Research on the Design of Central Median Opening During Expressway Reconstruction and Expansion
To achieve the objective of maintaining traffic flow while carrying out construction in highway reconstruction and expansion projects, traffic diversion is required through openings in the median for traffic maintenance. The design of these openings directly affects traffic safety and operational efficiency. Focusing on highway reconstruction and expansion projects with four lanes maintained during construction, this study considers two typical traffic transition scenarios: bidirectional traffic on both carriageways transitioning to bidirectional traffic on a single carriageway, and bidirectional traffic on the left carriageway transitioning to bidirectional traffic on the right carriageway. Median opening alignments were designed for different operating speeds. A VISSIM-based microscopic traffic simulation was then conducted to evaluate the effects of different opening lengths and alignment configurations on traffic flow from three perspectives: delay, traffic conflict rate, and speed stability. Based on the simulation results, an optimal range of median opening lengths and recommended alignment designs were proposed for four-lane traffic maintenance sections within highway construction zones.
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