In the late 1970s many arterial roads were redesigned as ejes viales; high-volume one-way roads that cross, in theory, Mexico City proper from side to side. The eje vial network is based on a quasi-Cartesian grid, with the ejes themselves being called Eje 1 Poniente, Eje Central, and Eje 1 Oriente, for example, for the north-south roads, and Eje 2 Sur and Eje 3 Norte, for example, for east-west roads. Ring roads are the Circuito Interior (inner ring), Anillo Periférico; the Circuito Exterior Mexiquense ("State of Mexico outer loop") toll road skirting the northeastern and eastern edges of the metropolitan area, the Chamapa-La Venta toll road skirting the northwestern edge, and the Arco Norte completely bypassing the metropolitan area in an arc from northwest (Atlacomulco) to north (Tula, Hidalgo) to east (Puebla). A second level (where tolls are charged) of the Periférico, colloquially called the segundo piso ("second floor"), was officially opened in 2012, with sections still being completed. <answer>The Viaducto Miguel Alemán</answer> crosses the city east-west from Observatorio to the airport. In 2013 the Supervía Poniente opened, a toll road linking the new Santa Fe business district with southwestern Mexico City.
What main road leads to the airport?
The Viaducto Miguel Alemán