Fog has a negative impact on freeway traffic safety and efficiency due to the reduced visibility. Variable speed limits (VSL) can improve traffic states under foggy weather conditions. However, most of the previous researches calculated the speed limits by stopping sight distance model, which is likely to cause sharp fluctuations. This paper presents a VSL control method based on the real-time road visibility and traffic states. The speed limits of road sections are determined by maximum safe speed, speed difference between adjacent sections, etc. A part of G4 freeway is selected to evaluate the proposed VSL control method, and simulation experiments are conducted by using VISSIM simulator. The simulation results show that the lowest speed has increased by 34.9%, and the maximum speed difference of adjacent links has decreased by 67.77%, compared with no VSL control. The simulation indicated that VSL control can ease the congestion caused by low visibility.
Control Method of Variable Speed Limits for Freeways under Foggy Weather Conditions
17th COTA International Conference of Transportation Professionals ; 2017 ; Shanghai, China
CICTP 2017 ; 382-392
2018-01-18
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
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