ISLAMABAD   -   Pakistan Tourism Development Corporation (PTDC) on Thursday urged tourists to adopt precautionary measures to avoid any untoward incidents during travelling at vulnerable sites in Northern Areas. The PTDC warned the tourists owing to their safety as large number of people thronging from various parts of the country to enjoy their trip.  An official in PTDC told APP that the snow and clad-mountain were attracting and catching eyes of massive number of tourists to these scenic sites at hilly areas which resulted in extra traffic load on the roads.  He urged the citizens to use their own line and avoid using the dual line to refrain from miseries and hardships.  The visitors are advised to carry warm clothes, keep fuel tanks full and avoid unnecessary travel after 8:00 pm. He further said that the families with infants and asthma patients were also advised to avoid travelling to the Northern Areas.