The Federal Transit Administration in the US state of Arizona has approved Metro Rail's request to begin the project development for the Central Mesa light rail extension.
The approval marks the first step in receiving $75m in federal funding for the 3.1-mile extension, which runs from the current end-of-line at Sycamore to Mesa Drive.
Metro will start the $12.5m design and engineering work in Central Mesa, which has been awarded to California-based Jacobs Engineering.
The total project cost is about $200m and is funded by regional and federal grants.
The engineering work will take about two years and the extension is expected to open in 2016.