The Atlanta City council approved a nearly $4 million art project for Hartsfield-Jackson International Airport with a 10-2 vote Monday.

Council members Yolanda Adrean and Alex Wan voted against the measure. Adrean has raised questions about the cost of the piece, among other issues.

The long-delayed project, called Flight Paths, will be the most expensive piece of art for the airport to date. It will turn the 450-foot corridor between Concourses A and B into a virtual forest with simulated sunbeams, birds, fireflies and a rainstorm. The estimated cost of the art installation increased from about $1.3 million early on to nearly $4 million today, including about $2 million for electrical work.

The project is expected to be completed by January 2014.