The increment of the population in Kuala Lumpur had caused the LRT stations become crowded with excessive demand during the peak hours. This also includes the underground LRT stations especially near the KLCC area. Unfortunately, limited study was done regarding the pedestrian and train passengers at underground spaces in Malaysia. Due to this problem, the facilities provided will not be enough and suitable for the increment of the pedestrian volume in the future. Thus, more studies focusing pedestrian evacuation in underground spaces is required. This project aims to establish the fundamental diagram of pedestrian speed-flow-density relationship at vertical spaces in underground train station for understanding the appropriate emergency response plan (ERP) that suitable for the case of KLCC train station.