MANILA, Philippines — Metro Rail Transit Line 7 (MRT-7) has undergone so many changes from its original design that the government is hiring an engineering consultant to look at all of them.

The three rail systems in Metro Manila by average ferry more than 800,000 commuters daily—MRT 3, the busiest at 357,000, LRT 1 at 323,000 and LRT 2 at 155,000. Ridership across all train lines ...