Those numbers/percentages are usually the "civil works", i.e. the concrete/steel viaducts, piers, station frame; there's a ton of other stuff (track, signalling, electrics, rolling stock, etc.) to catch up on that, once that's done. And the new intercity long-distance rail station (replacing Hua Lumphong) probably needs to be finished a bit too as this is a terminus for the dark red line, during the first "phase (Bang Sue to Rangsit).

If you drive north from the city to say, Don Meuang Airport, you'll see this line, and the stations on the left. Or check out Google Maps, satellite view and you can see the tracks and stations.