The extension was built by Foothill Transit Constructors, a joint venture of Kiewit and Parsons, and the project was managed by Foothill Gold Line Construction Authority (FGLCA).

Construction started in 2011 and included 24 bridges, 14 level crossings, six new stations, relocation of a 6.4km rail corridor with two bridges that had to be relocated within a 72 hours, and a maintenance and training centre in Monrovia with space for 84 LRVs. The latter is designed to use 35% less water and energy than similar facilities and is equipped with a 178.5kW solar panel array, LED lighting, a storm water collection system, and drought-tolerant landscaping.

"The Foothill Gold Line was built on time and on budget with an exceptional safety record thanks to a strong collaboration with Kiewit, Parsons and the corridor cities," says FGLCA's CEO Mr Habib Balian.

Advanced conceptual engineering is underway for a $US 1bn 19.8km extension from Azusa to Montclair, although funding has not yet been arranged for the project.