The construction cost and crash cost of the highway are contradictory, but there is an optimal balance between them. This study focused on the best balance point by microadjusting the highway alignment design using the optimization theory. A multiobjective optimization method was proposed to optimize the highway horizontal alignment design considering the economy and safety. The optimization model includes three main objective functions which are the economic objective function, safety objective function, and position constraint objective function. Constraints were established for the optimization model following the corresponding specifications, such as constraints for the three elements in the design unit, continuous constraints for adjacent alignments, constraints for the location of horizontal alignment, and constraints for speed coordination. Two scenarios were considered to verify the effect of the optimization model. One scenario considered the constraints of the intermediate control points, and the other does not. In addition, two cases were analyzed. One is optimization for a horizontal alignment design unit. Another one is for a highway segment including four design units. The parallel genetic algorithm was used to solve the optimization model. Case study results indicate that the optimization model could help to improve the safety and economics of highways. In addition, the proposed optimization model could reduce much more redundant debugging work for the designer and reduce the influence of the designer’s subjectivity.

In this paper, a kind of underground passage automated freight transport system based on the autonomous dual-mode container truck is proposed, and the overall structure of the automated freight transport system, the allocation of the transportation equipment, the comprehensive design of underground passage, the comprehensive analysis of transportation organization, the reasonable layout of the freight transport terminal, and the design of connection with the overall operation of the port are studied. Taking the connection passage between the central operation area and the eastern operation area of Yantian Port under planning and construction as an example, this paper expounds the application of the underground automatic freight transport system design method in the underground container logistics system within the port area. Based on the current situation and the long-term planning requirements of Yantian Port, the overall route of the connection passage between the central operation area and the eastern operation area is studied; the dual mode transportation organization model based on the combination of autonomous driving and manned driving is designed, and the manned driving mode shall be adopted within the operation area. In the connecting tunnel, there is the interference-free, fully-enclosed, line-fixed, and no man’s land application scenario, and the autonomous driving mode shall be adopted. The corresponding ground switching area is proposed to match the dual-mode transportation system of the autonomous dual-mode truck; such switching area is composed of the mode switching area, truck storage area, and driver rest and management room. Compared with the traditional tunnels, the autonomous freight transport passage has obvious advantages in saving project cost and improving transport efficiency.

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Under the urban road system, the most frequent locations for traffic accidents are concentrated at road intersections, where left-turning traffic is one of the most direct and important factors causing intersection conflicts. There are relatively few applied models that can effectively explain the trajectory change characteristics and exit lane selection behavior of left-turning vehicles, making it more difficult to achieve accurate analysis and prediction of intersection vehicle conflict behavior. This study extracted trajectories of left-turning vehicles at the intersection based on the video captured by the UAV, and a vehicle left-turning trajectory model was proposed based on the curvature change of the vehicle trajectory. Also, based on the geometric parameters of the intersection and video data, a vehicle exits lane selection model with intersection turning angle, vehicle type, vehicle position at the entrance lane, vehicle speed and following clearance, and front car position at the exit lane as variables was developed using random utility theory. The results show that the left-turn trajectory could be fitted with a flat curve, and the curvature of the trajectory varies with the aspect ratio of the intersection in a quadratic parabolic relationship. The left-turn trajectory model established in the paper could effectively characterize the driving trajectory of left-turning vehicles at different intersections. The exit lane selection model could effectively predict the distribution of left-turning vehicles in the exit lane position, as the turning angle, vehicle position at the entrance lane and vehicle speed have a significant effect on the choice of exit lane for left-turning vehicles.

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