Chicago's 110-story Willis Tower. Otis Elevator will modernize the 83 elevators and 97 passenger cabs in Chicago's landmark Willis Tower. Scope of the contract includes the elevators' machine rooms, motors, cables and controls, and is part of a larger $500 million renovation project.

As part of the agreement, Otis will also provide maintenance service for the elevators for 10 years.

The Willis Tower elevator system makes more than 46,000 daily trips and serves an estimated 5.8 million people each year. The modernization project will provide more efficient elevator service for tenants and visitors, reducing travel time during peak hours by up to 30 percent and cutting energy costs by an estimated 35 percent.

Work on the 110-story-tall tower — earlier known as the Sears Tower — began in 1970. The building was renovated in 1985 when a new entrance atrium was added. In 2009, the building was renamed Willis Tower. Six years later, Blackstone Group bought the building for $1.3 billion.

The current renovation project will include more than 300,000 square feet of new commercial retail space.