Security arrangements have been tightened ahead of the 69th Independence Day across Punjab, especially in border districts in the wake of Gurdaspur terror attack last month, besides Haryana and Chandigarh. Security forces are on high alert, officials said on Wednesday.Security has been strengthened at the venues where dignitaries will unfurl the Tricolour and important railway stations including Chandigarh, ludhiana, Jalandhar, Amritsar, Panipat, Ambala, besides key interstate bus terminals and other vital installations, the officials said.