# Evaluation of Different Work Zone Road-Occupation Schemes for Monorail Construction
## 1 Introduction  
The rapid development of China's transportation industry has led to a swift increase in the number of vehicles in urban areas, and the traffic pressure in cities is increasing gradually. In order to alleviate the congestion and air pollution caused by the imbalance between urban transportation supply and demand [1], in addition to accelerating the construction of subways and urban expressways, China has been vigorously developing monorail transportation in the past two years, constructing tracks on the central dividing strip or narrow streets of the road. This type of rail transit does not occupy the road surface separately and belongs to a medium-capacity urban rail transit system with a capacity similar to that of a subway system [2]. Although the monorail does not occupy the road surface, it needs to occupy the urban ground to build the foundation or place construction tools during the construction process. During the construction process of a monorail, 2-3 lanes are generally required, with only the median strip of the road being used to build the foundation and other places being used to place construction equipment. Whether the work zone is situated on the road or near the intersection, its existence will inevitably have an impact on the traffic flow passing by [3, 4]. Due to the long construction length, the monorail work zone often occupies the entire lane of two adjacent intersections and seriously distorts the traffic flow of vehicles at the entire intersection [5], leading toa decrease in the traffic capacity of the intersection [6; 7]. And intersections are already the bottleneck of urban road traffic. Setting up work near the bottleneck of urban roads will inevitably further exacerbate traffic congestion [8], even if it would endanger traffic safety [9]. Over the years, in an effort to alleviate the effects of construction work zones on traffic efficiency, researchers and policymers in the field of transportation have been exploring various strategies. Some scholars have evaluated the impact of road construction through dynamic traffic allocation and compared alternative construction schedule plans in order to choose the optimal plan to reduce travel delays and improve road capacity [10; 11]. Several studies have analyzed the impact of construction work zone length on road capacity [12; 13; 14]. In addition, scholars have found that a work zone located at the intersection causes deviation of the road, which in turn leads to deviation of the main traffic flow, and have proposed two road improvement plans for this purpose [15]. Due to the limited location selection of the construction work zone studied above, the main idea is to improve the form of the construction work zone to ensure smooth traffic flow and increase road traffic capacity. When constructing a monorail, the location of the ground construction work zone is relatively flexible, and different middle lanes can be chosen as the work zone (including the median strip) according to the actual situation. In most practical situations, the setting of work zones is often selected based on the actual form of land required for maintenance or construction. This type of work zone is objective, cannot be selected, and has a relatively short existence time with little impact on traffic. However, the construction of monorail transportation takes longer than ordinary construction operations, usually taking several months or even years. Reducing the impact of monorail work zones on intersections has become an urgent issue to be addressed. Therefore, this paper primarily investigates the influence of work zone layout on intersections during the construction of monorail systems. Research on the effects of work zones predominantly falls into two major categories. The first category pertains to the work zones on highways, encompassing aspects such as traffic capacity [16], work area impact area [17], and traffic flow prediction models [18].