This station has an elevated platform.
There is a parking lot under the elevated road.
There are plans to elevate this road.
I drove along the elevated road.
高価 (expensive) and 高架 (elevated) are pronounced identically but have completely unrelated meanings.
効果 (effect, result) shares the same reading こうか with 高架 (elevated) but refers to a completely different concept.
Compound of 高 (high) and 架 (erect, build), literally meaning 'built high'. The kanji 架 is used in words for spanning or constructing frameworks.