Zhang Chen

As one of the effective measures of intelligent traffic control, on-ramp metering is often used to improve the traffic efficiency of expressways. Existing on-ramp metering research mainly discusses expressways with right-side on-ramps. However, for underground expressway systems (UESs), left-side on-ramps are frequently adopted to reduce the ground space occupied by ramp construction. Since traffic entering from the left and right sides of the mainline may have different traffic characteristics, on-ramp metering for UESs with left-side on-ramps should be explored specifically. This study examines the impacts of left-side on-ramps on the traffic safety and efficiency of UESs and proposes an effective on-ramp metering strategy. Firstly, using field data, traffic flow fundamental diagrams and speed dispersion are discussed to explore the traffic flow characteristics of the “left-in” UES. The results show that the capacity and critical occupancy are both reduced in left-side on-ramp compared to right-side on-ramp expressways. Meanwhile, the speed dispersion is higher in left-side on-ramp UESs, which means a higher accident risk. Based on this, considering traffic safety and efficiency, a novel two-parameter left-side on-ramp metering strategy for UESs is proposed, in which occupancy and speed are used as the control indicators simultaneously. Additionally, the mechanism of the metering strategy is explained. Finally, the proposed on-ramp metering strategy is simulated on a real UES. The results demonstrate the advantages of the proposed two-parameter on-ramp metering strategy for improving the traffic safety and efficiency of UESs.

We study transportation network design with stochastic demands and emergency vehicle (EV) lanes. Different from previous studies, this paper considers two groups of users, auto and EV travelers, whose road access rights are differentiated in the network, and addresses the value of incorporating inverse-direction lanes in network design. We formulate the problem as a bilevel optimization model, where the upper-level model aims to determine the optimal design of EV lanes and the lower-level model uses the user equilibrium principle to forecast the route choice of road users. A simulation-based genetic algorithm is proposed to solve the model. With numerical experiments, we demonstrate the value of deploying inverse-direction EV lanes and the computational efficiency of the proposed algorithm. We reach an intriguing finding that both regular and EV lane users can benefit from building EV lanes.

Tire-road noise contains two aspects, one is aerodynamic noise, another is vibration noise that the traffic noise affects a large proportion of it. It is obvious that reduction of vibration noise can greatly improve the quality of sound environment in town. The primary task of vibration noise reduction study is to get clear on the generation mechanism of driving vibration noise. According to previous researches, the contact conditions between tire and road surface have a significant effect on driving vibration noise. Especially, there must be a link, having not been rigorously studied, between the tire-road contact pressure and vibration noise. Based on the above, the relationship between driving vibration noise and tire-road contact pressure is established in this paper. Through field experiments, it proves that the driving vibration noise of micro-surface is higher than that of SMA-10 (stone matrix asphalt). Meanwhile, the movement progresses of wheel on these two different pavement surfaces and the contact pressure are simulated via DEM (discrete element model), which shows that the volatility of tire-road contact pressure of micro-surface is greater than that of SMA-10. Both the field experiment and DEM demonstrate that the higher volatility of tire-road contact pressure leads the higher driving vibration noise, which can serve as the theoretical foundation of follow-up study.

Road section division is a prerequisite for pavement management and maintenance. The existing research mostly divides road sections arbitrarily without considering the significance of each influencing element. This work presents an improved ordinal cluster division method. The weight of each maintenance factor including equivalent standard axle loadings (ESALs), pavement thickness, pavement roughness, and pavement damage condition is determined by the fuzzy analytic hierarchy process (FAHP) approach. Based on the weight system, the maintenance section is divided utilizing ordinal clustering method. It is solved by recursion formula of dynamic programming with objection to minimize the sum of internal variation of all sections. A numerical case study of the G6 highway was conducted, which demonstrates the effectiveness and efficiency of the proposed method.

Surface characteristics of asphalt pavement have significant impacts on road noise. However, the quantitative relationship between them is not completely clarified. The objective of this paper is to quantify the effect of asphalt pavement surface characteristics on road noise. Firstly, based on acoustics theory, we determined the pavement roughness (IRI) and texture depth (TD) as the factors affecting road noise. Secondly, we conducted a series of field tests, collecting the road noise inside and outside the automobile and measuring the IRI and TD. Finally, we statistically obtained the relationships among interior vehicle noise and exterior vehicle noise, the IRI and ID of the pavement. The result shows that road noise, neither inside nor outside the vehicle, is significant to the TD. Interior vehicle noise is linearly related to the IRI, which rises with the increase of IRI. In addition, exterior vehicle noise can be considered to have a quadric relationship with ln(IRI · TD).

In order to realize the intelligence of a transportation infrastructure management system (TIMS), deterministic models are built according regressive methods, and the pavement performance model is a classic, using the Bayesian approach, which introduced a prior distribution to describe the related information of initial parameters. The new collected data reviewed a sample of the population, then according to the prior distribution and the sample, deduced a posterior distribution that was used to update model parameters. In the next stage of the model updating process, the deduced posterior distribution was a prior distribution and repeated the above process, and model parameters were updated consistently. This Bayesian approach was applied to the case of parameter updating of pavement performance prediction, and it was shown to be a mathematically valid methodology to deal with the problem of the parameter updating. This approach is easy to program, which can be used to realize intelligence of TIMS.

Asphalt overlay on old cement concrete pavement means overlaying an asphalt concrete layer on the old cement concrete pavement to transform the old road. In this paper, a variety of factors that affect pavement comprehensive evaluation were analyzed and summarized to build a comprehensive evaluation system specific for asphalt overlay on old cement concrete pavement. The evaluation system contains a level one indicator, four level two indicators, and several level three indicators.

With the rapid development of road construction, the contradiction between urgent conservation needs and limited conservation funds is becoming more and more prominent. The traditional conservation management model is gradually replaced by the development and application of pavement management system. Relying on the requirement of the road management department of Suzhou, the architecture of Network-level Decision Support System for Urban Road (NDSSUR) was constructed first. Then, a detailed analysis of the most important three parts of the system - performance evaluation, maintenance decision and performance prediction - were carried on. Finally, based on the local dynamic detection data, NDSSUR was applied to evaluate pavement performance, suggest large and medium repair, and do a long-term planning for five years within the urban areas of Suzhou. Results from the program fit the actual condition of the road well.

Recently, with the increase in traffic accidents, more and more attention has been paid to road safety. Traffic ergonomics is the focus on improving the coordination among people, vehicles, and road environments from the angle of traffic participants based on ergonomics. In this paper, by the theory and method of traffic ergonomics, a variety of factors that affect highway safety were analyzed and summarized to establish a highway safety evaluation system based on traffic ergonomics. The evaluation system contains a level one indicator and four level two indicators, and there is a summary of the contents for each of the level two indicators. Finally, an accident-prone segment of Badaling Expressway was taken for example. There were analyses of reasons for accidents and measures for improvement based on the highway safety evaluation system.

Preventive maintenance is a new concept which differs from traditional ideas, roads won't be repaired until damaged. Novachip is a type of preventive maintenance measure. The purpose of this study was to investigate the effect of Novachip applied as a preventive maintenance measure for pavement performance. Based on years of RQI (Riding Quality Index) of Yixian Elevated in Shanghai, the following was accomplished: first, the non-applicability of traditional pavement performance decay model for Novachip was demonstrated by a regression analysis of Matlab, secondly, a new performance decay equation for Novachip was proposed along with a prediction life, finally the superior performance of Novachip used in preventive maintenance was explained by a cost-effect contrast during the entire analysis period. These outcomes will play an important role for the promotion and application of Novachip.