. According to the FDM, the speed corresponding to the maximum friction used can be computed. If all vehicles will travel at speeds lower than that, all other safety checks being verified, then the skidding risk can be reduced. Automated vehicles could travel at the safe speed predicted for each section, by acquiring all the necessary information directly from the road. The algorithm can be customized according to the particular vehicle, tires and road conditions. Additional remarks about the shift from traditional road design practice to the driving automation are also given
Integrated American-European protocol for safety interventions on existing two-lane rural roads
Full text linkThe main purpose was to integrate two strategies for road safety analyses (qualitative: audits, inspections; and quantitative: accident predictions) and develop a possible protocol for the safety interventions on existing two-lane rural road segments. Those road sections do not typically belong to the TEN-network, to which the 2008/96/EC Directive is mainly oriented. Hence, they could lack of methods for designing safety-based interventions. The main research questions were: Which possible problems can arise from the application of this protocol to real cases? Which data are practically needed? Which possible solutions can be provided for the highlighted problems? The integrated protocol, including: 1) the HSM predictive method, 2) the EU Regulations, 3) the local road design standards, 4) some research developments; is applied to real two-lane rural road segments requiring safety-based interventions. Its application is divided in the typical road safety analysis stages. A wide list of possible problems was highlighted and addressed: 1) lack of data, 2) difficult comparison with current road standards in order to identify safety problems, 3) lack of methods for evaluating the skidding risk along the layout, 4) setting speed limits, 5) need for optimizing the selection of countermeasures based on their aims and their timely application, in different recurrent situations, 6) availability and comparison of predictive methods. Based on the problems and solutions discussed, main advantages (1) the systematic approach, 2) the quantitative assessment of benefits, 3) the possible transferability) and disadvantages (difficulties in overcoming the lack of data and calibrated accident prediction models) of the method were remarked
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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