Abstract
Many intersections around the world are irregular crossings where the approach and exit lanes are offset or the two roads cross at oblique angles. These irregular intersections often confuse drivers and greatly affect operational efficiency. Although guideline markings are recommended in many design manuals and codes on traffic signs and markings to address these problems, the effectiveness and application conditions are ambiguous. The research goal was to analyze the impact of guideline markings on the saturation flow rate at signalized intersections. An adjustment estimation model was established based on field data collected at 33 intersections in Shanghai, China. The proposed model was validated using a before–after case study. The underlying reasons for the impact of intersection guideline markings on the saturation flow rate are discussed. The results reveal that the improvement in the saturation flow rate obtained from painting guide line markings is positively correlated with the number of traffic lanes, offset of through movement, and turning angle of left-turns. On average, improvements of 7.0% and 10.3% can be obtained for through and left-turn movements, respectively.
Highlights
An intersection is a key point in addressing traffic problems in an urban road network [1]
Owing to several factors, such as limitations on land use, many intersections are irregular crossings where the approach and exit lanes are offset or the two roads cross at oblique angles, as shown in Figures 1(a) and 1(b), respectively
In China, the application conditions and methods for intersection guideline markings are set in the Chinese road traffic signs and marking codes [13, 14]
Summary
An intersection is a key point in addressing traffic problems in an urban road network [1]. To calculate the saturation flow rate more accurately, factors such as intersection geometry, traffic conditions, and signal control are taken into account to modify the basic saturation flow rate Many countries formulate their Highway Capacity Manuals according to their particular circumstances, which result in different saturation flow rate. With respect to signal control factors, Radhakrishnan et al highlighted the effect of vehicle type, lateral position on the roadway, and green time on the discharge headway They proposed a discharge headway model which could be used to acquire saturation flow rates and capacity at signalized intersections [30]. Sharma et al analyzed queue discharge characteristics at signalized intersections under heterogeneous traffic conditions and on the effect of a countdown timer on the headway distribution based on the data collected from two intersections in Chennai, India [31]. The reasons for the impact of intersection guideline markings on the saturation flow rate are discussed
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