| 2. | For the remaining eight at - gradeoverhead stations ( tseun wan , kwai hing , kwai fong , ngau tau kok , kowloon bay , kwun tong , heng fa chuen and chai wan ) , retrofitting of platform screen doors involves major alterations to the stations and tunnel ventilation , air - conditioning and smoke extract systems . since such at - gradeoverhead stations are not designed with air - conditioning and ventilation systems , retrofitting works are subject to technical constraints
至于其馀8个现时没有月台幕门的地面及高架车站（即荃湾、葵兴、葵芳、牛头角、九龙湾、观塘、杏花?及柴湾） ，加装月台幕门系统须涉及重大工程，包括车站及隧道通风系统、冷气系统及抽风系统等的大型修改工程。 |
