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.

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.

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).

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.

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.

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.