Somewhere behind these mountains lies the Mount Pinatubo volcano. Erupting in June 1991, the Maculcol tributary became a river of volcanic ash and in some areas, within centimetres clearing distance from the under-belly of the old Maculcol bridge.

A part of the National Highway leading north to Iba, Zambales and beyond, it was necessary to reconstruct the 430 metre long bridge, at a higher elevation with a distance 5.9 metres from the ground.