Evaluation of whole body vibration and back pain problem among Light Rapid Transit (LRT) drivers by Jalil, Azlis-Sani, Zaid, Muhammad Firdaus, Yahya, Musli Nizam, S. M. Ismail, S. M. Sabri, Ahmad Tajedi, Noor Aqilah, Abdul Aziz, Roseni, Md Zein, Raemy