Simulation research on collisions between highway corrugated beam guardrails and vehicles based on LS-DYNA

To explore the safety of highway traffic operations,the vehicle state and guardrail deformation during highway guardrail collisions are simulated and analyzed.The vehicle-guardrail collision is simulated by finite element software such as LS-DYNA and HyperMesh.The vehicle speed settings are 60,80,100 and 120 km/h,and the collision angles are 5°,10°,15°and 20°.The guardrail deformation,vehicle acceleration and energy changes under different collision speeds and angles are studied.The research results show that at the same collision speed,an increase in the collision angle causes more serious damage to the vehicle,a greater transverse displacement of the guardrail,and a greater range of car acceleration fluctuations.When the collision angle is the same,an increase in the collision speed causes greater lateral displacement of the guardrail,a greater vehicle acceleration fluctuation range,and more serious vehicle damage.The results of the study can provide a reference for demonstrating highway guardrail safety.

Quantifying the Indirect Benefits of Transport Infrastructures and Value Capture Ways in Transportation

Urban transportation is closely related to land use. The changes of transportation cost and accessibility have a direct impact on land use and land prices. Land exploitation and land use play a role of redistributing traffic flow in the urban districts. Real property values are regarded as a sole comprehensive index representing all the benefits generated by transport investment. We have applied the theory of time value on transportation to land price model to evaluate the increased value of real estate resulting from improved accessibility. Agency responsible for the development of urban transport infrastructure can capture part of the financial benefit gained by real estate development through a variety of value capture. This enables us to transfer indirect benefit of transport infrastructure construction to transport enterprise and achieve a benign cycle between urban transport investment and land exploitation.

The Joint Control of Variable Speed and On-Ramp Metering for Urban Expressway

The traffic performance of urban expressway is subject to non-recurring and recurring events, which may cause heavy congestion and vehicles long queuing on ramps. The low performance may bring more traffic delay to the whole network of urban road. This paper presents a new method, the joint control of variable speed control and on-ramp metering, which attempts to improve the level of traffic operations on urban expressway. By analyzing traffic flow on urban expressway, an optimum control strategy of variable speed and on-ramp metering is established in the paper.

An integrated approach for dynamic traffic routing and ramp metering using sliding mode control

The problem of designing integrated traffic control strategies for highway networks with the use of route guidance, ramp metering is considered. The highway network is simulated using a first order macroscopic model called LWR model which is a mathematical traffic flow model that formulates the relationships among traffic flow characteristics in terms of density, flow, and mean speed of the traffic stream. An integrated control algorithm is designed to solve the proposed problem, based on the inverse control technique and variable structure control（super twisting sliding mode）. Three case studies have been tested in the presence of an on-ramp at each alternate route and where there is a capacity constraint in the network. In the first case study, there is no capacity constraint at either upstream or downstream of the alternate routes and the function of the proposed algorithm is only to balance the traffic flow on the alternate routes. In the second case study, there is capacity constraint at downstream of alternate routes. The proposed algorithm aims to avoid congestion on the main road and balance the traffic flow on the alternate routes. In the last case study, there is capacity constraint at upstream of alternate routes. The objective of proposed algorithm is to avoid congestion on the main road and to balance the traffic flow on the alternate routes. The obtained results show that the proposed algorithms can establish user equilibrium between two alternate routes even when the on-ramps, located at alternate routes, have different traffic demands.

Urban road area recognition in ITS based on mean shift method

A color-based visual technique is described based on the mean shift image segmentation method providing relevant information for robust localization of the visible road area in Urban Intelligent Transportation System (U-ITS). The traffic image sequences are firstly trained to extract the background and then segmented into separated parts by the mean shift method as initialization, regions with the number of pixels not less than a threshold and with more uniform surfaces with the 'same' color compared to their environment are filtered as recognized road area. The algorithm given in this paper can present road area recognition with arbitrary shapes, which is fit for unstructured road applications in urban cities very well.