Turbo roundabouts: geometric design parameters and performance analysis

A turbo roundabout is a particular type of roundabout where entering and circulating lanes are bounded by traffic signs and by non-mountable curbs. The physical separation between lanes, both at entries and on the ring, helps to prevent side collisions crossing the roundabout.The main advantages of turbo roundabouts are: i) reduction in the number of potential conflict points; ii) lower speed of vehicles passing through the intersection; iii) safety conditions at the intersection due to lower risk of side-by-side accidents. Also, in some cases the capacities of turbo roundabouts are higher than the capacities of conventional roundabouts.This paper presents an estimation of capacity, delays and level of service of turbo roundabouts in undersaturation conditions, considering both vehicular flow and pedestrian stream. It also examines the geometric parameters of the central island and circulating lanes in several turbo roundabout layouts

A LOGIC FUZZY MODEL FOR EVALUATION OF THE RAILWAY STATION'S PRACTICE CAPACITY IN SAFETY OPERATING CONDITIONS

Abstract The practice capacity of a railway junction depends, in addition to the effective operation's conditions, by the potential risk factors related to the design plan of the railway station. With the aim of an approach based on the "fuzzy sets" it is possible to determine the numeric value of the practice capacity by the logic - qualitative relations between the features of the railway junction and the potential risk factors. This methodology permits to try out the absolute value of a suitable vector β, (less then the unit) for the utilization of the theoretic capacity in conditions of maximum reliability of the system related to the aspect of safety (technique "fail safe")

Left subclavian artery coverage during thoracic endovascular aortic repair and risk of perioperative stroke or death

IntroductionLeft subclavian artery (LSA) coverage during thoracic endovascular aortic repair (TEVAR) is often necessary due to anatomic factors and is performed in to up to 40% of procedures. Despite the frequency of LSA coverage during TEVAR, reported associations with risk of periprocedural stroke or death are inconsistent in reported literature. We examined the 2005-2008 American College of Surgeons National Surgical Quality Improvement Program Participant Use Data file to determine associations between LSA coverage during TEVAR and risk of perioperative stroke or death.MethodsCurrent procedural terminology (CPT) codes were used to identify patients undergoing TEVAR, LSA coverage, and subclavian revascularization. Patients undergoing coronary bypass, ascending aortic repair, abdominal aortic aneurysm repair, or nonvascular intra-abdominal procedures during the same operation were excluded. Perioperative stroke and mortality associations with LSA coverage were examined using logistic regression models for each outcome. Significance was assessed at α = 0.05, with univariable P < .05 required for multivariable model entry.ResultsEight hundred forty-five TEVAR procedures were identified, of which 52 patients were excluded due to additional major procedures performed with TEVAR. Seven hundred thirty-three of the remaining 793 procedures included CPT codes indicating primary placement of an initial thoracic endograft and form the basis of this analysis. LSA coverage occurred in 279 procedures (38%). Thirty-day stroke and mortality rates were 5.7% and 7.0%, respectively. LSA coverage was associated with increased 30-day risk of stroke in multivariable modeling (odds ratio [OR], 2.17 95% confidence interval [CI], 1.13-4.14; P = .019). Other significant multivariable risk factors for stroke included proximal aortic cuff placement during TEVAR (OR, 2.58; 95% CI, 1.30-5.16; P = .007) and emergency procedure status (OR, 3.60; 95% CI, 1.87-6.94; P < .001). No significant association between LSA coverage and perioperative mortality was identified (univariable OR, 1.70; 95% CI, 0.98-2.93; P = .0578).ConclusionLSA coverage during thoracic endovascular repair is associated with increased risk of perioperative stroke following TEVAR. Further evidence is needed to determine whether procedural modifications, including LSA revascularization, reduce the incidence of stroke associated with TEVAR

Characterization of resident surgeon participation during carotid endarterectomy and impact on perioperative outcomes

IntroductionThe impact of resident surgeon participation during vascular procedures on postoperative outcomes is incompletely understood. We characterized resident physician participation during carotid endarterectomy (CEA) procedures within the 2005-2009 American College of Surgeons National Surgical Quality Improvement Participant Use Datafile and evaluated associations with procedural characteristics and perioperative adverse events.MethodsCEAs were identified using primary current procedural terminology codes; those performed simultaneously with other major procedures or unknown resident participation status were excluded. Group-wise comparisons based on resident participation status were performed using χ2 or Fisher's exact test for categorical variables and t tests or nonparametric methods for continuous variables. Associations with perioperative adverse events (major = stroke, death, myocardial infarction, or cardiac arrest; minor = peripheral nerve injury, bleeding requiring transfusion, surgical site infection, or wound disruption) were assessed using multivariable logistic regression models adjusting for other known risk factors.ResultsA total of 25,280 CEA procedures were analyzed, of which residents participated in 13,705 (54.2%), while residents were absent in 11,575 (45.8%). Among CEAs with resident physician participation, resident level was categorized as junior (postgraduate year [PGY] 1-2) in 21.9%, senior (PGY 3-5) in 52.7%, and fellow (PGY ≥6) in 25.3%. Major adverse event rates with and without resident participation were 1.9% versus 2.1%, and minor adverse event rates with and without resident participation were 0.9% versus 1.0%, respectively. In multivariable models, resident physician participation was not associated with perioperative risk for major adverse events (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.75-1.08) or minor adverse events (OR, 0.93; 95% CI, 0.72-1.21).ConclusionsResident surgeon participation during CEA is not associated with risk of adverse perioperative events

A LOGISTICS PATTERN FOR FRUIT AND VEGETABLE TRANSPORTATION FROM ISLAND REGION: THE CASE OF SICILY

The globalization of markets regards many sectors in the E.U. and among them also the fruit and vegetable in the face of growing and increasingly intense competition exerted by the products of countries with emerging economies. But, at the same time, the globalization can also lead to the opening of new potential markets for the products, when and where the transport system, more than other things, appears to be efficient and effective and makes possible to reach the target markets in the shortest time possible and at the lowest possible cost. It is therefore very useful to create a model that takes into account hepeculiarities of the different modes of transport between the different origins/destinations and that allows a comparison in real-time, in terms of cost and time (eventually by the use of different ICT systems of easy access) for the evaluation of different alternatives of travel. These technologies, by romoting the grouping of goods, allow facilitating the formation of the load and, in the same way, of sorting the incoming as well as to make more efficient the total journey by helping to speed up the operations of embarking or of disembarking in the case of transportation combined "road-sea" type ro-ro. The proposed model, establishing an effective basis of information for trucks drivers, allows the development of alternative cheaper transports, before neglected because less rapid; as in the same time it may also allow to simulate the benefits of new actions on the supply of transport system (activation of new lines, reduction the time of boarding or of ferrying, etc.)

Calculation of turbo- roundabouts with slip lanes

A turbo roundabout is a particular type of roundabout where all lanes are bounded by traffic signs and by non-mountable curbs installed at entering and circulating lanes. Turbo roundabouts also have a very particular shape to accomplish the splitting of traffic streams and to prevent cars weaving through. These aspects make turbo-roundabouts more appropriate than roundabouts when a higher level of safety has to be guaranteed, particularly in presence of relevant pedestrian and two-wheels traffic volumes. Only in some traffic conditions, turbo roundabouts can offer higher capacities than conventional double-lanes roundabouts, so if more capacity must be guarantee a bypass lane can be added to the turbo roundabouts layout. This paper presents a closed-form model for the estimation of capacity, delays and level of service of turbo-roundabout equipped with Right-turn bypass lanes, considering the effect of geometric slip lane schemes, control type, vehicular and pedestrian flow

The design of waiting and storage areas to improve the efficiency of the marine intermodal terminals

The correct sizing of storage areas in the port areas is aimed to optimizing the management of intermodal transport and to ensure efficiency and functionality to the entire port system. In this paper is proposed a simulation model for design the port storage areas taking into account many parameters like: the service time, the randomness of the arrivals process, the storage capacity in terms of TEU that can be stored (and handled) in the unit of time. The capacity of the terminal warehouse is determined by the interrelation between fixed and static parameters in the short period which are: i) the extension of the storage area; ii) the height of the overlapping batteries of container (defined also like number of \u201cshooting\u201d); iii) the means of movements; iv) a series of parameters that can vary the efficiency degree according to the operativity conditions of the terminal. The optimal level of use is achieved when it is employed approximately the 60-65% of the maximum storage capacity; it is kept in account, therefore, a tolerance necessary in order to make forehead to eventual peaks of traffic