A decision by Mexico's President Andres Manuel Lopez Obrador to scrap a partly built $13 billion Mexico City airport has raised questions about the feasibility of his alternative plan and the consequences of the change.

Lopez Obrador aims to add two runways to the military air base at Santa Lucia, some 29 miles by road north of the current facility, Benito Juarez International Airport, then connect the two. He said it can be done for 70 billion pesos ($3.5 billion). Companies already contracted by the airport group may be able to transfer their contracts to Santa Lucia or reach new agreements.

The government also is studying plans to upgrade the Benito Juarez hub and Toluca International Airport, which is 41 miles away, for about 5 billion pesos ($265 million).

The airport's cancellation may require the government to put up extra funds to prepay bonds issued to finance it, outgoing President Enrique Pena Nieto said. The group building the Texcoco hub issued $6 billion in bonds and $1.5 billion in an investment trust, backed by the current airport passenger tax.

Industrial Info is tracking $3.83 billion in projects at Mexico's airports. Click here to see projects.