Analysis of Adaptive Traffic Control Systems Design of a Decision Support System for Better Choices

open3siNear half of the world population lives in cities. For many years big cities have faced the dif culties caused by junctions. Junctions and congestion are the cause of many other problems, like air pollution, time waste, delays, increased average trip time, decreased average cruise speed, increased fuel consumption and many others. These important issues cost a lot to governments in terms of both time and money. Cities suffer from the well-known problem of xed-time planning for traf c signals at intersections. In this paper the authors went through these problems and discussed about the dif culties of xed-time plan traf c lights and their solutions. Adaptive traf c control systems are one of the soltions which are exactly opposite to xed-time plans. Four different adaptive traf c control systems will be discussed. Each of them has unique characteristics that make it worthy to compare. The general architecture of these systems is based on a similar concept, but there is a great number of general and detailed differences that makes them interesting to compare. By making a deep comparison between these systems, which is one of the outputs of this research, governments and the authorities in charge can have an appropriate reference to look for their bene ts and choose an adaptive traf c control system to apply to their networks.Studer, Luca; Ketabdari, Misagh; Marchionni, GiovannaStuder, LUCA PASINO; Ketabdari, Misagh; Marchionni, Giovann

Assessing the Impact of Rutting Depth of Bituminous Airport Runway Pavements on Aircraft Landing Braking Distance during Intense Precipitation

A runway pavement during its useful life is subject to a series of deteriorations because of repeated load cycles and environmental conditions. One of the most common deteriorations is the formation of rutting (surface depression in the wheel path) on the runway surface. Rutting negatively affects aircraft performance during landings and will behave even worse during precipitation or with the existence of fluid contaminations on the surface. This paper aims to develop a model for calculating aircraft braking distance during landing on wet-pavement runways affected by rutting based on dynamic skid resistances generated by tire–fluid–pavement interactions. Intense precipitation, variable rutting depths for a 100 m length step, water film depths (e.g., 1 to 26 mm), and aircraft wheel loads (e.g., 10 to 140 kN) are considered as the boundary conditions of the developed model. The output is a model that can estimate aircraft braking distance as a function of rutting depth and can perform further assessment of the probability of the occurrence of landing overrun. After validating the model with existing methodologies and calibrating it according to the actual landing distance required for each type of aircraft, an Italian airport is simulated using a model with real data regarding the level of service of its pavement surface characteristics

Influence of Embedded Charging Units Characteristics on Long-Term Structural Behavior of E-Roads

The use of Electric Vehicles (EV) seems to be a promising solution to achieve a sustainable road transport system. Among the contactless dynamic vehicle charging technologies, the use of Charging Units (CUs)—cement concrete box—embedded into the road pavement seems to be a favorable option. The available scientific papers related to the structural effects of embedding CUs in road pavements consider the CU as a solid box, even if a cavity is needed for the electrical technologies’ accommodation. This is why the current research is aimed at studying electrified roads (e-road) with different CU cavity shapes and dimensions. In detail, pavement structural responses are investigated, as a first step, adopting a Finite Element Model (FEM), and, as a second step, the long-term performances (fatigue cracking/rutting proneness) are evaluated. The study is divided into two phases: the theoretical fatigue/rutting assessment, which allows to calculate the critical load repetitions leading to pavement failure, and an urban case study with the goals of both assessing the theoretical results and computing fatigue/rutting performance with real scale traffic conditions. The outcomes demonstrate that CUs can be used with no significant impacts on the long-term road pavement structural performance, laying the foundation for a future upgrading of the existing urban road networks

Effect of recycled concrete aggregate features on adhesion properties of asphalt mortar-aggregate interface

Asphalt-aggregate interface’s adhesion properties commonly affect the damage initiation and evolution within asphalt concrete materials, related to pavement durability and quality. The scope of this research was to investigate the influence of Recycled Concrete Aggregate (RCA) features on asphalt mortar-aggregate interface adhesion. Firstly, a three-dimensional reconstruction model of RCA was carried out using X-ray CT tomography and digital image processing. In this regard, five feature indicators, namely cement mortar content, sphericity, flat and elongated ratio, angularity, and surface texture, were proposed. Based on a bilinear cohesive zone model, the interface damage behavior of asphalt mortar-RCA was investigated by using a uniaxial compression simu- lation. Finally, a GA-BP artificial neural network was conducted to predict and quantify the effect of each feature indicator of RCA on interface adhesion. The results showed that when RCA had lower cement mortar content, higher sphericity value, and smoother surface, the asphalt mortar-RCA system was less prone to interface adhesion failure. The 5-14-1 GA-BP artificial neural network proposed in this study showed very good perfor- mance in predicting the interfacial dissipation damage energy with a mean-squared error value of 3.52 × 10^-4 for testing dataset. The cement mortar content parameter exhibited a remarkable influence on the interface adhesion property, and its global contribution to the interfacial dissipation damage energy (0.3486) was more than twice that of the surface texture parameter (0.1316). In future studies, the performance characteristics of cement mortar can be further investigated, thereby proposing RCA’s performance optimization technology

Assessing the impact of the slopes on runway drainage capacity based on wheel/path surface adhesion conditions

Aircraft braking distance is dependent on the friction between the main gear tires and runway pavement surface.Pavement texture, which is divided into macrotexture and micro-texture, has a noticeable effect upon friction, especially when the surface is wet. A risk analysis framework is developed to study the effects of longitudinal and transverse slopes on the aircraft braking distance in wet runway conditions and their influences on the probability of landing overrun accidents.This framework is operating under various water-film thicknesses, Maximum Landing Weights (MLW), and touchdown speed probability distributions for an acceptable range of longitudinal/transverse slopes and pavement texture depths.A simulator code is developed that initially computes the existing water-film thickness, as the result of intense precipitation,under aircraft main gear (depend on aircraft category) and then applies this variable as one of the main inputs to the aircraft braking distance computation. According to the obtained results, longitudinal gradient does not have a significant effect on the existing water depth on the surface although it affects the flow path length. Furthermore, 1% to 1.5% transverse slope causes rapid drainage of water from the runway surface and considerably decreases the probability of runway excursion accidents

Evaluating the interaction between engineered materials and aircraft tyres as arresting systems in landing overrun events

Abstract According to the registered databases of air accidents around the world, landing overruns are the most probable accidents among all runway excursion events. Although new aircraft are enhanced with the latest technologies that improve the maneuvers safety, the frequency of landing overruns are bound to increase because of the ascending growth rate of annual traffic. The principal scope of this paper is to evaluate the functionality of Engineered Materials Arresting System (EMAS) as a mitigation strategy to reduce the possible consequences of landing overrun events and in particular to determine if installing an EMAS can help land-locked airports to meet Federal Aviation Administration (FAA) recommendations in order to upgrade their Runway End Safety Areas (RESAs). In the previous studies, not enough investigations are dedicated to predicting the behavior of the aircraft and its deceleration rate after interfering EMAS and how different materials as arrestor beds would modify aircraft braking distance in RESA. Therefore, secondary objective of this paper is to determine the most optimum height of EMAS slabs, in function of execution costs and accident severity reduction rate. In this regard, a MATLAB®-based numerical code, which simulate the tire-pavement interface, is developed in order to evaluate the functionality of EMAS for aircraft ground maneuvers. Although this code is developed for both dry and wet runway conditions, dry runway's surface is selected as the boundary condition of this study. It simulates aircraft arresting distance by calculating a dynamic skid resistance between aircraft main gear and runway pavement with a fix time step. The results are plotted as risk contour intervals on the layout of EMAS that is installed at the RESA. In addition, this numerical code is adopted in order to perform a sensitivity analysis on five arresting bed materials, which consist of three low-density concretes with maximum crushing stress thresholds of 172500, 345000 and 930000 Pa, one gravel-based material and one foam aggregate-based mixture. Among all, low-density concrete with the highest crushing strength causes shorter aircraft arresting distance

Effect of crumb rubber and reclaimed asphalt pavement on viscoelastic property of asphalt mixture

Crumb rubber and reclaimed asphalt pavement have been widely used in the application of pavement engineering as they would greatly improve the high-temperature stability and rutting resistance of asphalt mixtures. This study aimed to give a comparative analysis of the viscoelastic improvement effect of crumb rubber and reclaimed asphalt pavement. In laboratory tests, 2 virgin binder contents, 2 crumb rubber contents, 2 sources of reclaimed asphalt pavement, and 2 reclaimed asphalt pavement contents were involved to produce 12 different types of asphalt mixtures with controlled aggregates gradation. Single axle creep test and dynamic modulus test were conducted to acquire stress-strain response under static and dynamic loading conditions. Creep performance was obtained under 20 °C, 35 °C and 50 °C, and dynamic modulus was obtained under 5 °C, 20 °C, 35 °C and 50 °C at 0.1 Hz, 0.5 Hz, 1 Hz, 5 Hz, 10 Hz and 25 Hz. Master curves were constructed for creep compliance, complex modulus, phase angle, storage, and loss modulus in the time and frequency domains, and an optimal fitting model was selected. As a result, it was found that both crumb rubber and reclaimed asphalt pavement had a positive effect on the elasticity of the asphalt mixture. In most scenarios, the elasticity improvement was dominated by reclaimed asphalt pavement but it was dependent on the aged binder content. The effect of incorporating crumb rubber and reclaimed asphalt pavement together was comparable to the sum of the effect when incorporating each of them solely

Numerical Prediction Model of Runway-Taxiway Junctions for Optimizing the Runway Evacuation Time

It is vital to ensure efficient and fast connection networks that guarantee the development of society in the global atmosphere. Air transport and airport operations play fundamental roles that help to achieve the needs of globalized society, constituting a pillar for providing essential services to a great number of passengers and goods around the world. In the coming years, air industry is expected to expand due to the imminent increase of passengers. This growth in air passenger journeys demands several measures to be applied in airports worldwide. Air traffic must comply with great levels of safety and efficiency according to existing standards to guarantee optimal airport operations. Moreover, airport infrastructures, such as runways and taxiways, should be continuously improved to minimize the possible costs and probability of associated risks, and to maximize their capacities by re-evaluating their designs to cope with the demands derived from the growth in traffic forecasted for the future. In this regard, a prediction model to simulate the behavior of aircraft in landing was developed, allowing to predict the optimum locations of runway-taxiway junctions, enhancing the efficiency of the runway, and minimizing the runway evacuation time. This model is based on tire-fluid-pavement interactions that govern the dynamic behavior of the aircraft during landing in wet and dry pavement conditions. The results provide the accurate landing distance required for operating aircraft inside the airport, which can be used to design enhanced capacity runways, while guaranteeing the safety of operations by minimizing the related accidents probabilities