Few things have changed in appearance at the Hennepin County Government Center since it was built in the mid-1970s. But starting next month, a critical feature of the 24-story downtown Minneapolis tower will undergo a major renovation: the building’s 20 busy elevators and six escalators.

“It’s getting to the point where we aren’t able to get replacement parts, and the useful life of the mechanical system has come to an end,” said Margo Geffen, the county’s facilities manager. “We are hoping for as little disruption as possible.”

Work on the $19 million project is expected to begin Oct. 7 and take about four years to complete. The plan is to take down one elevator at a time, she said, in hopes that the newly renovated elevators will work more efficiently and help take up the slack.

The Government Center has a bank of eight elevators in each of the courts and administration towers, providing service to 10,000 people daily.

Hundreds more use the three-story escalators in the building’s atrium, along with elevators to the parking ramp and an elevator for people with disabilities.

In 2014, the building’s elevators and escalators were identified as a preservation project. At the time, the plan was to replace obsolete components, add mechanical backups and perform partial electrical upgrades.

Two years later, a county-commissioned study by elevator consultant Lerch Bates resulted in a dramatic change in the project’s scope, Geffen said.

The study recommended a more comprehensive approach to updates and modernization by replacing the direct-current motor drive with an alternating current system. That will make the elevators more efficient, safer and more environmentally friendly, said project manager Dan Missaghi. The replacement cost was estimated at $13.6 million.

In 2017, the board approved an on-site study that included physical testing and observations of elevator shafts. The inspection found that shaft walls needed restoration and that the enclosed spaces needed better heating and cooling, Missaghi said.

Statewide building code changes enacted after the 2016 estimate mandated additional changes including stairwell remodeling, wider elevator cars and new safety features for escalators. The code updates added another $4.5 million to the projected cost.

Shaw-Lundquist Associates, which bills itself as one of the largest Asian-American-owned construction firms in the United States, was chosen earlier this year for the job.

The project is expected to improve elevator performance and wait time, increase safety by adding a secondary emergency brake, and improve energy efficiency by 30%. The new motor system will eliminate carbon dust released by the direct-current motor drive.

Although the elevator cars are nearly 50 years old, they haven’t needed much repair and meet current safety standards, Geffen said.

The Government Center soon will start another major project to replace all the piping in the court tower, “but the elevator project is pretty big,” she said.

“It’s something that will be seen by everybody who comes into the center,” she said.