Lime is the city where it never rains. On the Pacific seacoast, the back to the Andes, clouds go over but only unload in the mountain ridge. The strategic location of Lima is due to the outstanding port of Callao from where Peru was linked to the Spanish Empire.
Lima has thus a linear structure along the coast. Very simple to serve by a commuter train. No one has yet seriously proposed to build it. It might be about time.
On the other hand, Lima has taken an incredible amount of time to build a metro line that does not even understand the structure of the metropolis. With a social equity concern serves rightly informal areas, but does not help to position Lima in an international metropolitan context.
Lima needs a metropolitan vision still lacking.