He said the government has several plans to expand both the North and South Expressway and expand the Buendia skyway to Balintawak.
Diaz explained that instead of just having two separate economic zones in the North (basically the Subic Freeport and Clark Special Economic Zone) and in the Calabarzon (Calamba-Laguna-Batangas-Rizal-Quezon), it may be better to integrate both areas and have one big economic zone which may be called a megazone with Manila as the hub.
To connect both zones, Diaz said, government is studying a plan to expand the skyway from Buendia to Balintawak, thus finally connecting the North and Luzon Expressway.
"The government is eyeing official development assistance funds from Japan, specifically from the Japan Bank for International Cooperation (JBIC), to finance the expansion of the skyway as well as the expansion of the North and South Expressway," Diaz said.
The 17.5-kilometer extension of the skyway from Buendia to Balintawak, Diaz said, is estimated to cost P20 billion to P25 billion if steel girders are used instead of concrete.
"The use of steel girders would make the construction much faster and would cause less of a traffic problem," he said.