Caterpillar Inc. has unveiled a new headquarters campus in Peoria, Ill., that will include three office towers containing 1.9 million sq ft, sited on 31 acres along the city's riverfront.

The heavy-equipment manufacturer is working with a design-build team of construction manager Turner Construction, architect Gensler and engineer Farnsworth Group to plan and execute the project, which covers six city blocks.

Caterpillar's existing 500,000-sq-ft Peoria headquarters is nearly 50 years old and busting at the seams, with 2,200 office workers occupying the building today. Construction of the new campus, sized for 3,200 workers, will take several years to complete and will not break ground until "at least 2016," according to information ENR obtained from its parent company, Dodge Data & Analytics.

"While we are doing minor site preparation, there will not be construction this year," says a statement Caterpillar emailed to ENR. "Once construction begins, it is expected to take the better part of a decade to build the entire campus." Meanwhile, Turner says it is actively seeking subcontractors interested in bidding on the proposed work.

Cat has not yet disclosed costs for the project, which is to be built in phases. However, sources close to the project say it will cost more than $250 million to complete.

"Our plan is to reveal specific details when we are closer to formally breaking ground on the campus," says the company's emailed statement. "We certainly have estimates at this stage, and as you can imagine, a project this size and scope, located on a 31-acre campus, with a decade-long construction window will be a benefit for the region."

The announcement helps puts to rest any lingering rumors suggesting that Cat might move its headquarters outside Illinois. Peoria became the official home of Caterpillar in 1925, when two California-based machinery businesses, Holt Tractor Co. and C.L. Best Tractor Co., merged to form the Caterpillar Tractor Co.

Cat's transition to the Midwest took decades. By 1950, the company had still not finished moving its corporate offices to Peoria, where it had multiple manufacturing facilities, from San Leandro, Calif. When the current headquarters opened, Cat took in sales and revenues of $1.5 billion, had a corprate staff of 1,500 people and employed 56,000 total workers. It now sells $55.2 billion in goods with 114,000 employees worldwide.

Cat says it is negotiating with city officials in Peoria to resolve questions about green space, streetscaping and other civic improvements associated with the replacement headquarters.

"This campus represents an investment in both our people and community," says Cat Chairman and CEO Doug Oberhelman in a statement. "While we are moving forward, we will manage our costs very carefully in a tough global environment."

Renderings of the campus show the three towers rising 200 ft above street level on two podiums containing parking, fitness, child-care, restaurant and retail spaces. Sized to hold 3,200 people on eight occupied floors, the office towers would receive utilities from a central plant and connect through an enclosed pedestrian bridge to the Caterpillar Visitors Center, built in 2012.

At about 60 ft off the ground, a cantilevered, three-story horizontal office structure spanning the length of two city blocks would connect the towers. The long structure is shown detailed with a green roof and thick-yellow exposed perimeter truss whose diagonal members resemble the rear-leaning triangle shape of Caterpillar's signature "high-drive" tractor undercarriage.

Cat's current headquarters is a cross-shape-in-plan, nine-story building designed by Smith, Smith, Haines, Lundberg & Waehler, now HLW International, and built in 1967 by Huber, Hunt & Nichols, now Hunt Construction Group. Aerial renderings of the new campus show green space where that building now stands.