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In this study, a large-scale laboratory test was developed to analyze the contribution of geogrid reinforcement to the improvement of unpaved roads. A detailed experimental protocol was established regarding the road base soil preparation, installation, and soil compaction procedure. Eight tests were performed under a circular plate load test in a box 1800 mm in width, 1900 mm in length, and 1100 mm in height. Under this configuration, three repeat tests were performed to verify the developed protocol. Furthermore, the plate load tests were used to compare different road base thicknesses and geogrid types. Once the developed protocol was confirmed, three tests, using the developed simulator accelerator of traffic (SAT), were performed. Indeed, the same road base configuration was tested, but this time it was placed in a box 5000 mm in length. The prepared road base was subjected to two different loadings: a specific plate load and a traffic load. The results showed the efficiency of the geogrids, the influence of the road base thickness, and the role of the loading type. Moreover, it demonstrated different mobilized mechanisms of the geogrid, depending on the type of product.

Grounds subjected to cyclic loading, either continuous or fragmentary, widely exist in natural deposits and at reclaimed sites, e.g., induced by traffic loads, earthquakes, and wave-induced loading environments. Assessing the ground deformation under cyclic loading conditions is necessary for proper design and maintenance planning for traffic services. Accordingly, a testing program, in which vertical, horizontal, and shear stresses are automatically controlled, were newly developed in this study to reproduce the actual cyclic traffic load conditions using a hollow-cylindrical torsional shear apparatus. Estimations based on the results obtained from cyclic triaxial stress conditions were seen to underestimate the ground settlement compared to actual stresses, with combined vertical, horizontal, and shear stresses. Two kinds of vertical strain arose after a certain number of cycles: incremental collapse, in which unstable deformation (failure) is caused, and plastic creep, in which deformation continues to accumulate with the dampened rate (per cycle). The number of cycles of combined vertical, horizontal, and shear stresses necessary to reach a certain vertical strain increased linearly on a logarithmic scale when the magnitude of loading decreased. Moreover, the relationship between vertical strain and excess pore water pressure presented the same trend independent of the magnitude of loading. Practical uses of the obtained results were proposed and discussed.

The concrete pavements are often attacked by the coupling function of various factors, such as the coupling function of traffic load and temperature. This study aims to understand the microstructure properties of concrete under fatigue load and temperature coupling effect, including low temperature ( − 22 °C to − 10 °C) and high temperature (32 °C–40 °C) conditions. The flexural strength and the chloride penetration of concrete were tested during the fatigue loading test and coupling test. And the microstructure characteristics of pores, micro-cracks, and ITZ-structure were also investigated. The results show that the coupling function has significant influence on properties of concrete. Both the macroscopical performance and micro-structure of concrete degrade significantly with the increase in exposure time of coupling effect. However, different deterioration mechanism of concrete can be observed in low temperature and high temperature conditions, respectively. Besides, the correlations between macroscopic properties and microstructure of concrete were investigated. It is suggested that the micro-crack and ITZ-structure are the major factors influencing the macroscopic properties of concrete.

The quality-of-service (QoS)/quality-of-experience (QoE) demands of mobile services are soaring and have overwhelmed the obsolescent capability of 3G and 4G cellular networks. The emerging 5G networks will bring an unprecedented promotion in transmission data rates. However, the satisfaction of some service requirements is still in dilemma, especially the end-to-end (E2E) latency which varies in different applications. Multi-access edge computing (MEC), a promising technology in 5G cellular networks, can provide ultra-low E2E latency and reduce traffic load on mobile backhaul networks. The potential benefits of MEC for 5G and beyond services have been explored by preliminary studies. What remains is the uncertainty of revenue from the investment of MEC which will shake operators’ decisions about whether and how to deploy MEC in cellular networks. In this light, this paper designs a MEC-assisted 5G and beyond ecosystem inclusive of three players: private (local) telecom operators, backhaul, and cloud service owners. We propose a revenue maximization model for private (local) telecom operators and cloud service owners to minimize the cost from the end-user perspective while satisfying the latency requirement. The derived model indicates that two players’ revenues can be maximized by optimizing MEC resources and backhaul capacity. The game-theoretic analyses also reveal the optimized hybrid strategy of MEC and cloud for efficient mobile traffic management.

Urban railway networks have an important role in increasing the mobility of urban populations while decreasing congestion and pollution. Railway network extension that is caused by urban growth requires additional specialists and equipment for the operation, which causes an increase in maintenance cost. A comprehensive review of the literature regarding the application of facility location problem (FLP) in the railway domain found that there are few studies, and most of the current research involves the maintenance of railway vehicles only. In this paper, the purpose of this study is to determine the optimal location of infrastructure maintenance depot (IMD) for storing special vehicles and to support the inspection and maintenance tasks in a timely and efficient manner. For a challenging problem that should reflect the characteristic that traffic load and the deterioration of railway tracks are proportional, we proposed a method of applying maintenance weights to the p-hub median problem. To examine the proposed model, the test network was constructed by collecting information on the Seoul metropolitan subway. The results of case studies show that the number and location of IMDs are significantly affected by maintenance demand and expanded network.

A novel lever piezoelectric energy harvester (LPEH) was designed for installation in an actual roadway for energy harvesting. The model incorporates a lever module that amplifies the applied traffic load and transmits it to the piezoelectric ceramic. To observe the piezoelectric growth benefits of the optimized LPEH structure, the output characteristics and durability of two energy harvesters, the LPEH and a piezoelectric energy harvester (PEH) without a lever, were measured and compared by carrying out piezoelectric performance tests and traffic model experiments. Under the same loading condition, the open circuit voltages of the LPEH and PEH were 20.6 and 11.7 V, respectively, which represents a 76% voltage increase for the LPEH compared to the PEH. The output power of the LPEH was 21.51 mW at the optimal load, which was three times higher than that of the PEH (7.45 mW). The output power was linearly dependent on frequency and load, implying the potential application of the module as a self-powered speed sensor. When tested during 300,000 loading cycles, the LPEH still exhibited stable structural performance and durability.

This paper proposes a delay-balanced adaptive channel allocation (DB-ACA) mechanism for improving the channel access performance of an LTE-U and WiFi coexistence system. To support the DB-ACA mechanism, an integrated network architecture is introduced for coordinating the channel access in the coexistence system. Based on the integrated network architecture, the coexistence system is able to adaptively adjust the number of unlicensed channels allocated to the LTE-U system and WiFi system, respectively, according to the current traffic load status of the coexistence system. To ensure the access fairness of the LTE-U and WiFi systems, the DB-ACA mechanism introduces a fairness criterion, which requires that the channel access delay be balanced on the unlicensed band between the LTE-U and WiFi systems. Theoretical models are developed to determine the number of unlicensed channels that need to be adjusted, and performance models are derived to analyze the blocking probability and access delay of the LTE-U system and WiFi system, respectively. The effectiveness of the performance models is validated through simulation results. It is demonstrated through numerical results that the proposed DB-ACA mechanism can effectively ensure access fairness of the coexistence system, and significantly improve the system performance in terms of the blocking probability and access delay.

A circular piezoelectric pavement energy acquisition device for road was designed by using the stack mechanism on a piezoelectric ceramic unit. Two different orientations of piezoelectric transduce...

By caching multiple copies of the sensed data and suppressing repeated content deliveries from the sensor nodes, the in-network caching exhibits strong potentials to reduce energy consumption and avoid service loss in the Internet of Things (IoT). In this paper, we review the fundamentals of the in-network caching in IoT, especially the deployment principles of the cache-enabled brokers. Since in-network caching is not the optimal choice in some cases, we propose the dynamic in-network caching scheme to decide whether the sensed data should be cached in brokers or not, where the location and delay requirement of the clients, traffic load of the brokers as well as the energy level of the sensor nodes are encapsulated in the proposed scheme. Next, we give a practical case study to demonstrate the effectiveness of the proposed in-network caching scheme in the IoT scenario. It shows that the proposed caching scheme is superior to the traditional sensor-to-client scheme in terms of energy saving. Finally, we conclude this paper, and summarize the future research directions to achieve the in-network caching for implementing the green IoT.

The article considers the influence of the randomness of traffic load on the fatigue of elements of steel bridge structures. The phenomenon occurs specifically in the case of bridges characterized by significant width, with many traffic lanes and a high vehicle velocity, especially in the case of heavy goods vehicles. It has been shown that underestimation of operational durability, including fatigue durability, can be up to 23%. Operational loads increase due to the overlapping of traffic loads, which leads to the increased fatigue of elements of steel bridge structures. In an effort to assess this influence and its value, elements of the problem of the randomness of road traffic loads were compiled and described, and a simulative analysis of the operational strength of various lengths (spans) of the main girders of bridges was carried out. The analyses showed that for the structures with spans length of up to 10.0 m, the influence of passing vehicles could be skipped in calculations, especially in the case of weak traffic.

Multi-lane factor (MLF) is a probability reduction reflecting unfavorable traffic loads over multiple lanes acting simultaneously on the most adverse position of a bridge. It is one of the key components of traffic load models for bridges. The most recent research established a multi-coefficient MLF model that clearly illustrated the lane load disparity and the probability reduction of their simultaneous actions. However, it used the block maxima (BM) method for extreme value modeling, which requires a large amount of traffic data. This study aims to adopt the peaks-over-threshold (POT) method to obtain more information from short-term traffic data and model the extreme coincident lane load effects (LLEs) for multi-coefficient MLF calibration. First, the multi-coefficient MLF model was reviewed. Thereafter, the bivariate POT method for coincident LLEs modeling using generalized Pareto distribution was proposed and formulated. Critical issues such as bivariate threshold selection and parameter estimation were addressed. Numerical examples were demonstrated to verify and validate the approach. Finally, the proposed approach was applied for calibrating the MLF of an experimental site with four traffic lanes. The results indicated that the coincident LLEs modeling using the POT approach was accurate and more effective than using the BM method when applied to limited data. The calibrated MLFs from the experimental site effectively revealed the lane load disparity of traffic loads over multiple lanes, which is not involved in the traffic load models of current bridge design specifications. Furthermore, the influence of other problems such as weight restriction on coincident LLEs modeling and MLF calibration were discussed. The proposed technique provides a sound approach for multi-coefficient MLF calibration of bridge assessment with short-term site-specific traffic data.

Fatigue cracking is one of the key distress types, caused by traffic load repetition generating stresses and strains in asphalt layers. In response, polymer modified asphalt (PMA) has been widely u...

Road pavements continuously deteriorate mainly due to the combined influence of traffic load and environmental conditions. The pavement ability to satisfy the road user demands along its designed t...

The aim of this paper was to improve the understanding of the influence exerted by geosynthetic reinforcement on stress and strain states in typical semi-rigid pavement structures subjected to traffic loading. A comparison of traffic-load-induced settlements of pavements with and without reinforcement is presented. The pavement-subgrade structure was modelled as a two-dimensional three-layer system using the finite element method. The behaviour of such structures was analysed in terms of ground compaction. A model of soil compaction was used to predict pavement deformation under repeated traffic loading. A series of numerical simulations were conducted to investigate the settlements of pavements with and without reflective cracks. It was assumed that reflective cracks propagate from the base layer to the pavement surface. The main attention was focused on the positive effect of the inclusion of reinforcement in pavements on the behaviour of such structures under traffic loading. The influence of such factors as subgrade properties, the magnitude of traffic loading and the presence of cracks in the pavement structure on stress and strain states was investigated. It was confirmed that placing a geosynthetic reinforcement layer inside the bituminous layer leads to a significant reduction in pavement settlements.

Cloud platforms could automatically scale underlying network resources up and down in response to changes in the traffic load. Such an auto-scaling mechanism can largely enhance the elasticity and scalability of cloud platforms. However, it may introduce new security threats. For example, the Yo-Yo attack is a newly disclosed attack against the cloud auto-scaling mechanism. Attackers periodically send bursts of traffic to cause the auto-scaling mechanism to oscillate between the scale-up process and the scale-down process, which may result in significant performance degradation and economic loss. None of the prior work addressed the problem of mitigating such an attack. In this paper, we propose a Trust-based Adversarial Scanner Delaying (TASD) approach to effectively and proactively mitigate the Yo-Yo attack on the cloud auto-scaling mechanism. In TASD, we first propose to use the trust-based scheme to establish trust values for users, which is leveraged to identify adversarial requests. Trust values are updated by jointly considering the request mode and the auto-scaling status. Then, we aim to disable the condition under which the Yo-Yo attack takes effect by injecting certain delay, under the QoS constraints, to manipulate the response time of suspicious requests and deceive the attackers. Our extensive evaluation demonstrates that our approach achieves promising results, e.g., it can detect at least 80 % Yo-Yo adversarial users and reduce more than 41 % malicious scale-ups.

In recent years, piezoelectric technology for recovery of road vibration energy has gained widespread attention. Most research in this field thus far has examined different piezoelectric materials and evaluated their feasibility in field tests, but less attention has been devoted to different transducer structures. In this study, a new type of Tile transducer was developed for roadway applications. The Tile transducer exhibited good vibration absorption effect and energy harvesting efficiency at low-frequency vibration. This study tested the Tile transducer under the supported boundary condition, and analyzed the influence of the curvature of the Tile transducer on the energy harvesting efficiency with regard to the electromechanical conversion performance and structural strength. When the excitation frequency was 10 Hz and load was 500 N, the total power of the Plane transducer was 0.59 mW. Under the same load condition, the total power of the Tile transducer was 15.44 mW, which was 26-fold higher than that of the Plane transducer. An ultimate compressive bearing capacity test and fatigue test of the Tile transducer were then carried out, and the fatigue failure mode was analyzed. The test results prove that the Tile transducer had stable and lasting structural performance.

The traffic load has grown significantly in recent years, which might be a threat for the service safety of existing bridges. Thus, it is an urgent task to assess the actual traffic load effects on bridges, considering actual heavy traffic load instead of design traffic load. This study presents a framework for extrapolating maximum dynamic traffic load effects on large bridges using site-specific traffic monitoring data. The framework involves vehicle–bridge interaction analysis and probabilistic modelling of extreme values. The weigh-in-motion measurements of a busy highway in China were collected for stochastic traffic load modelling. Case studies of two long-span cable-supported bridge based on the weigh-in-motion measurements were conducted to demonstrate the effectiveness of the proposed framework. It is demonstrated that Rice’s level-crossing approach can capture both dynamic and probabilistic characteristics of the traffic load effects. The root-mean-square displacement of the cable-stayed bridge follows a C-type distribution, and the one for the suspension bridge follows an M-type distribution, which is associated with the first-order mode shapes of the two types of bridges. The amplification factors for the cable-stayed bridge and the suspension bridge are 5.9% and 3.6%, respectively. The numerical analysis indicates that the dynamic effect for extrapolation is weaker with the increase in bridge span length, but the effect of traffic volume growth will be more significant.

Mobile ad-hoc networks (MANETs) are composed of mobile nodes communicating through wireless medium, without any fixed centralized infrastructure. Providing quality of service (QoS) support to multimedia streaming applications over MANETs is vital. This paper focuses on QoS support, provided by the stream control transmission protocol (SCTP) and the TCP-friendly rate control (TFRC) protocol to multimedia streaming applications over MANETs. In this study, three QoS parameters were considered jointly: (1) packet delivery ratio (PDR), (2) end-to-end delay, (3) and throughput. Specifically, the authors analyzed and compared the simulated performance of the SCTP and TFRC transport protocols for delivering multimedia streaming over MANETs. Two simulation scenarios were conducted to study the impact of traffic load and node speed (mobility) to their performance. Based on the simulation results, the authors found that the PDR and the end-to-end delay of TFRC are slightly better than those of SCTP in both scenarios. Additionally, the performance of SCTP is significantly better than TFRC in terms of throughput.

This study introduces a simplified model for bridge-vehicle interaction for medium- to long-span bridges subject to random traffic loads. Previous studies have focused on calculating the exact response of the vehicle or the bridge based on an interaction force derived from the compatibility between two systems. This process requires multiple iterations per time step per vehicle until the compatibility is reached. When a network of vehicles is considered, the compatibility equation turns to a system of coupled equations which dramatically increases the complexity of the convergence process. In this study, we simplify the problem into two sub-problems that are decoupled: (a) a bridge subject to random Gaussian excitation, and (b) individual sensing agents that are subject to a linear superposition of the bridge response and the road profile roughness. The study provides sufficient evidence to confirm the simulation approach is valid with a minimal error when the bridge span is medium to long, and the spatio-temporal load pattern can be modeled as random Gaussian. Quantitatively, the proposed approach is over 1,000 times more computationally efficient when compared to the conventional approach for a 500 m long bridge, with response prediction errors below $0.1\%$., submitted to the Journal of Civil Structural Health Monitoring

Multi-lane factor (MLF) is a crucial component of the traffic load model in design specifications for bridges. Due to the significant changes in highway freight transportation over the past two decades, it is urgent to propose precise MLFs for bridge assessment under onerous traffic loading. This study reviews the underpinning approaches of existing MLF models and uses numerical examples and site-specific weigh-in-motion data to investigate the performance of these approaches. First of all, three MLF underpinning approaches described in the literature, i.e., the multi-presence truck weights approach, the multi-presence truck load effects approach, and the coincident lane load effects approach, are illustrated and discussed. Then, numerical examples of multi-lane bridge traffic load effects without lane load disparity are used to compare the MLFs calibrated by the three approaches. Finally, realistic weigh-in-motion data that have a strong lane load disparity are employed to calibrate MLFs by these approaches, and the MLFs are compared with those in bridge design codes. Results show that the three approaches have large deviations on MLFs calculation based on the same traffic data and studied bridges. In general, the coincident lane load effects approach is flexible for MLF calibration of traffic data with and without lane load disparity. However, its calculation procedure is relatively complicated, especially when the number of traffic lanes is large. The multi-presence truck load effects approach gives comparable results of traffic data without lane load disparity but overestimates MLFs when there is lane disparity of traffic loads over multiple lanes. The multi-presence truck weights approach needs to be improved for traffic data with and without lane load disparity otherwise generates large deviations. The selection and improvement of the three approaches are further discussed. This work highlights the importance of MLF approaches to consider the lane disparity of traffic loads over multiple lanes in practical engineering.

Continuous and real-time tension force monitoring is a key point in fatigue damage evaluation for bridge suspenders or hangers. Usually, effective sensors are not equipped in suspenders or hangers ...

The Majiagou Bridge comprising four sub-bridges is adjacent to the Weiqiang coal mine, Yulin City, Shaanxi Province, China. The mining of the longwall panel No. 1307 may damage the Majiagou Bridge. In this study, we predicted the mining-induced bridge movements using the finite element method (FEM) to examine whether the progressive mining of the longwall panel will pose a negative impact on the Majiagou Bridge. We reconstructed detailed three-dimensional models of the four sub-bridges by considering the superstructures and substructures. The input mechanical properties of the strata are estimated by calibrating with available field monitoring data. Effect of traffic load on the bridge subsidence is also accounted. The numerical predictions are: (1) after the panel No. 1307 is mined, the maximum vertical and horizontal displacements of the four bridges are 61.2 mm and 84.8 mm respectively, which occur on the sub-bridge D that is closest to the longwall panel, (2) traffic load has much less pronounced effect on the Majiagou Bridge than that due to mining, and (3) the maximum tilt and horizontal strain of the sub-bridges are 3.42e−5 m/m and 2.19e−5 m/m, which occur on sub-bridge B and sub-bridge A, respectively. In terms of tilt, the Majiagou Bridge is safe whereas it is to be damaged in terms of horizontal movement that is more critical in causing structural damage. Therefore, we suggest that a reasonably wider protective coal pillar should be set if the panel No. 1307 is to be mined, to ensure the safety of the Majiagou Bridge.

With the tremendous increase in the amount of network contents and emerging applications, traditional network architecture starts to exhibit management and efficiency problems. The evolving STIN, as a combination of satellite networks and terrestrial networks, also faces similar obstacles. To address this challenge, technologies like ICN and SDN, which were initially proposed for terrestrial networks, could provide viable and promising solutions in STIN. In this article, we propose a novel architecture to provide flexible management and efficient content retrieval for STIN. Our architecture consists of a three-layer satellite network in which satellites of each layer are assigned to different functionalities. In order to achieve compatibility with ICN, we also design a new on-board switch based on protocol oblivious forwarding switch. In so doing, the proposed architecture inherits the advantages of ICN and SDN. Additionally, concerning the issue of the most traffic contribution in content retrieval applications, we propose a simple yet effective cooperative content retrieval scheme for terrestrial users. Furthermore, to make the best use of in-network caching and achieve further efficiency improvement of content retrieval, a cooperative caching scheme and a coded caching scheme are also proposed. The feasibility of these caching schemes is analyzed, and numerical evaluations show that the proposed content retrieval schemes in this architecture can achieve significant traffic load reduction.

The paper attempts to use the motorization levels for analyzing the increase in traffic volume across road links and network for roads of various hierarchies. Using a gravity model approach and traffic volume and flow survey along the nodes and links, it found that increase in per capita vehicle ownership leads to relatively higher increase in traffic load and the relationship can be used to predict the future traffic projections, based on motorization levels of the residents and the traffic zones. Further, predicting motorization level by using economic and income indicators can link, increase in traffic demand with economic and other welfare policies allowing planning of long term of infrastructural development.

Introduction: Variation laws of dynamic response and settlement deformation at different depths of soil roadbed were investigated and summarized in this study through a simulation test with a dynamic model groove in soft clay foundation of low road embankment. Materials and Methods: In this test, the traffic load was simulated by single-point and double-point shock excitation. Besides, loading frequency, intensity and duration were adjusted by a single variable control method. Research results show that peak values of soil pressure and pore water pressure decrease with the increase of buried depth, but they are unrelated to loading intensity and frequency. Conclusion: Nevertheless, settlement deformation does not increase linearly with the increase of frequency or time difference. The accumulative settlement at a depth varies as the loading time increases.

In permeable pavement systems, open-graded aggregates are commonly used for base and subbase layers that allow water to store and drain. At each traffic load cycle, the permanent strain accumulates...

The road-base usually deteriorate during service time due to factors such as cyclical traffic loads and road-base fouling. Currently the monitoring method for road-base quality is quite limited. This paper proposes a real-time Monitoring method for Road-Base Quality (MRBQ) based on a soil dynamic model and piezoelectric sensors buried in road-base. The soil dynamic model was extended with a piezoelectric equation to calculate the voltage in the road-base generated by a moving traffic load. Then, a model test was conducted to measure the output voltage of the piezoelectric sensors buried in the road-base. Finally, the road-base modulus was back-calculated through the soil dynamic model with the measured voltage. The back-calculated modulus was compared with the modulus measured by resonance column test (RCT) to validate this method. The unique relationship between the peak voltage and the road-base modulus at various depths was identified for different traffic load amplitudes and speeds, and the feasibility and accuracy of the MRBQ was demonstrated. This study reveals that the sensitivity of the piezoelectric sensors can reach 2 V/MPa, and the error to measure the road-base modulus is less than 20%. The proposed MRBQ demonstrates a good application potential in health monitoring of transportation facilities.

Wireless communication between public safety officers is very important to transmit voice or data during emergency crises. When the public communication networks cannot provide services during crises, disasters, and high traffic cases, Professional or private mobile radio (PMR) such as Association of Public Safety Communications Officials (APCO25) conventional systems are needed to improve the service quality and to provide uninterrupted service to the users. In this paper, we propose traffic-based cell selection algorithms for the APCO25 conventional systems to attach users to base stations in a balanced manner to reduce waiting time while establishing a connection. The simulation results of the proposed traffic load–based cell selection algorithms are illustrated in terms of the RSSI measurements counter, the number of connection requests, the average waiting time, and the number of re-selections for the APCO25 conventional systems.

A large number of high embankments have been constructed in highway engineering with the fast development of highway. The measurement and treatment of traffic loading-induced settlement is a research focus in recent years. This paper focuses on the measurement of the layered settlement, induced by the traffic loading, in the embankment of highway. A novel method to measure the traffic loading-induced settlement at different depths in the embankment is proposed. The practical measurement equipment, including a multipoint extensometer, rigid base, settlement detecting plate, protector tube and connecting rod, is developed. The field tests were carried out in the filling and surcharge period to verify the stability and accuracy of measurement equipment. The test results indicate that the developed equipment and the presented installation method can be capable of measuring traffic-induced settlement at different depths in the embankment of the operating highway.

In this paper, we propose a millimeter-wave-based cooperative backhaul scheme for a mobile X-haul distributed unit (XDU), whose line of sight for backhaul data reception is not always guaranteed in an X-haul network. Since the received signal at the mobile XDU experiences severe path loss than other stationary XDUs, the proposed scheme selects one of stationary wireless XDUs as a relay for assisting the mobile XDU. The relaying XDU selection takes into account not only the location information, but also the load information of wireless XDUs. We derive the outage probability of the mobile XDU and show that the proposed scheme outperforms the conventional relay selection scheme without taking account of the traffic load on relaying nodes.

The paper focuses on the issue of using reclaimed asphalt (RA) in asphalt mixtures used for highly traffic-loaded asphalt pavements—in asphalt mixtures of the stone mastic asphalt (SMA) type. It is a skeleton-type mixture, where the traffic load is bore by a skeleton of coarse aggregates bonded with mastic (i.e., bitumen and fine aggregates). It is therefore essential to pay close attention to the properties of this coarse aggregate. Higher demands on properties of the aggregate are probably due to the fact that RA is not currently being used in SMA-type mixtures. Most standards do not allow usage of RA in this type of mixtures. Given that traffic load of road networks is constantly increasing, the ratio of SMA-type asphalt mixtures also increases in the road network. This paper presents results of 5-year research focused on the possibility of using RA in SMA-type asphalt mixtures. This included laboratory design of these mixtures with various dosages and types of RA. Their empirical and functional properties were verified. Based on the positive results of the laboratory testing, a test section was subsequently constructed using several variants of the mixtures containing up to 50% of RA. This test section is regularly being monitored, and despite very intense traffic load, there are no failures apparent after 2 and half years of operation. Based on the laboratory research and subsequent construction and monitoring of a test section, it can be said that RA can be used in SMA-type mixtures without any negative impacts on functional properties or mixture lifetime.

Multiple lane presence reduction factors are widely used in traffic load models for bridge design to account for the reduced probability of multiple heavy vehicles occurring simultaneously in adjacent lanes. It is custom to reduce the single lane loading by a reduction factor with a value less than one which further reduces as the number of loaded lanes increases. The values of these factors currently published in design codes tend to be based on many assumptions due to previous lack of data. This paper describes a novel method to determine reduction factors based on Extreme Value statistics and multiple lane Weigh in Motion data. The method compares load effects in parallel lanes at characteristic level and avoids traffic composition and multiple presence assumptions made in previous works which were necessary due to the absence of good quality multiple lane data. As the method is based on Weigh in Motion data it also accounts for the possibility of multiple vehicles in any one lane. The method does not rely on dependence or independence between lanes.

This paper presents a study regarding the consequences of traffic loads, including the ones due to traffic overload and traffic efficiency, on the damage of flexible road pavements. It was based on...

Permanent, inelastic deformations of one or several pavement and subgrade layers originate from insufficient material (mix rutting) or structural design (subgrade rutting) of the asphalt pavement setting subjected to periodic traffic load (frequency- and load-dependent). Several studies revealed that the correct numerical assessment of the complex tire-pavement interaction (detailed consideration of tire and pavement) is crucial for reliable and accurate long-term predictions. In this contribution, the structural long-term response of asphalt pavements (modeled as elastoplastic solid at large strains) under periodic traffic load is thermo-mechanically investigated within the finite element method (FEM). To efficiently predict irreversible, permanent deformations of the pavement surface due to repetitive tire overrun, the time homogenization technique in combination with an Arbitrary Lagrangian Eulerian (ALE) formulation for the finite element (FE) discretized tire and pavement structures is employed. Time homogenization is used to deal with different time scales in the response of the tire-pavement system to short-term loading (tire overrun), day-night as well as seasonal temperature changes over several years. Different aspects and influence quantities for the problem considered are discussed and enable a qualitative prediction of pavement rutting via a fully FE based approach for tire and pavement instead of traditionally used mechanistic-empirical (M-E) approaches.

This paper reveals the existence of “alternative pair” in the airport network. The alternative pair is defined as a pair of airports that, if one of them is closed, the other one can take over part of its traffic load. We find these pairs of airports important as the network performance will not be affected largely if only one airport is disrupted, while simultaneous closure of both airports in an alternative pair will worsen the network performance significantly, as no other airports can accommodate their load. A method is provided to identify the alternative pairs in an airport network and quantify the “alternative strength” between them. The alternative relations between different airport pairs are visualized using the “alternative graph”. By setting different thresholds of alternative strength, the alternative graph exhibits various patterns. The proposed method is applied to two domestic airport networks to obtain some managerial insights. It is found that airport networks are usually robust to the disruption of a single airport, but vulnerable to the simultaneous disruption of an alternative pair; furthermore, the two airports in an alternative pair may not be geographically close to each other in some airport networks.

The primary objectives of the design and implementation of asphalt pavement on road and road surfaces are to achieve the best performance in different climatic conditions. Asphalt pavement performance depends on the adhesion and bonding of binder and aggregates that the moisture causes it to disappear and it results in bleeding and stripping. Although the moisture susceptibility mechanism is not fully known, factors such as binder properties, aggregates properties, asphalt mixture properties, quality control during congestion, the dynamic effect of traffic load and the type of anti-stripping additive play a significant role in creating a moisture susceptibility and aggravation of failures. In this paper, Group Method of Data Handling (GMDH)-type neural networks have been used for modeling and prediction of moisture susceptibility of nano silica-modified asphalt concrete. To achieve this goal, 5 types of mixtures with different percentage of nano-silica (0, 0.2, 0.4, 0.7 & 0.9%) were prepared and the moisture susceptibility of modified mixtures was evaluated. Results showed that nano-silica can improve the moisture susceptibility of asphalt mixtures. For modeling, the experimental data were divided into train and test sections (70% for training and 30% for testing). The predicted values were compared with those of experimental values in order to estimate the performance of the GMDH-neural network. The model values showed a very good regression with the experimental results.

Railway crossings are subjected to a severe load environment leading to damage and degradation of rail profiles. The damage is the result of the high magnitudes of contact pressure and slip generated in the wheel–rail contacts during each wheel transition between wing rail and crossing nose. In this paper, numerical predictions of the long-term accumulation of plastic deformation and wear are presented and compared for two rail grades used in crossings. The comparison is performed using a framework that includes simulations of dynamic vehicle–track interaction, wheel–rail contact and rail damage. A load sequence generated by means of Latin hypercube sampling, taking into account variations in worn wheel profile, vehicle speed and wheel–rail friction coefficient, is considered. A Hertzian-based metamodel for wheel–rail normal contact accounting for inelastic material response is used for the simulation of wheel–rail contact. The methodology is demonstrated by calculating the plastic deformation for one cross-section of the crossing nose using an Ohno-Wang cyclic plasticity model, while wear is predicted by means of the Archard model for sliding wear. For the studied conditions and after the simulation of 41400 load cycles, representing an accumulated traffic load of 0.8 MGT, it is concluded that the fine-pearlitic rail grade R350HT experiences half of the ratchetting strain compared to the austenitic hot-rolled manganese steel Mn13. Based on a wear model calibrated for Mn13, the maximum wear of the studied cross-section is about 2% of the maximum plastic deformation.

A calibrated mechanistic-empirical model was developed to analyze top-down cracking (TDC) performance with actual traffic load and thermal stress. The traffic-induced and thermal-induced J-integral were employed in the Paris’ law with fracture parameters A ′ and n ′ estimated using asphalt mixture properties. Number of days for initiated TDC to reach the medium severity level was then calculated mechanistically, which was related to field performance for calibration purposes. It was observed that when TDC reached a critical length, the TDC length diminished and area of fatigue cracking increased. An associated computer program was also developed, which normally completed a 30-year performance analysis within 1 min.

Libya use a volumetric analysis in designing asphalt mixtures, which can also be upgraded in hot weather. However, the condition of some roads was further down than the required level. Rutting is one of the major defects that occur in asphalt pavements in the southern desert of Libya and severely influence the drive-ability. A questionnaire surveys and laboratory experiments were performed for a few mixes under representative temperature and traffic load. In laboratory, rutting test conducted on two different asphalt mixtures. The first mix used an asphalt binder B (60/70) at optimum bitumen content, another mixture developed using the Superpave design procedure with the same materials and performance asphalt binder grade PG (70-10). The questionnaire survey was distributed to 55 engineers and specialists in the field. The interview was conducted to a few others and the factors that leading to poor performance of asphalt roads were listed. Considering and improving of these factors will play an important role to improve the pavement performances, longer service life and lower maintenance costs. Asphalt concrete pavements (ACP) should use asphalt binder which is less affected by pavement temperature change and traffic load. The properties of the mixture, in turn, affect the pavement performance. Keywords - asphalt mixtures, consistency, performance, (PG), construction.

A series of cyclic torsional shear tests using hollow cylinder apparatus (HCA) were performed to investigate the effect of principal stress rotation (PSR) on the stress–strain behaviors of saturated soft clay. The traffic–load–induced shear stress path was used in the cyclic test and the investigation mainly concerned the influence of PSR on the shear stiffness and non-coaxiality. It indicated that the effects of PSR substantially depends on the magnitude of deviatoric stress (q = {[(σ1 − σ2)2 + (σ2 − σ3)2 + (σ1 − σ3)2]/2}1/2) as well as the intermediate principal stress ratio (b = (σ2 − σ3)/(σ1 − σ3)). At low deviatoric stress, the trajectory envelope of deviatoric strain path translates with a nearly constant size, showing constant shear stiffness and strong non-coaxiality. However, at high deviatoric stress, the trajectory envelope of deviatoric strain rapidly expands towards instability, showing degenerating shear stiffness and weak non-coaxiality. Moreover, the excess pore water pressure increases and the shear stiffness decreases more rapidly as b value increases. The results can provide an experimental basis for constitutive modelling of clays under traffic–induced loadings.

Pavement serviceability is one of the main indicators signaling the safe and fluid traffic of vehicles. Within the Pavement Management System, the pavement serviceability expresses by the instantaneous values of the variable parameters. These parameters are constantly changing depending on climatic conditions and a traffic load of the road. Changes in roughness and unevenness can be derived from experimental stretches or from existing communications. At the University of Zilina, APT - Accelerated Pavement Testing was developed to simulate changes in these parameters. The degradation models thus created can be applied in programs that allow economic and technological evaluation of selected sections of the road.

This article intends to demonstrate the importance of cutting-edge technologies in providing mobile coverage in factories and in industrial buildings. The current paper examines indoor and outdoor radio network systems and investigates already operating mobile networks, as well as the 5G, which is currently in the state of standardisation [1]. Furthermore, building on the available data transfer rates, current article - relying on the standardisation process – estimates the preference of the 5G within manufacturing. In the world of IoT (Internet of Things) [2], M2M (Machine-to-Machine Communication) [3] and Smart Factories [4], the available mobile networks most likely will not be able to handle the high traffic load sufficiently [5]. The article seeks to answer whether the development of new mobile technologies will be able to support the Industry 4.0 revolution for Smart Factories and manufacturers [6].

Bandwidth-efficient 5G optical fronthaul interfaces, such as the Ethernet-based common public radio interface (eCPRI), with novel low layer split (LLS) are being actively investigated. Regarding the uplink eCPRI, the burdened wireless resource blocks (RBs) are delivered and the traffic aggregation is leveraged; therefore, the eCPRI traffic is highly dynamic depending on the time-varying mobile traffic load. This dynamic property will lower the average fiber link utilization and complicate the sizing of link bandwidth for the deployment of low-latency fronthaul. To tackle this issue, we propose a load-adaptive quantization resolution scheme that enables elastic fronthaul capacity. By adjusting the quantization resolution of the resource elements in RBs, the fronthaul link capacity, measured by the amount of bearable RBs, can be scaled to fit the mobile traffic load. Specifically, a full resolution is applied during low-load period, while for high-load case, to boost the link capacity, a stringent resolution is performed by removing the least significant quantization bits (LSQBs). Besides, to minimize the signal fidelity deterioration caused by the decline of resolution, the resolution redundancy is evaluated based on the detected wireless signal quality at central unit, and the location of LSQBs is fed back to the radio unit through the eCPRI control plane. With the enhanced link flexibility, the required fronthaul bandwidth can be significantly reduced, while the user experience is barely compromised. Based on our developed low-MAC and PHY-layer wireless system model following 3GPP specifications and the 25-Gb/λ experimental fiber transmission, the bandwidth of eCPRI user data can be saved by 40%.

Traffic load monitoring (TLM) is one of important issues in bridge structural health monitoring (SHM), but there still exist such problems as lack of accuracy and efficiency for the existing methods. In this study, a sparse regularization approach is proposed for TLM based on analytical model and redundant dictionary. Firstly, an unknown moving traffic load is deemed as a combination of static and time-varying components so that a redundant dictionary can be established to independently express them. The static component is expressed by a basis vector whose elements are identical, and the time-varying one by wavelet functions for their good multi-resolution analysis characteristics. Then, the TLM problem is converted to determine a coefficient vector of dictionary, and the l 1 -norm regularization technique is adopted to obtain a sparse solution to the coefficient vector. Finally, a series of experimental studies on a hollow steel beam bridge under crossing a moving model car are conducted in laboratory to assess the effectiveness of the proposed method. Furthermore, comparative studies are carried out for assessing the effect of different measurement parameters, such as moving car speeds, car weights, strain and acceleration response data, redundant dictionaries as well as selection of regularization parameters, on the proposed method. The illustrated TLM results show that the dictionary used for TLM in this study can independently distinguish the static and time-varying components of moving traffic loads. The proposed method can effectively identify the total weight of moving traffic loads with a higher accuracy, which provides a great potential for monitoring moving vehicle loads on bridges.

SDN and NFV are collaboratively recognized as the most promising bearing for flexible programmability of network control functions and protocols with dynamic usage of network resources. SDN provides the abstraction of network resources over well-defined APIs to achieve underlying topology-independent multiple tenant networks with required QoS and SLAs. NFV paradigm deploys network functions as software instances, namely, VNFs on commodity hardware using virtualization techniques. In this way, virtual IP functions, such as load balancing, routing, and forwarding or firewall, can operate as VNF in a cloud with a positive outcome in network performance. In this paper, we aimed to achieve traffic load balancing by using a virtual SDN (vSDN) controller as a VNF. With vSDN, when there is uneven and increased load, secondary vSDN controllers can be added to share this load. The need of secondary vSDN is determined and a copy vSDN with exactly the same configurations as original vSDN is created, which operates accurately and shares traffic load balancing tasks with an original vSDN controller. Both vSDN controllers are independently placed in the cloud with transparency assuring that every client in the network is familiar with the existence of the newly created secondary vSDN controller. We experimentally validated the load balancing in Fat-Tree topology using two vSDN controllers in a Mininet emulator. The results showed 50% improvement in average load, 41% improvement in average delay, and considerable improvements in terms of ping response, bandwidth utilization, and throughput of the system.

The initial part of the paper briefly characterizes the present state of the track substructure dimensioning for the non-traffic load and the necessity of updating the design map of frost indexes IFd as a basis for dimensioning. A substantial part of the paper is dedicated to the method of evaluating the data provided by the Slovak Hydrometeorological Institute (SHMI), and determining the dependency of design air frost indexes IFd on altitude for the coldest winter period in the past 50 years. The paper conclusion presents the updated design map of frost indexes and the assessment of the importance of its updating in terms of the track substructure dimensioning methodology for the non-traffic load.

This paper proposes a QoS-guaranteed scheduling algorithm that considers the available resources and traffic load of small cell. Even though the available resources are scarce or traffics to be scheduled are overloaded, Guaranteed Bit Rate (GBR) traffic such as VoIP and video should be supported. The proposed algorithm provides a flexible weight ratio between GBR and Non-GBR traffic according to resources and traffic load. Furthermore, since QoS is considered by simple QoS Class Identifier (QCI), low complexity is achieved. Simulation results show that the proposed algorithm improves QoS including delay and Packet Loss Rate (PLR) performance effectively. Keywords: QoS, Scheduling, Traffic load, Guaranteed Bit Rate, Small cell

This paper proposes an algorithm for the estimation of extreme intensity of traffic load on long-span bridges. Most Weigh-in-Motion technologies do not operate in congested conditions which are the governing cases for these bridges. In the absence of Weigh-in-Motion data on the bridge itself, a correlation between vehicle weights and their lengths is established here using a (free- flowing) Weigh-in-Motion database. Photographic images of congested traffic are modelled here for three bridges using weights estimated from lengths and one year of Weigh-in-Motion data. The actual weights are taken from the Weigh-in- Motion data, and the results are compared to test the method. The gaps between vehicles are firstly set to a constant value and later to Beta-distributed values according to vehicle type. The intensity of traffic load for all pictures is calculated and compared to the loads obtained from the recorded weights. A return period of 75-year is chosen to evaluate the extreme values of intensity. The probability that intensity of load is being exceeded is obtained using normal probability paper for both recorded and simulated weights. This study demonstrates the feasibility of the proposed concept of using lengths to estimate the extreme traffic load events with acceptable accuracy.

This work presents the study of the improving air navigation at chlef aerodrome by Implementing a new Instrument Landing System (ILS). At present, the radio navigation systems at Chlef aerodrome can handle the air traffic load adequately(air traffic controllers are able to manage the airspace for which they are responsible). Nevertheless, in the very near future the traffic load will become so important that it will require the implementation of an ILS beacon. To this reason, we will study the current situation, which is based on a general presentation of Chlef aerodrome (the situation and position of the airspace, and the existing airport infrastructure), followed by the choice of equipment to be installed and the method of implanting the ILS system (composition, technical characteristics and arrangements), in accordance with standards and recommended practices. From these results we can find: Implementation of glide path (GP) on the runway26, implementation of the localizer on the runway 26, setting a new equipment DME. The previous systems contribute largely for improving the air navigation at the aerodrome of Chlef.

Fatigue verification of bridge structures requires information on the loads induced by heavy vehicles, which can be obtained from weigh in motion measurement (WIM) systems. The current fatigue load models applied in Europe are based on traffic load measurements in 1986. This paper evaluates the appropriateness of these models for today’s traffic by comparing their load effects with those of recent WIM databases, covering the years 2008 to 2018. A procedure is derived to determine the required size of the WIM database for a sound representation of the fatigue loads. The effects of traffic jams are evaluated and the required safety margins or partial factors are derived. As already concluded by others, it appears that the most frequently used fatigue load model is unable to represent the fatigue action effects of today’s European traffic. In addition, the paper demonstrates that the other fatigue load models are also inaccurate. A new fatigue load model is proposed that is easy in use and gives a significant improvement in accuracy compared to the existing models. The parameters in this model can easily be calibrated for other WIM databases.