The % relates to civil works progress ie. the actual construction of viaducts, tunnels, stations etc. S&E means signaling and electrical. The SRT Dark Red line civil works were completed some 18 months ago. The period since then has been fitting out the station, laying of tracks and installation of the catenary system (overhead electrical)..

For some lines such as the MRT Orange line - which has 4 separate civil work contracts for different sections of the line - there are progress update %s for each contract. Indeed, there are even specific progress updates for each station. However, this level of detail is not generally of interest to most.