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Liu D.-B.,Traffic Management Research Institute
Jiaotong Yunshu Xitong Gongcheng Yu Xinxi/Journal of Transportation Systems Engineering and Information Technology | Year: 2013

With the goal of developing a resource-efficient traffic environment, this paper puts forward traffic performance evaluation system for highway ETC systems based on the principle of scientific, systematic and operability. It consideres the views of investors, managers and users and integrates the elements including vehicle travel speed, traffic delay, highway capacity, traffic safety, noise pollution and gas emission. Through a combined methodology of qualitative and quantitative research, it develops a system of quantified criteria for evaluation. Furthermore, it conducts extra-performance analyses on the ETC construction projects under various traffic flow conditions by applying the data envelopment analysis (DEA). This paper gives the ultra-efficient quantized value of the ETC construction projects under different traffic conditions as an example. It also works out the relative ratio of the effective value corresponding to different traffic to find out the root causes of low efficiency and to propose corresponding measures. Source


Liu D.,Traffic Management Research Institute
ICTIS 2013: Improving Multimodal Transportation Systems - Information, Safety, and Integration - Proceedings of the 2nd International Conference on Transportation Information and Safety | Year: 2013

Although all types of road users are at risk of being injured or killed in a road traffic crash, there are notable differences in fatality rates between different road user groups. The "vulnerable" road users (VRUs), such as pedestrians and two-wheeler users, are at greater risk than vehicle occupants. In particular, with the popular use of the electric bicycle, the vulnerable road users involved in traffic accidents (VRUITAs) become more frequent in China. Therefore, the characteristics of VRUITAs were first explored from accident data. The crash composition and other measurements were analyzed in this study. The reasons for VRUITAs in China were then compared with those in developed countries from the aspects of legislation, driving training and traffic management. The results indicate that the vulnerable road users in China were more likely to break the traffic rules and take risky behavior. Several counter measures derived from developed countries were finally discussed to be further applied in China to reduce the VRUITAs. © 2013 American Society of Civil Engineers. Source


Chen Y.-K.,Hefei University of Technology | Chen Y.-K.,Traffic Management Research Institute | He J.,Nanjing Southeast University | King M.,Queensland University of Technology | And 2 more authors.
Journal of Central South University | Year: 2013

Two simple and effective control strategies for a multi-axle heavy truck, modified skyhook damping (MSD) control and proportional-integration-derivative (PID) control, were implemented into functional virtual prototype (FVP) model and compared in terms of road friendliness and ride comfort. A four-axle heavy truck-road coupling system model was established using FVP technology and validated through a ride comfort test. Then appropriate passive air suspensions were chosen to replace the rear tandem suspensions of the original truck model for preliminary optimization. The mechanical properties and time lag of dampers were taken into account in simulations of MSD and PID semi-active dampers implemented using MATLAB/Simulink. Through co-simulations with Adams and MATLAB, the effects of semi-active MSD and PID control were analyzed and compared, and control parameters which afforded the best comprehensive performance for each control strategy were chosen. Simulation results indicate that compared with the passive air suspension truck, semi-active MSD control improves both ride comfort and road-friendliness markedly, with optimization ratios of RMS vertical acceleration and RMS tyre force ranging from 10.1% to 44.8%. However, semi-active PID control only reduces vertical vibration of the driver's seat by 11.1%, 11.1% and 10.9% on A, B and C level roads respectively. Both strategies are robust to the variation of road level. © 2013 Central South University Press and Springer-Verlag Berlin Heidelberg. Source


Zhan J.,Iowa State University | Vaswani N.,Iowa State University | Qiu C.,Traffic Management Research Institute
IEEE International Symposium on Information Theory - Proceedings | Year: 2014

Online or recursive robust PCA can be posed as a problem of recovering a sparse vector, St, and a dense vector, Lt, which lies in a slowly changing low-dimensional subspace, from Mt S t+Lt on-the-fly as new data comes in. For initialization, it is assumed that an accurate knowledge of the subspace in which L0 lies is available. In recent works, Qiu et al proposed and analyzed a novel solution to this problem called recursive projected compressed sensing or ReProCS. In this work, we relax one limiting assumption of Qiu et al's result. Their work required that the Lt's be mutually independent over time. However this is not a practical assumption, e.g., in the video application, Lt is the background image sequence and one would expect it to be correlated over time. In this work we relax this and allow the Lt's to follow an autoregressive model. We are able to show that under mild assumptions and under a denseness assumption on the unestimated part of the changed subspace, with high probability (w.h.p.), ReProCS can exactly recover the support set of St at all times; the reconstruction errors of both St and Lt are upper bounded by a time invariant and small value; and the subspace recovery error decays to a small value within a finite delay of a subspace change time. © 2014 IEEE. Source


Zhang H.,Wuhan University of Technology | Zhang H.,Engineering Research Center for Transportation Safety | Yan X.,Wuhan University of Technology | Yan X.,Engineering Research Center for Transportation Safety | And 4 more authors.
Jiangsu Daxue Xuebao (Ziran Kexue Ban)/Journal of Jiangsu University (Natural Science Edition) | Year: 2011

To evaluate the effect of driver subjective cognition of highway safety level on vehicle speed, the real vehicle experiment was designed. Fifty drivers were invited to determine the weight of the highway parameters which is related to driving safety. Based on the subjective evaluation of 719 drivers on highway safety level of horizontal, vertical alignments and sight distance, the fuzzy comprehensive model of safety level was established, and the driving speeds at different section of evaluated highway were collected. The results show that the vehicle speed on each road section is closely related with the subjective cognition of road safety level which is based on the fuzzy comprehensive evaluation model. Considering the insecurity of next approach road section, the driver will decrease the speed to ensure safety. The evaluation model is effective for simulating the process that driver chooses safe speed based on safety degree of highway. Source

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