Work zones exist widely in cities of many countries and have a significant negative impact on city traffic. The majority of the existing studies only focused on freeway work zones, while the work zones on urban arterials have not been investigated carefully. For the first time, this paper focuses on a specific type of work zone that is located within the area of the intersection, namely, the island work zone, and proposes a novel model for the traffic flow of the island work zone based on the social force theory. Compared to the existing traffic flow models, such as the car-following and lane-changing models, the proposed model can capture the special characteristics of the traffic flow in the island work zone, such as heterogeneity, no lane division, and irregular boundary. The field data collected in Chengdu, China, are used to calibrate and validate the proposed model. Simulations are also conducted to investigate the variations of traffic flow characteristics for different work zone features. The results display that the model can replicate the heterogeneous traffic flow of the intersection with island work zone with high performance. When an island work zone is located close to the intersection approach, it will significantly block the entrance of vehicles. When the work zone occupies over 1 m of the median divider, its impact on the traffic flow will become very significant.