Construction on Apple Inc.'s Americas Operations Center could be completed by the end of 2014 or early 2015, according to city officials.

Apple's pedestrian-friendly campus is located on 38 acres of land at 5501 and 5505 Parmer Lane in the Riata Vista Office Complex. Construction for the operations center began in September 2012 after Apple purchased the land in June 2012.

"They've moved very fast on this project," said Dan McNabb, deputy building official and manager of building inspections for the city of Austin. "You're looking at anywhere from a year to a year and a half from the time of start to completion on these [types of] projects in general."

McNabb said two buildings and one parking structure have been completed since construction began. The two office buildings comprise about 290,000 square feet, and Apple has received temporary occupancy certificates for employees to work in the buildings until construction on the entire campus is finished.

The city is reviewing Apple's proposed plans to build four additional buildings that total 513,000 square feet, McNabb said. Two more parking garages are also included in these plans, but these projects have not received building permits from the city. The site plan for the complex indicates Apple could build about 1.13 million square feet of parking garage space.

The original site plan for the campus included two retail buildings with 34,794 total square feet and one 5,250-square-foot restaurant.

Apple could decide to include retail, restaurant or any other space for accessory use, as long as it is less than 10 percent of the total square footage. Accessory use space is dedicated for people working in or visiting the facility but not for public use.

Apple announced its plans in March 2012 to invest $304 million into the operations center and hire more than 3,600 employees. The city of Austin approved an $8.6 million economic incentive agreement for Apple's investment in Austin and hiring the new employees by Dec. 31, 2021. Apple will also receive $21 million from the state.