TO expand Metro Line 11's passenger capacity, four to six trains will be added to its fleet, the city's Metro operator said yesterday.

Another nine Metro lines — 1, 2, 6, 7, 8, 9, 12, 13 and 16 — are also slated for expansion to cope with increasingly heavy passenger traffic.

More than 1.64 billion trips were recorded by the city's Metro network in the first six months of this year, up 12 percent over the same period last year.