I had a chance to spend a day on the various KCSM lines around the Bajío in central Guanajuato state. At Escobedo, the busy yard classifies manifest and intermodal traffic between Mexico City, Lazaro Cardenas, Toluca and the mainline to the north. Much of the trackage through the Bajío (including Ferromex's lines) is of new construction dating to the 1970's and 1980's. The Mexican government realigned much of Linea B between San Luis Potosi and Mexico City. A new mainline (Linea BC) was built to the east of Escobedo, essentially bypassing the terminal. However, the yard is still busy today, and the historic station building is still in use by KCSM crews.
A yard job with tho KCS geeps switches the south end of Escobedo Yard while a road crew prepares to depart southward to pick up an empty grain train (based on their conversation with the dispatcher).
Just south of San Miguel de Allende, a southbound manifest meets a northbound intermodal train. This section of Linea BD was built in the late 1970's in order to accommodate the construction of Presa Allende, a large reservoir that flooded the valley floor to the left of the train. Notice that KCSM has installed signals to protect the automatic switches at each end of the siding. Although this is dark territory controlled by track warrant, the crews can operate the switches by radio, and the signals indicate how the switch is lined.
Below the dam that created Presa Allende, the original alignment of Linea B can still be driven. This winding canyon featured a long tunnel.