## 1 Introduction  
It is well known that the implementation and adoption of new energy vehicles are crucial to the success of the global low-carbon environmental protection strategy. Accordingly, almost all countries are vigorously encouraging and embracing the development of new energy vehicles, such as electric vehicles (EVs). According to a statistical report of the International Energy Agency, there were more than 6.85 million pure EVs in the world in 2020, with more than half of them in China. By 2021, the number of EVs in China reached 7.84 million as reported by the Ministry of Public Security of China. Compared to traditional internal combustion engine vehicles (ICEVs), EVs usually have more integrated circuit systems, which could cause electrical fires. As reported in the EV Safety Global Technical Regulation in 2020, 38% of all EV fires are caused by thermal runaways and occur while they are in the parked state. Compared to the effects of electrical fires on the passengers while EVs are moving, electrical fires that occur while they are in the parked state usually affect the pedestrians. However, investigation into the factors that result in harmful impacts on pedestrians has received insufficient attention. According to a general survey report on Beijing parking resources released by the Beijing Municipal Transportation Commission in 2017, roadside parking resources in urban residential areas are scarce. Many people are forced to park their vehicles on secondary trunk roads and low-grade roads, where there is always a dense and complex pedestrian flow. Compared to blocked outdoor parking or underground parking, roadside parking has a complicated pedestrian flow, insufficient safety distance and a lack of fire extinguishing facilities. Roadside parking also increases road congestion, reduces traffic capacity and increases the potential hazards and difficulties in rescue operations. Therefore, when an EV fire occurs under such circumstances, they could result in disastrous consequences for the pedestrians. To date, many scholars have dedicated a lot of effort towards studying EV fires, which mainly comprise three stages: (i) the mechanism of the EV fires, (ii) the fire onset stage and (iii) the fire investigation stage. In particular, in the first stage, efforts were taken to conduct thermal runaway tests on batteries to investigate the internal mechanism of the EV fires and develop the corresponding protection strategies [1]. In the second stage, studies on the impacts of the EV fires were analyzed to support pedestrian evacuation and fire safety system design [2; 3; 4]. In the last stage, some studies summarized the practical features of the EV fires and tested the effects of different fire extinguishing agents on them [5; 6]. Given the high possibility of EV fires compared to fuel vehicle fires, more attention should be paid to the consequences of EV fires. However, few studies have analyzed the effects of the EV fires on pedestrians while they are parked on the roadside. Accordingly, this study aims to develop a numerical model to simulate the effects of fires in EVs on pedestrians caused by the sudden thermal runaway while these vehicles are parked on the roadside. To investigate this problem, this study set up a rectangular solid flame model (SFM) and a point source model (PSM) as the scenarios for the EV fires and then the thermal radiation field was constructed. In addition, by calculating the thermal radiation received by the pedestrians fleeing from the fire, the damage and summation of the thermal radiation received by the pedestrians fleeing in different directions and at different speeds can be estimated. Subsequently, the optimal fleeing direction can be determined to minimize the total received thermal radiation. Furthermore, insights from the simulations can also provide a scientific basis for the design of safe and reliable roadside parking management systems. To investigate the aforementioned research gaps, the structure of this paper is organized as follows.