Mexico's transport and communications ministry (SCT) said that construction of the Mexico City-Toluca railway line is 35% complete.
Engineers will carry out operational tests along the Zinacantepec-Lerma stretch around the end of the year, minister Gerardo Ruiz Esparza said in a statement.
The interurban railway will have six stations and the capacity to transport 230,000 people a day. Travel time is expected to be 39 minutes and trains will reach speeds of up to 160km/h.
The line is due to become operational in April 2018, a year later than originally scheduled.
The cost of the project has risen to 44bn pesos (US$2.37bn ) from 42.7bn pesos last November because of cost adjustments, inflation and a weakening peso, SCT has said.
In the past few months, construction of the Mexico City-Toluca passenger train line has been impacted by accidents.
The 58km line from Toluca, capital of Mexico state, to Observatorio station in Mexico City, should be 75-80% complete by the end of the year, SCT has said.