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Abstract

Starting from consideration that urban intersections are sites with promise for safety and operational improvements, the paper describes the steps taken to develop a crash predictive model for estimating the safety performance of urban unsignalized intersections located in Palermo, Italy. The focus is on unsignalized four-legged one-way intersections widespread in Italian downtowns. The sample considered in the study consist of 92 intersections in Palermo, Italy. For the study were collected crashes occurred in the sites during the years 2006‒2012, geometric design and functional characteristics and traffic flow. Results showed that data were overdispersed and NB1 distributed. In order to account for the correlation within responses Generalized Estimating Equations (GEE) were used under different working correlation matrices.
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Abstract

In the paper, a choice criterion between flower roundabouts and double-lane roundabouts is proposed, focusing on operational benefits that can derive from one scheme over the other, and outlining a general framework for benefit-cost analysis. In order to assess operational benefits of innovative roundabouts over modern roundabouts, a comparative analysis was made. Capacity was estimated using gap-acceptance models. In detail, assuming the dichotomic shifted negative exponential distribution to model headways in circulating streams, the Hagring formula was adjusted to obtain entry capacity estimations at roundabout approaches where entering vehicles face one or two conflicting flows. Based on the control delay, the suitability domains and indifference areas were constructed. Thus, a sensitivity analysis to changes in traffic demand for operational benefits of flower roundabouts over double-lane roundabouts was carried out and discussed. At last, evidence for new installations and conversion of existing roundabouts can be found.
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Abstract

Micropaleontological and palynological samples from three Cenozoic diamictites at Cape Lamb, Vega Island, James Ross Basin were analysed. Fossiliferous samples yielded reworked and autochthonous a ssemblages of Mesozoic calcareous nannofossils, impoverished Cretaceous foraminifer a together with Neogene species, as well as Late Cretaceous dinoflagellate cysts, pollen, spores and abundant Cenozoic microforaminiferal linings. The recovered nannoflora indicates Early Cretaceous (Hauterivian–Albian) and Late Cretaceous (Santonian–Early Campanian) ages, suggesting an in tensive reworking of marine sediments. The presence of the Early Cretaceous species Nannoconus circularis Deres et Acheriteguy in the diamictite represents its first record for the James Ross Basin. The scarce foraminiferal fauna includes Pullenia jarvisi Cushman, which indicates reworking from lower Maastrichtian–lower Paleocene sediments, and also the Neogene autochthonous Trochammina sp. aff. T. intermedia. The inner−organic layer observed inside this specimen appears to be identical to microforaminiferal linings recovered from the same sample. Palynomorphs found in the studied samples suggest erosion from the underlying Snow Hill Island and the López de Berto − dano Formation beds (upper Campanian–upper M aastrichtian). These recovered assemblages indicate either different periods of deposition or reworking from diverse sources during Cenozoic glaciation, originating in James Ross Island and the Antarctic Peninsula with the influence of local sediment sources.
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