Evaluation methods for improving surface geometry of concrete floors. A case study

Among various construction activities, related to concrete pavement technologies, an important role is reserved to industrial floors. For these structures it is necessary to ensure resistance and stability, durability, reliability and many other properties. In particular, the flatness is a special requirement that assumes a real significance respect to functional performances, especially when the pavement has to allow the movement of vehicles and goods or the storage in elevated stacks or shelves. The flatness can be defined in different ways, but in every cases it is referred to pavement surface geometry, that has to be even (without superelevated or depressed areas) and level (horizontal, without grades, curvatures and waves). The acceptance limits are defined by technical standards, in various Countries, together with the suitable methods for measurements and controls. In many cases, however, these methods are considered not really feasible or easy, in particular when a continuous sampling of the pavement, along selected alignments, is needed. In particular, the paper describes the operating procedures to calculate indexes FF and FL, according to ASTM 1155M standard, starting from data provided by a contact profilometer. If the target values are not reach, it is necessary to provide some alternative solutions to avoid the demolition of the slabs or the payment of penalties by the builder, if this is required by the contract. There are two main possible methods for increasing flatness and levelness while other functional surface properties are maintained at the expected levels: the surface grinding and the overlapping with self-levelling and high resistance resins. A case study where the two alternative methods are applied to improve flatness and levelness of a surface is presented. The results of measures made before and after the treatments showed that both the solutions are able to ensure, within certain limits, the fulfillment of the requirements and consequently they can be used for the proposed aims

The public safety zones around small and medium airports

Proper planning around airports safeguards the surrounding territory from risks of air accidents. Many countries have defined Public Safety Zones (PSZs) beyond the runway thresholds as a result of targeted risk assessment methods. Therefore, national aviation Authorities could limit building construction and industrial development in order to contain the risk for dwellers to be involved in aircraft accidents. The number of people who live, work or congregate in these areas should be limited. The procedure to set Public Safety Zones is based on advanced technical analyses for major infrastructures. For smaller airports, simplified schemes are used, but, sometimes, they are not as effective when considering the actual safety conditions. This article aims to identify the shape and size of the Public Safety Zones for small and medium one-runway airports. The influence of the volume and mix of traffic on the PSZ geometry has been evaluated using the program named SARA (Sapienza Airport Risk Analysis); the results are correlated with the current Risk Plans generally adopted in Italy. According to the air traffic, the Risk Plans are characterized by a dynamic definition and fit the results obtained from risk assessment

Prioritization methodology for roadside and guardrail improvement: Quantitative calculation of safety level and optimization of resources allocation

The attention to road safety-related issues has grown fast in recent decades. The experience gained with these themes reveals the importance of considering these aspects in the resource allocation process for roadside and guardrail improvement, which is a complex process often involves conflicting objectives. This work consists on defining an innovative methodology, with the objective of calculating and analysing a numerical risk factor of a road. The method considers geometry, accident rate, traffic of the examined road and four categories of elements/defects where the resources can be allocated to improve the road safety (safety barriers, discrete obstacles, continuous obstacles, and water drainage). The analysis allows the assessment of the hazard index, which could be used in decision-making processes. A case study is presented to analyse roadsides of a 995 km long road network, using the cost-benefit analysis, and to prioritize possible rehabilitation work. The results highlighted that it is suitable to intervene on roads belonging to higher classes of risk, where it is possible to maximize the benefit in terms of safety as consequence of rehabilitation works (i.e., new barrier installation, removal and new barrier installation, and new terminal installation). The proposed method is quantitative; therefore, it avoids providing weak and far from reliable results; moreover, it guarantees a broad vision for the problem, giving a useful tool for road management body

Comparative life cycle assessment of lighting systems and road pavements in an Italian twin- tube road tunnel

This work calculates and discusses the Life Cycle Assessment (LCA) of four scenarios composed of two types of road pavements and two types of lighting systems to be built in an Italian twin-tube road tunnel. A 20-year time horizon is adopted to assess the burdens of construction and maintenance of both flexible and rigid pavements and high-pressure sodium (HPS) and lightemitting diode (LED) lamps, traffic, and switching on of lamps. All considered scenarios are comparable with each other in terms of technical performances, but significantly differ regarding their environmental consequences. The geometrical and technical characteristics of the examined scenarios comply with current Italian standards for highways. In all the examined cases, LCA is carried out according to the European standard, EN 15804, and includes 19 impact categories (IC). The analysis demonstrates that the use of more reflecting surface pavement materials (i.e., concrete vs. asphalt) and more performing lighting systems (i.e., LED vs. HPS) can effectively mitigate the deleterious burdens related to road construction, maintenance, and use. For most of the examined ICs, the most environment-friendly scenario has LED lamps and concrete pavement

New research opportunities for roadside safety barriers improvement

Among the major topics regarding the protection of roads, restraint systems still represent a big opportunity in order to increase safety performances. When accidents happen, in fact, the infrastructure can substantially contribute to the reduction of consequences if its marginal spaces are well designed and/or effective restraint systems are installed there. Nevertheless, basic concepts and technology of road safety barriers have not significantly changed for the last two decades. The paper proposes a new approach to the study aimed to define possible enhancements of restraint safety systems performances, by using new materials and defining innovative design principles. In particular, roadside systems can be developed with regard to vehicle-barrier interaction, vehicle-oriented design (included low-mass and extremely low-mass vehicles), traffic suitability, user protection, working width reduction. In addition, thanks to sensors embedded into the barriers, it is also expected to deal with new challenges related to the guidance of automatic vehicles and I2V communication

Airport veer-off risk assessment: An italian case study

The objective of this paper is to assess the veer-off risk of an Italian airport that is characterized for having near 12,000 annual movements. The name of this airport is not disclosed for security purposes. The methodology used followed the principles of probabilistic risk analysis in order to characterize the events and assess the corresponding damages. The study used statistical data about accident reports and local conditions that were collected following the standards of the International Civil Aviation Organization (ICAO). The methodology used in this work complies with the guidelines for the adjustment of lateral runway strips, edited by the Italian Civil Aviation Authority (ENAC). Besides, data available in worldwide databases of airplane accidents were also gathered and included as part of the analysis. The method used to assess the veer-off risk of the airport is consistent with probability and damage quantification methods published in the literature. The main variables considered in the analysis were traffic information, wind conditions, the existence of landsidebuildings adjacent to the runway, and the geotechnical conditions of the subgrade underneath the strip zones. For the assessment of the veer-off risk, the authors used primary data provided by the airport management body within the period 2013-2015 and secondary data available in the literature. The risk of veer-off was calculated in more than 1,500 points around the runway. Besides, the authors proposed maximum allowable risks in different locations, and these values were compared to the actual risk levels previously computed. The results of this comparison suggested that improvements in the soil capacity and/or in the airport management activities might contribute to achieve the proposed allowable risk. The results from this assessment showed that the two critical variables determining the risk of veer-off accidents in the airport under evaluation were wind conditions and the bearing capacity of the soil underneath the strip areas. Also, it was found that the highest veer-off risk level obtained within the Cleared and Graded Area (CGA, part of the runway strip cleared of all obstacles and graded) was 2 10-7, while the lowest level was 3 10-8, which are considered typical risk ranges in airport operations. In general, the results demonstrate that the adopted methodology is a useful tool to evaluate the veer-off risk of a specific airport. Besides, the method allows comparing the actual levels of risk with proposed target levels of safety.Consequently, the quantification of the veer-off risk levels offers the airport management body the possibility of implementing appropriate measurements in those cases where minimum safety requirements are not achieved

Safety problems in urban cycling mobility. A quantitative risk analysis at urban intersections

The attention to the most vulnerable road users has grown rapidly in recent decades. The experience gained reveals an important number of cyclist fatalities due to road crashes; most of which occur at intersections. In this study, dispersion of trajectories in urban intersections has been considered to identify the whole conflict area and the largest conflict areas between cars and bicycles, and the speeds have been used to calculate exposure time of cyclists and reaction time available to drivers to avoid collision. These data allow the summary approach to the problem, while a risk probability model has been developed to adopt an elementary approach analysis. A quantitative damage model has been proposed to classify each conflict point, and a probabilistic approach has been defined to consider the traffic volume and the elementary unit of exposure. The combination of damage and probability, permitted to assess the risk of crash, at the examined intersection. Three types of urban four-arm intersection, with and without bike paths, were considered. For each scheme, the authors assessed the risk of collision between the cyclist and the vehicle. The obtained results allowed the identification of the most hazardous maneuvers and highlighted that geometry and kinematics of traffic movements cannot be overlooked, when designing an urban road intersection. The strategy proposed by the authors could have a significant impact on the risk management of urban intersections. The obtained results and the proposed hazard estimation methodology could be used to design safer intersections

Development of a HGV FEM for road safety analysis

In the last years roadside safety design, in particular for passive systems, was greatly improved with the possibility to use computational mechanics. Computational mechanics is based on the use of complex finite element codes, that allows the virtual reproduction of real world problems. Regarding roadside safety, the design phase was, until now, based on the use of simplified analysis, unable to describe accurately the complexity of vehicle impacts against safety hardware. To build a FE model for an impact problem many elements are necessary: • Model geometry. • Constitutive laws of the materials. • Links (rigid, cinematic, etc.) between bodies or part of them. • Definition and characterization of contact surfaces. This set of information is needed for each different body involved in the event; making the development of a complete model very much demanding, but once a part (subset) of the entire model has been accurately validated by the comparison with real experimental data, it can be used again and again in other analogous models. Our goal was to build and validate a FE model of a Heavy Goods Vehicle (HGV). We chose this kind of vehicle because it wasn't available and because it was useful to test the containment of the barriers, and to study the dynamic interactions between vehicle and road pavement. In particular, this vehicle can be used to test the safety barriers according to EN 1317 standard, for the H4a class of containment. It reproduces a FIAT-IVECO F180 truck, a vehicle with 4 axles and a mass of 10.5 ton (30 with the full load). The model (12337 elements and 11470 nodes) was built for and is ready to use with LS Dyna FE code from Livermore Software Technology Corporation

Procedure for the Identification of Existing Roads Alignment from Georeferenced Points Database

The aim of this research is to look for an automated, economical and fast method able to identify the elements of an existing road layout, whose original geometric design could date back to distant ages and could have undergone major modifications over the years. The analysis has been directed towards the Italian two-lane rural roads; the national public company ANAS made available its graph, obtained from high-performance surveys, that represents about 90% of these roads’ network. The graph is made up of a collection of georeferenced points but does not recognize or describe the geometric elements making up the roadway. Consequently, it has been necessary to design and develop an original procedure, subsequently implemented in a programming platform, able to identify the characteristics of the several parts, which constitute the reference axes of the existing roads. This research focuses on the horizontal geometry assessing the coherence, consistency and homogeneity of the roads’ layout, through the ex post application of the regulatory model for the design verification. If road sections are identified in which some conditions are not significantly met, further investigation should be conducted in order to ensure road safety and to plan any road upgrading activities

Operating times and users' behavior at urban road intersections

The safety of at grade road intersections is a relevant issue with social, economic, and environmental implications. It is related to the behavior of a driver approaching an intersection that, in its turn, is affected by kinematic and physiological variables. This study proposes a model to calculate the intersection operation time (IOT) for typical non-signalized 4-leg and 3-leg (or T-leg) urban intersections. Data available in the literature have been considered in order to identify the points of interest and assess the number and the time of a driver's eye fixation on them. When approaching an intersection, the probability of glancing in a particular area changes with the distance to the yield or stop line; for this reason, a probabilistic approach was used to model the phenomenon. All possible maneuvers have been considered: left turning, right turning, and through-movement. The proposed model allowed an objective comparison between time spent by drivers for various maneuvers and layout conditions, and identification of the critical conditions. Indeed, significant differences in terms of IOT were found: they could lead to modification of the traffic management considering different needs of road users, traffic demand, and geometrical and functional constraints