As the number of motor vehicles in China’s cities continues to increase, the imbalance between the capacity that existing urban roads have for construction and the demand for motor vehicles is becoming increasingly evident. Indeed, the design of the intersection U-turn scheme has garnered significant attention from researchers. However, as the number of vehicles requiring U-turns increases, the traditional U-turn in the median or U-turn at the intersection fails to meet the timely demand for U-turns. In such cases, vehicles needing to make U-turns are required to queue first. As the queue length grows, it ultimately impacts the operational efficiency of the intersection. To optimize the imbalance between supply and demand at these intersections and promote the sustainable development of intersections, an innovative form of U-turn organization called the Parallel U-turn has been developed. In the engineering practice of reconstructing existing intersections or constructing new ones, it is crucial to investigate the compatibility between various U-turn design forms and traffic volumes. This exploration helps ensure that the chosen U-turn design effectively accommodates the specific traffic demands at the intersection. Therefore, in this paper, a typical intersection in Xi’an was chosen as the study intersection to investigate traffic data. The researchers calibrated and simulated four U-turn organization schemes using VISSIM microsimulation software. The four schemes included a traditional U-turn at the intersection, a Parallel U-turn at the intersection, a traditional U-turn in the median, and a Parallel U-turn in the median. Then, the researchers used the entropy-weighted TOPSIS method (EWTM) to evaluate the compatibility of each U-turn organization scheme for different traffic combinations. This assessment was conducted based on three criteria: operational efficiency, environmental protection, and safety performance. The results of this study indicate that the Parallel U-turn design is advantageous for the XiaoZhai intersection in Xi’an, China, under specific traffic conditions. When the traffic volume at the intersection exceeds 5940 vehicles per hour but remains below the intersection’s maximum capacity, implementing the Parallel U-turn design could yield positive outcomes in terms of operational efficiency, safety performance, and a reduction in intersection pollution. In summary, by enhancing operational efficiency, safety, and environmental impact, the Parallel U-turn design promotes the overall performance and sustainability of the XiaoZhai intersection and the transportation system in Xi’an, China.

Interchanges are the key nodes of the freeway. Due to the existence of weaving behavior, the traffic flow situation is more complicated for small spacing interchanges. Continuous auxiliary lanes are usually used to connect the entrance and exit to form a compound interchange to reduce the interference of weaving behavior. However, when it comes to the design of auxiliary lane forms, China lacks relevant design specifications and research in this area. As a result, there often exists the phenomenon of mismatch between the design form and the traffic volume. In this paper, we took a compound interchange in Xi’an as the research object, proposing four auxiliary lane design schemes and using VISSIM (2022 student) software to establish the simulation model. Additionally, various traffic conditions were simulated through sensitivity analysis. Finally, using the factor analysis method and entropy method, we comprehensively assigned weights to the indexes. By obtaining the weighted scores for various schemes, it became possible to determine the applicability of each scheme under different traffic conditions. The results indicate that the gradient auxiliary lane can be applied to most traffic conditions and has a smaller land occupation than the traditional design, which is an optimization and improvement for the traditional design form.

The deceleration lane is an important part of the freeway, and the rationality of its design parameters affects the exit accident rate. The traditional calculation method is based on the design of speed and vehicle parameters using deterministic methods, ignoring the randomness of the driver’s deceleration behavior. It is necessary to calculate the length and slope of the deceleration lane in detail according to the deceleration characteristics of the driver in the deceleration section by using the uncertainty method. This paper describes a study on the maximum longitudinal slope of the downhill section of the deceleration lane, where the safety of diverging vehicles is unfavorable. By collecting deceleration lane data from interchanges around Xi’an (Shaanxi Province, China, Coordinates: 108.95, 34.27) and analyzing the deceleration characteristics of vehicles, we propose a new deceleration model. In addition, the limit-state functions of the length and slope of the deceleration lane have been established based on the reliability theory. Finally, according to the deceleration characteristics, we determined the probability distribution of key parameters in the vehicle deceleration process. We used the Monte Carlo Simulation (MCS) and the Improved First-Order Second Moments (IFOSM) calculation model to calculate the length and slope of the deceleration lane, respectively. Finally, we propose the recommended values for the length and slope of the deceleration lane. The results of the study showed that: (1) The movement process of the vehicle on the deceleration section adopts a uniform deceleration, and the truck and the car start to decelerate from the starting of the taper section and diverging point, respectively. (2) The control vehicle in the deceleration lane calculation model is the compact car. (3) The reliability theory has good applicability in calculating freeway alignment indexes. It fully considers the probability of driver deceleration behavior in the calculation model, which provides a more suitable method for the calculation of deceleration lane indexes.

Due to the increasing demand for transportation, road renovation is inevitable, and the emergence of work zones has become the most common problem in traffic control. There are many research results on the impact of work zones on traffic operation, but most of them focus on various capacity theoretical models or traffic flow control strategies and are mostly concentrated in highway work areas and urban road subway construction work areas. The location of these work zones is often unable to be changed and is mostly considered reasonable. At present, there is still a gap in selecting and evaluating the location of the work zone. Therefore, this article studied a bidirectional six-lane intersection in Xi’an and investigated the situation of traffic flow distortion caused by the setting of work zones at the intersection. Two different positions and forms of work zones were designed for evaluation and analysis. Firstly, we used VISSIM (2022 student) to simulate the original and proposed work zone road-occupation schemes and analyzed six indicators. Finally, in order to determine the optimal work zone locations under different traffic situations, we applied the entropy weight method (EWM) to assign weights to multiple indicators, thereby achieving a comprehensive assessment of various schemes. The results showed that the highest improvement level among the six indicators was 50.2%, and different schemes adapted to different traffic situations. However, occupying two lanes of the median opposite the exit lane performed better under high traffic volume. Occupying the median and lanes on both sides of the median is suitable for low traffic volume. Occupying two lanes of the entrance lane and using the opposite lane as the left-turn entrance lane is suitable for situations with high traffic volume in the opposite lane.