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Most Cited Journal of Traffic and Transportation Engineering (English Edition) Articles

The most cited articles published since 2015, extracted from Scopus.

Applications of terrestrial laser scanning for tunnels: a review

Volume 1, Issue 5, October 2014, Pages 325-337
Weixing Wang | Weixing Wang | Weisen Zhao | Lingxiao Huang | Vivian Vimarlund | Zhiwei Wang

© 2014 Periodical Offices of Chang'an University In recent years, the use of terrestrial laser scanning (TLS) technique in engineering surveys is gaining an increasing interest due to the advantages of non-contact, rapidity, high accuracy, and large scale. Millions of accurate 3D points (mm level accuracy) can be delivered by this technique with a high point density in a short time (up to 1 million points per second), which makes it a potential technique for large scale applications in engineering environments such as tunnels, bridges, and heritage buildings. Tunnels, in particular those with long lengths, create great challenges for surveyors to obtain the satisfactory scanned data. This paper presents a short history of TLS techniques used for tunnels. A general overview of TLS techniques is given, followed by a review of several applications of TLS for tunnels. These applications are classified as: detecting geological features of drilling tunnels, monitoring the geometry of tunnels during excavation, making deformation measurements, and extracting features. The review emphasizes how TLS techniques can be used to measure various aspects of tunnels. It is clear that TLS techniques are not yet a common tool for tunnel investigations, but there is still a huge potential to excavate.

Caltrans use of scrap tires in asphalt rubber products: a comprehensive review

Volume 1, Issue 1, February 2014, Pages 39-48
Haiping Zhou | Sri Holikatti | Peter Vacura

© 2014 Periodical Offices of Chang'an University The California Department of Transportation (Caltrans) has been using scrap tire rubber in asphalt pavements since the 1970s in chip seals and the 1980s in rubberized hot mix asphalt(RHMA). Both the wet (field blend) and dry processes were used in early trials. Caltrans has also used rubber modified binders containing both crumb rubber modifier and polymer modifier that could be manufactured at a refinery facility, a terminal blend wet process. Since the beginning of this century, Caltrans increased the use of scrap tire rubber in paving projects and invested considerable resources in developing technically sound, cost effective, and environmentally friendly strategies for using scrap tire rubber in roadway applications. By the end of year 2010, approximately 31 % of all hot mix asphalt (HMA) placed by Caltrans was rubberized HMA, roughly 1.2 million tons. Caltrans efforts in using asphalt rubber products were also demonstrated in its research and technology development. These included the construction of two full-scale field experiments, five warranty projects, and an accelerated pavement study using a heavy vehicle simulator. Additionally, terminal blend asphalt rubber and rubberized warm mix asphalts began to be experimented on trial basis. This paper provides a comprehensive review of Caltrans experience over four decades with asphalt rubber products. Current practices and future outlook are also discussed.

Behavior of composite rigid frame bridge under bi-directional seismic excitations

Volume 1, Issue 1, February 2014, Pages 62-71
Xiaogang Liu | Jiansheng Fan | Jianguo Nie | Guo Li

© 2014 Periodical Offices of Chang'an University Pushover analysis and time history analysis are conducted to explore the bi-directional seismic behavior of composite steel-concrete rigid frame bridge, which is composed of RC piers and steel-concrete composite girders. Both longitudinal and transverse directions excitations are investigated using OpenSees. Firstly, the applicability of pushover analysis based on the fundamental mode is discussed. Secondly, an improved pushover analysis method considering the contribution of higher modes is proposed, and the applicability on composite rigid frame bridges under bi-directional earthquake is verified. Based on this method, an approach to predict the displacement responses of composite rigid frame bridge under random bi-directional seismic excitations by revising the elasto-plastic demand curve is also proposed. It is observed that the developed method yield a good estimate on the responses of composite rigid frame bridges under bi-directional seismic excitations.

Three-dimensional modeling and simulation of asphalt concrete mixtures based on X-ray CT microstructure images

Volume 1, Issue 1, February 2014, Pages 55-61
Hainian Wang | Zhihan Huang | Lei Li | Zhanping You | Yu Chen

© 2014 Periodical Offices of Chang'an University X-ray CT (computed tomography) was used to scan asphalt mixture specimen to obtain high resolution continuous cross-section images and the meso-structure. According to the theory of three-dimensional (3D) reconstruction, the 3D reconstruction algorithm was investigated in this paper. The key to the reconstruction technique is the acquisition of the voxel positions and the relationship between the pixel element and node. Three-dimensional numerical model of asphalt mixture specimen was created by a self-developed program. A splitting test was conducted to predict the stress distributions of the asphalt mixture and verify the rationality of the 3D model.

A dissipated energy comparison to evaluate fatigue resistance using 2-point bending

Volume 1, Issue 1, February 2014, Pages 49-54
Cinzia Maggiore | Gordon Airey | Paul Marsac

© 2014 Periodical Offices of Chang'an University Fatigue is the main failure mode in pavement engineering. Typically, micro-cracks originate at the bottom of asphalt concrete layer due to horizontal tensile strains. Micro-cracks start to propagate towards the upper layers under repeated loading which can lead to pavement failure. Different methods are usually used to describe fatigue behavior in asphalt materials such as: phenomenological approach, fracture mechanics approach and dissipated energy approach. This paper presents a comparison of fatigue resistances calculated for different dissipated energy models using 2-point bending (2PB) at IFSTTAR in Nantes. 2PB tests have been undertaken under different loading and environmental conditions in order to evaluate the properties of the mixtures (stiffness, dissipated energy, fatigue life and healing effect).

A review of road extraction from remote sensing images

Volume 3, Issue 3, June 2016, Pages 271-282
Weixing Wang | Weixing Wang | Nan Yang | Yi Zhang | Fengping Wang | Ting Cao | Patrik Eklund

© 2016 Periodical Offices of Chang'an University As a significant role for traffic management, city planning, road monitoring, GPS navigation and map updating, the technology of road extraction from a remote sensing (RS) image has been a hot research topic in recent years. In this paper, after analyzing different road features and road models, the road extraction methods were classified into the classification-based methods, knowledge-based methods, mathematical morphology, active contour model, and dynamic programming. Firstly, the road features, road model, existing difficulties and interference factors for road extraction were analyzed. Secondly, the principle of road extraction, the advantages and disadvantages of various methods and research achievements were briefly highlighted. Then, the comparisons of the different road extraction algorithms were performed, including road features, test samples and shortcomings. Finally, the research results in recent years were summarized emphatically. It is obvious that only using one kind of road features is hard to get an excellent extraction effect. Hence, in order to get good results, the road extraction should combine multiple methods according to the real applications. In the future, how to realize the complete road extraction from a RS image is still an essential but challenging and important research topic.

Multi-state supernetworks: recent progress and prospects

Volume 1, Issue 1, February 2014, Pages 13-27
Feixiong Liao | Theo Arentze | Harry Timmermans

© 2014 Periodical Offices of Chang'an University Supernetworks have long been adopted to address multi-dimensional choice problems, which are thorny to solve for classic singular networks. Originated from combining transport mode and route choice into a multi-modal network, supernetworks have been extended into multi-state networks to include activity-travel scheduling, centered around activity-based models of travel demand. A key feature of the network extensions is that multiple choice facets pertaining to conducting a full activity program can be modeled in a consistent and integrative fashion. Thus, interdependencies and constraints between related choice facets can be readily captured. Given this advantage of integrity, the modeling of supernetwork has become an emerging topic in transportation research. This paper summarizes the recent progress in modeling multi-state supernetworks and discusses future prospects.

Finite element model updating of a tied-arch bridge using Douglas-Reid method and Rosenbrock optimization algorithm

Volume 1, Issue 4, August 2014, Pages 280-292
Tobia Zordan | Bruno Briseghella | Tao Liu | Tao Liu

© 2014 Periodical Offices of Chang'an University Condition assessment of bridges has become increasingly important. In order to accurately simulate the real bridge, finite element (FE) model updating method is often applied. This paper presents the calibration of the FE model of a reinforced concrete tied-arch bridge using Douglas-Reid method in combination with Rosenbrock optimization algorithm. Based on original drawings and topographie survey, a FE model of the investigated bridge is created. Eight global modes of vibration of the bridge are identified by ambient vibration tests and the frequency domain decomposition technique. Then, eight structural parameters are selected for FE model updating procedure through sensitivity analysis. Finally, the optimal structural parameters are identified using Rosenbrock optimization algorithm. Results show that although the identified parameters lead to a perfect agreement between approximate and measured natural frequencies, they may not be the optimal variables which minimize the differences between numerical and experimental modal data. However, a satisfied agreement between them is still presented. Hence, FE model updating based on Douglas-Reid method and Rosenbrock optimization algorithm could be used as an alternative to other complex updating procedures.

Wind-vehicle-bridge coupled vibration analysis based on random traffic flow simulation

Volume 1, Issue 4, August 2014, Pages 293-308
Tao Wang | Wanshui Han | Fei Yang | Wen Kong

© 2014 Periodical Offices of Chang'an University A wind-vehicle-bridge system can be regarded as an interaction resuit of wind-bridge interaction, wind-vehicle interaction and vehicle-bridge interaction, which is determined by nature wind, dynamic characteristics of vehicle and bridge structures, interrelationship between bridge and vehicle dynamic properties and so on. Firstly, based on the traffic loading investigation on the expressway bridge within 24 hours a day, and the critical parameters of traffic flow, such as the vehicle type, weight, separation space and speed are and recorded and analyzed to extract its statistical characteristics, which are used to work out random traffic flow simulation program RTF. This RTF program can be embedded with the other general HEM software. Secondly, a dynamic analysis module RTFWVB of the wind-vehicle-bridge coupling vibration under random traffic flow is presented, which can consider arbitrary number of vehicles, multi-lanes and traffic flow direction. Finally, Hangzhou Bay Bridge in China is selected as a numerical example to demonstrate dynamic interaction of the RTFWVB system. The results indicate that the traffic flow direction has just a little influence on bridge dynamic response, that the mean responses are mainly determined by the moving vehicle loads, and that the fluctuating components will increase with the increase of wind speed.

Evaluation system for CO2emission of hot asphalt mixture

Volume 2, Issue 2, April 2015, Pages 116-124
Bo Peng | Chunli Cai | Guangkai Yin | Wenying Li | Yaowen Zhan

© 2015 Periodical Offices of Chang & rsquo;an University The highway construction industry plays an important role in economic and development, but is also a primary source of carbon emission. Accordingly, with the global climate change, energy conservation and reduction of carbon emissions have become critical issues in the highway construction industry. However, to date, a model for the highway construction industry has not been established. Hence, to implement a low-carbon construction model for highways, this study divided asphalt pavement construction into aggregate stacking, aggregate supply, and other stages, and compiled a list of energy consumption investigation. An appropriate calculation model of CO2emission was then built. Based on the carbon emission calculation model, the proportion of carbon emissions in each stage was analyzed. The analytic hierarchy process was used to establish the system of asphalt pavement construction with a judgment matrix, thereby enabling calculation of the weight coefficient of each link. In addition, the stages of aggregate heating, asphalt heating, and asphalt mixture mixing were defined as key stages of asphalt pavement construction. Carbon emissions at these stages accounted for approximately 90% of the total carbon emissions. Carbon emissions at each stage and their impact on the environment were quantified and compared. The energy saving construction schemes as well as the environmental and socioeconomic benefits were then proposed. Through these schemes, significant reductions in carbon emissions and costs can be achieved. The results indicate that carbon emissions reduce by 32.30% and 35.93%, whereas costs reduce by 18.58% and 6.03%. The proposed energy-saving and emission reduction scheme can provide a theoretical basis and technical support for the development of low-carbon highway construction.

Intersection signal control multi-objective optimization based on genetic algorithm

Volume 1, Issue 2, April 2014, Pages 153-158
Zhanhong Zhou | Ming Cai

© 2014 Periodical Offices of Chang'an University A signal control intersection increases not only vehicle delay, but also vehicle emissions and fuel consumption in that area. Because more and more fuel and air pollution problems arise recently, an intersection signal control optimization method which aims at reducing vehicle emissions, fuel consumption and vehicle delay is required heavily. This paper proposed a signal control multi-object optimization method to reduce vehicle emissions, fuel consumption and vehicle delay simultaneously at an intersection. The optimization method combined the Paramics microscopic traffic simulation software, Comprehensive Modal Emissions Model (CMEM), and genetic algorithm. An intersection in Haizhu District, Guangzhou, was taken for a case study. The result of the case study shows the optimal timing scheme obtained from this method is better than the Webster timing scheme.

Calculation of skid resistance from texture measurements

Volume 2, Issue 1, February 2015, Pages 3-16
Andreas Ueckermann | Dawei Wang | Markus Oeser | Bernhard Steinauer

© 2015 Periodical Offices of Chang'an University There is a wide range of routine skid resistance measurement devices on the market. All of them are measuring the friction force between a rubber wheel and the wetted road surface. Common to all of them is that they are relatively complex and costly because generally a truck carrying a large water tank is needed to wet the surface with a defined water layer. Because of the limited amount of water they can carry they are limited in range. Besides that the measurement is depending on factors like water film thickness, temperature, measurement speed, rubber aging, rubber wear and even road evenness and curviness. All of these factors will affect the skid resistance and are difficult to control. We present a concept of contactless skid resistance measurement which is based on optical texture measurement and consists of two components: measurement of the pavement texture by means of an optical measuring system and calculation of the skid resistance based on the measured texture by means of a rubber friction model. The basic assumptions underlying the theoretical approach and the model itself based on the theory of Persson are presented. The concept is applied to a laboratory device called Wehner/Schulze (W/S) machine to prove the theoretical approach. The results are very promising. A strong indication could be provided that skid resistance could be measured without contact in the future.

Application of semi-analytical finite element method coupled with infinite element for analysis of asphalt pavement structural response

Volume 2, Issue 1, February 2015, Pages 48-58
Pengfei Liu | Dawei Wang | Markus Oeser

© 2015 The Authors A specific computational program SAFEM was developed based on semi-analytical finite element (FE) method for analysis of asphalt pavement structural responses under static loads. The reliability and efficiency of this FE program was proved by comparison with the general commercial FE software ABAQUS. In order to further reduce the computational time without decrease of the accuracy, the infinite element was added to this program. The results of the finite-infinite element coupling analysis were compared with those of finite element analysis derived from the verified FE program. The study shows that finite-infinite element coupling analysis has higher reliability and efficiency.

Timetable optimization for single bus line based on hybrid vehicle size model

Volume 2, Issue 3, June 2015, Pages 179-186
Daniel Jian Sun | Daniel Jian Sun | Daniel Jian Sun | Ya Xu | Zhong Ren Peng | Zhong Ren Peng

© 2015 Periodical Offices of Chang & rsquo;an University This study proposes a flexible timetable optimization method based on hybrid vehicle size model to tackle the bus demand fluctuations in transit operation. Three different models for hybrid vehicle, large vehicle and small vehicle are built in this study, respectively. With the operation data of Shanghai Transit Route 55 at peak and off-peak hours, a heuristic algorithm was proposed to solve the problem. The results indicate that the hybrid vehicle size model excels the other two modes both in the total time and total cost. The study verifies the rationality of the strategy of hybrid vehicle size model and highlights the importance of the adaptive vehicle size in dealing with the bus demand fluctuation. The main innovation of the study is that unlike traditional timetables, the arrangement of the scheduling interval and the corresponding bus type or size are both involved in the timetable of hybrid vehicle size bus mode, which will be more effective to solve the problem of passenger demand fluctuation. Findings from this research would provide a new perspective to improve the level of regular bus service.

Evaluation of pedestrian mid-block road crossing behaviour using artificial neural network

Volume 1, Issue 2, April 2014, Pages 111-119
B. Raghuram Kadali | Nivedan Rathi | Vedagiri Perumal

© 2014 Periodical Offices of Chang'an University Pedestrians usually cross the road at mid-block locations in India because of the ease and convenience to reach their destination as compared to intersection locations. It is important to evaluate the pedestrian gap acceptance behavior at mid-block locations because of inadequate vehicular gaps under mixed traffic condition, which translates into the pedestrian road crossing behavior. The present study examines the pedestrian gap acceptance behaviour by employing an artificial neural network (ANN) model for understanding the decision making process of pedestrians, i.e., acceptance or rejection of vehicular gaps at a mid-block location. From the results it has been found that the pedestrian rolling gap, frequency of attempt, vehicular gap size, pedestrian speed change condition and vehicle speed have major role in pedestrian gap acceptance. These results can lead to a better design of pedestrian crossing facilities where adequate gaps are not available in vehicular flow at mid-block crosswalk locations.

Influence of roadway geometric elements on driver behavior when overtaking bicycles on rural roads

Volume 1, Issue 1, February 2014, Pages 28-38
Jeremy R. Chapman | David A. Noyce

© 2014 Periodical Offices of Chang'an University The objective of this research was to determine what influence geometric design elements of roadway may have on driver behavior during the overtaking maneuver. This was part of a larger research effort to eliminate crashes (and the resulting fatalities and injuries) between bicycles and motorized vehicles. The data collection process produced 1151 observations with approximately 40 different independent variables for each data point through direct observation, sensor logging, or derivation from other independent variables. Prior research by the authors developed a means to collect real-time field data through the use of a bicycle-mounted data collection system. The collected data was then used to model lateral clearance distance between vehicles and bicycles. The developed model confirmed field observations that the lateral clearance distance provided by drivers changes with vehicle speed and oncoming vehicle presence. These observations were presented by the authors previously. The model shows that driver behavior can be adjusted by the inclusion, or exclusion, of geometric elements. Evaluating roadways (or roadway designs) based on this model will enable stakeholders to identify those roadway segments where a paved shoulder would prove an effective safety countermeasure. This research will also enable roadway designers to better identify during the design phase those roadway segments that should be constructed with a paved shoulder.

Progress on wheel-rail dynamic performance of railway curve negotiation

Volume 1, Issue 3, June 2014, Pages 209-220
Kaiyun Wang | Chao Huang | Wanming Zhai | Pengfei Liu | Shen Wang

© 2014 Periodical Offices of Chang'an University Recent advances on wheel-rail dynamic performance of curve negotiation are reviewed in this paper. There are four issues, the mechanism and calculation method of curve negotiation, the analysis and assessment of dynamic performance of vehicle, the effect of vehicle parameters on dynamic performance, and the influence of railway parameters on dynamic performance. The promising future development of wheel-rail coupled dynamics theory is analyzed in the research of curve negotiation. The framework and technique matching performance of wheel-rail dynamic interaction on the curved track are put forward for modern railways. In addition, the application of performance matching technique is introduced to the dynamic engineering, in which the wheel load is reduced obviously when the speed of train is raised to 200-250 km/h.

Modelling follow up time at a single-lane roundabout

Volume 1, Issue 2, April 2014, Pages 97-102
Xiaobo Qu | Jin Zhang | Shuaian Wang | Zhiyuan Liu

© 2014 Periodical Offices of Chang'an University The follow up time is an important parameter for estimating the entry capacity of roundabouts. However, its variability and contributing factors have long been ignored in the literatures. In this study, 171 follow up samples and contributing factors (traffic volume, vehicle position, waiting vehicles behind, vehicle type, and drivers’ gender) are collected at a roundabout in Pacific Pines, Australia. It is found that the follow up time is indeed significantly affected by traffic volume, waiting vehicles behind, vehicle type, and drivers’ gender. In order to establish the relationship between the follow up time and its contributing factors, an inverse Gaussian regression model is further developed. This relationship could be applied to estimate the entry capacities by taking into account the variability of follow up samples. According to the model, the traffic volume and vehicle types are the most important contributing factors.

Study on pedestrian crossing behavior at signalized intersections

Volume 1, Issue 2, April 2014, Pages 103-110
Marisamynathan | Vedagiri Perumal

© 2014 Periodical Offices of Chang'an University A clear understanding of pedestrian crossing behavior under mixed traffic conditions is needed for providing necessary infrastructure and also for enhancing pedestrian safety at signalized intersections. This paper attempts to analyze the crossing behavior of pedestrians like crossing speed, compliance with signal, and pedestrian-vehicular interaction under mixed traffic conditions and to identify the influencing factors based on statistical tests. 775 pedestrian samples were observed from three signalized intersections in Mumbai, India for analyzing crossing behaviors and the significant factors affecting traffic signal compliance by pedestrians were identified by conducting Pearson's correlation coefficient test, ANOVA test, and Student t test. Factors influencing pedestrian crossing speed had been studied and a design crossing speed had been determined for old and adult pedestrians at 0.95 m/s and 1.12 m/s respectively. Logistic regression models had been developed in which the odds of pedestrian violation and interactions were modeled and verified. This study can help researchers and practitioners to understand pedestrian crossing behavior at signalized intersections and develop pedestrian delay models under mixed traffic conditions.

Dynamic response of concrete pavement structure with asphalt isolating layer under moving loads

Volume 1, Issue 6, December 2014, Pages 439-447
Jianmin Wu | Jiaping Liang | Sanjeev Adhikari

© 2014 Periodical Offices of Chang'an University A three-dimensional finite element model (3D FEM) is built using ABAQUS to analyze the dynamic response of a concrete pavement structure with an asphalt isolating layer under moving loads. The 3D model is prepared and validated in the state of no asphalt isolating layer. Stress and deflection at the critical load position are calculated by changing thickness, modulus of isolating layer and the combination between the isolating layer and concrete slab. Analysis result shows that the stress and deflection of the concrete slab increase with the increase of thickness. The stress and deflection of the concrete slab decrease with the increase of combination between the isolating layer and concrete slab. The influence of changing the isolating layer modulus to the stress and deflection of the concrete slab is not significant. From the results, asphalt isolating layer design is suggested in concrete pavement.

Distracted walking: Examining the extent to pedestrian safety problems

Volume 2, Issue 5, October 2015, Pages 327-337
Judith Mwakalonge | Saidi Siuhi | Jamario White

© 2015 Periodical Offices of Chang & rsquo;an University Pedestrians, much like drivers, have always been engaged in multi-tasking like using hand-held devices, listening to music, snacking, or reading while walking. The effects are similar to those experienced by distracted drivers. However, distracted walking has not received similar policies and effective interventions as distracted driving to improve pedestrian safety. This study reviewed the state-of-practice on policies, campaigns, available data, identified research needs, and opportunities pertaining to distracted walking. A comprehensive review of literature revealed that some of the agencies/organizations disseminate useful information about certain distracting activities that pedestrians should avoid while walking to improve their safety. Various walking safety rules/tips have been given, such as not wearing headphones or talking on a cell phone while crossing a street, keeping the volume down, hanging up the phone while walking, being aware of traffic, and avoiding distractions like walking with texting. The majority of the past observational-based and experimental-based studies reviewed in this study on distracted walking is in agreement that there is a positive correlation between distraction and unsafe walking behavior. However, limitations of the existing crash data suggest that distracted walking may not be a severe threat to the public health. Current pedestrian crash data provide insufficient information for researchers to examine the extent to which distracted walking causes and/or contributes to actual pedestrian safety problems.

Sensitivity analysis of project level MOVES running emission rates for light and heavy duty vehicles

Volume 1, Issue 2, April 2014, Pages 81-96
Zhuo Yao | Heng Wei | Harikishan Perugu | Hao Liu | Zhixia Li

© 2014 Periodical Offices of Chang'an University In order to understand how the uncertainties in the output can be apportioned to different sources of uncertainties in its inputs, it is critical to investigate the sensitivity of MOVES model. The MOVES model sensitivity for regional level has been well studied. However, the uncertainty analysis for project level running emissions has not been well understood. In this research, the MOVES model project level sensitivity tests on running emissions were conducted thru the analysis of vehicle specific power (VSP), scaled tractive power (STP), and MOVES emission rates versus speed curves. This study tested the speed, acceleration, and grade-three most critical variables for vehicle specific power for light duty vehicles and scaled tractive power for heavy duty vehicles. For the testing of STP, four regulatory classes of heavy duty vehicles including light heavy duty (LHD), medium heavy duty (MHD), heavy heavy duty (HHD) and bus were selected. MOVES project running emission rates were also tested for CO, PM2. 5, NOxand VOC versus the operating speeds. A Latin Hypercube (LH) sampling based on method for estimation of the “Sobal” sensitivity indices shows that the speed is the most critical variable among the three inputs for both VSP and STP. Acceleration and grades show lower response to the main effects and sensitivity indices. MOVES emission rates versus speeds curves for light duty vehicles show that highest emission occurs at lower speed range. No significant differences on emission rates among the regulatory classes of heavy duty vehicles are identified.

Sensitivity analysis of longitudinal cracking on asphalt pavement using MEPDG in permafrost region

Volume 2, Issue 1, February 2015, Pages 40-47
Chen Zhang | Hainian Wang | Zhanping You | Biao Ma

© 2015 Periodical Offices of Chang'an University Longitudinal cracking is one of the most important distresses of asphalt pavement in permafrost regions. The sensitivity analysis of design parameters for asphalt pavement can be used to study the influence of every parameter on longitudinal cracking, which can help optimizing the design of the pavement structure. In this study, 20 test sections of Qinghai–Tibet Highway were selected to conduct the sensitivity analysis of longitudinal cracking on material parameter based on Mechanistic-Empirical Pavement Design Guide (MEPDG) and single factorial sensitivity analysis method. Some computer aided engineering (CAE) simulation techniques, such as the Latin hypercube sampling (LHS) technique and the multiple regression analysis are used as auxiliary means. Finally, the sensitivity spectrum of material parameter on longitudinal cracking was established. The result shows the multiple regression analysis can be used to determine the remarkable influence factor more efficiently and to process the qualitative analysis when applying the MEPDG software in sensitivity analysis of longitudinal cracking in permafrost regions. The effect weights of the three parameters on longitudinal cracking in descending order are air void, effective binder content and PG grade. The influence of air void on top layer is bigger than that on middle layer and bottom layer. The influence of effective asphalt content on top layer is bigger than that on middle layer and bottom layer, and the influence of bottom layer is slightly bigger than middle layer. The accumulated value of longitudinal cracking on middle layer and bottom layer in the design life would begin to increase when the design temperature of PG grade increased.

Graded-information feedback strategy in two-route systems under ATIS

Volume 1, Issue 2, April 2014, Pages 138-145
Jianqiang Wang | Huimin Niu

© 2014 Periodical Offices of Chang'an University In consideration of the constraint of the advanced traveler information systems (ATIS) detecting accuracy and the time delay of information feedback systems, a novel approach named graded- information feedback strategy is proposed and applied into a two-route scenario. The approach adopts the fuzzy C-means clustering algorithm to classify road traffic conditions based on flux, mean velocity, and density. Then, each cluster centre is fixed on. Furthermore, real-time traffic conditions on each route could be judged by the preceding cluster centers. Results of judgment would be displayed on variable message signs to guide the successors at the entrance to make reasonable route-choices. Meanwhile, a cellular automaton model is adopted to investigate the correlation between efficiency of two- route systems, number of clustering, and travelers’ route choice behavior. Compared with the conventional strategies, the simulation shows that the innovative information feedback strategy can evidently improve utilization efficiency of road networks.

Characterization of pavement texture by means of height difference correlation and relation to wet skid resistance

Volume 2, Issue 2, April 2015, Pages 59-67
Stefan Torbruegge | Burkhard Wies

© 2015 Periodical Offices of Chang & rsquo;an University Driving safety is of utmost importance in the automobile industry and is acknowledged by the introduction of the tire wet grip index as part of the EU tire label. The rubber pavement interaction is determined by the viscoelastic properties of the rubber as well as by the pavement texture. Nowadays available optical surface profiling instruments allow for a detailed measurement of surface roughness covering several length scales. This enables the validation of a mathematical statistical description of pavement texture within the framework of self-affine surfaces and hence provides a holistic characterization of surface roughness covering several length scales within a few characteristic parameters. We deduce within this article the correlation between classical surface roughness parameters and the parameter set of self-affine surfaces. These parameters allow for a detailed understanding of the relationship between pavement texture and its wet skid resistance. We present wet skid resistance measurements with the British pendulum and a linear friction tester device on different pavement textures. We demonstrate that the so-called estimated texture depth does not correlate to the surface skid resistance measured with the British pendulum. Finally, we deduce a dependency of wet skid resistance on pavement texture which is supported by current models for hysteresis friction.

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