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In this paper, an iterative approximate dynamic programming algorithm is proposed for solving the approximate optimal tracking control problem for a class of nonlinear discrete-time switched systems. Firstly, the optimal tracking problem is converted into designing an optimal regulator for the tracking error dynamics. And then, the iterative approximate dynamic programming algorithm is proposed to obtain the approximate solution of the Hamilton-Jacobi-Bellman (HJB) equation. Next, two neural networks are used to approximate the iterative cost function and the iterative control law, respectively. Finally, simulation results are given to verify the effectiveness of the proposed algorithm.

Interactions between bicycles and cars have begun to attract increasing attention. This paper aims to investigate network-level car-bicycle interactions by quantifying the impact of bicycle traffic on empirical macroscopic fundamental diagrams (MFDs). First, the stratified re-sampling method is used to analyze the impact of bicycle-related facilities on network capacity and critical density. Then, the trapezoidal MFD function is applied to investigate the relationship between network bicycle flow and upper-bound MFD. The results show that car-bicycle mixed roads can have a negative marginal effect on network capacity and critical density, regardless of separation and road type. However, difference of capacity reduction in networks with various percentages of car-only roads is not substantial. To reduce car-bicycle interactions at the network level, it is more efficient to improve bicycle network capacity and build more exclusive bicycle facilities than restrict roads for bicycle users in central areas. Based on these results, various traffic management strategies can be applied, such as adjusting the share of car-only roads, changing separation type, redistributing road space among different modes and extending bicycle priority in certain areas., Arbeitsberichte Verkehrs- und Raumplanung, 1456

Accessibility for non-motorized traffic is an important topic in the transportation. To obtain the measures of bicycle accessibility, we estimated the impedance function for different purposes using the Shanghai dock-less bicycle-sharing data. In specific, as the bicycling data have no trip purpose information, the information was imputed by a Dirichlet-multinomial regression topic model (DMR), which could consider the arriving time and drop-off location simultaneously. The imputed results were validated by displaying the trip purposes on the visualized map in Shanghai central area. Then the impedance functions of the bicycling accessibility model were further estimated for the trips with different purposes based on the trips’ distance and duration. We found the descriptive values of the real trips and parameters of the impedance functions for different trip purposes were different. In addition, almost 90% of trips were less than 30 minutes and 5 kilometers. Finally, two cases of bicycling accessibility with two different purposes (restaurant and hospital), were illustrated in the central area of Shanghai based on the estimated impedance function. This study demonstrates the feasibility of combining bicycle-sharing GPS data and the DMR model to estimate the bicycle accessibility. Moreover, the estimated models for different purposes can benefit for urban planning and development, such as bicycle-based transit-oriented development and land use-transportation planning evaluation., Arbeitsberichte Verkehrs- und Raumplanung, 1377

To alleviate traffic congestion in the city center, many cities in China restrict non-local vehicles using expressways or entering the central area during the morning peak and the evening peak, such as Shanghai, Beijing and Shenzhen. In Shanghai, the non-local plate vehicle restriction policy started to be implemented in 2002, which banned vehicles without local plates using elevated highways in the central area from 7:30 am to 9:30 am and from 4:30 pm to 6:30 pm. This restriction was firstly tightened in 2015 and further tightened in 2016, with longer restricted hours and expanded banned expressways. However, no relevant research has been found to empirically evaluate these policies from the perspective of macroscopic traffic performance. In this study, the macroscopic fundamental diagram (MFD) approach is used to evaluate the performances of Shanghai’s macroscopic traffic under the three different restriction policies. The macroscopic effects of the restriction policy on the restricted expressways are compared with the surface roads without any restrictions. Moreover, the time-varying characteristics of macroscopic traffic performance, e.g., hysteresis loop, during the morning peak and the evening peak, are further investigated in this study.