Abstract
Congestion has become a significant issue in recent years and has greatly affected the efficiency of urban traffic operation. Random and disorderly lane-changing behavior greatly reduces traffic capacity and safety. This paper is mainly concerned with the relationship of lane-changing spacing intervals provided by off-ramp facilities and traffic flow conditions. Through field investigations in Beijing, several typical lane-changing behaviors at off-ramp areas are analyzed. By using field traffic data and actual road geometry parameters, VISSIM-based micro-behavior simulations at off-ramp areas are implemented to obtain traffic flow conditions with different lane-changing spacing intervals and other model parameters, such as traffic volume and ratio of off-ramp vehicles. Then, the numerical relationships between traffic flow state and model parameters can be shown. The results show that with increasing traffic volume and the ratio of off-ramp vehicles, the lane-changing spacing interval required by vehicles should be increased. For the same ratio of off-ramp vehicles, if the traffic volume increases by 100 pcu/h/lane (pcu is a unit to stand for a standard passenger car), the corresponding lane-changing spacing interval should be increased by a spacing of 50–100 m to avoid increasing congestion. Based on the results of this paper, smart lane management can be implemented by optimizing lane-changing spacing intervals and lane-changing behaviors to improve traffic capacity.
Highlights
With the rapid development of society and the economy, cities are enlarged every year, especially in China
To insure the reliability and specificity of the simulation results and to study the impact of lanechanging spacing interval on traffic flow conditions at the off-ramp areas, the following assumptions were made to eliminate the influence of other factors: (1) there was no congestion of the mainline downstream, and (2) there was no congestion of the side road downstream
The traffic flow state based on indexes sectional speed (SS) and travel time (TT) were studied in Scenario II.2 by different combinations of S and Q
Summary
With the rapid development of society and the economy, cities are enlarged every year, especially in China. Lane-changing behaviors in off-ramp areas is a typical mandatory lane-changing behavior, which leads to remarkable influence on the following or adjacent traffic streams, especially for congestion flow. Determining appropriate lane-changing spacing intervals for off-ramp vehicles and guiding reasonable lane-changing activity are urgent problems for traffic researchers and engineers. This paper is concerned with lane-changing spacing intervals and reasonable lane-changing locations in off-ramp areas of urban expressways. This paper searches for the optimizing mechanism of lane-changing spacing intervals to promote the road capacity of existing off-ramps by guiding and restraining driver lane-changing behaviors. Based on the research in this paper, two ways can be realized to solve the off-ramp congestion in engineering by determining reasonable lane-changing spacing intervals for certain off-ramp areas and traffic volume demands.
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