The 20-year-old computer-aided dispatch system that forms the guts of Chicago’s 911 center will be replaced by a $75 million upgrade that is expected to dramatically improve both the speed and quality of emergency response.

After years of planning, City Hall has chosen TriTech Software Systems to install the complex software and hardware systems that will allow Chicago to comply with a 2020 deadline to make the switch to, what’s known as “Next Generation 911.”

When the three-year transition is completed, people who live, work and play in Chicago will finally have the ability to send texts, photos and videos from emergency scenes, improving the quality of the city’s response.

The new system will automatically locate the cellphone caller’s location, precisely detect the location of the nearest first-responder and prioritize which incident is most urgent.

The new technology will also integrate into the city’s sophisticated technology systems —from ShotSpotter gun-shot detection technology to the vast network of surveillance cameras — providing first responders with a panoramic view of every incident.

That’s expected to dramatically improve both “situational awareness” and officer safety.

The new system will pave the way for the city to streamline its police and fire dispatch operations by providing a common platform that gives both groups access to the same critical information in real time.

That unified view will help the Chicago Police and Fire departments share critical information and enhance their coordinated response.

“Our CAD system is over 20 years old….It doesn’t allow us to take advantage of…enhanced location services, enhanced [geographic information system] capabilities. Texts to 911,” Zach Williams, director of information systems for the city’s Office of Emergency Management and Communications, said Wednesday.

“It’s a lot of knowing where people are at and…being able to utilize where people are at to get them the fastest response and get them the response the right way the first time.”

Installing the new system without a hiccup won’t be easy. Not while continuing to operate a 911 center that gets 4.5 million calls for emergency service every year.

That’s why the phase-in is expected to take three years.

“You’re not just talking about hundreds of… call takers and dispatchers. It’s in every CPD and CFD vehicle. Their administration has to be trained as well. It’s gonna be a huge undertaking,” Williams said.

“We have to train people as close to implementation as possible. So getting all of that training together and packing all of that in once the system is up and running and configured the way we like it — it’s a big challenge. That’s why it’s gonna take a little while.”

Williams can only hope the transition is smoother than it was the last time around.

The current computer-aided dispatch system tailor-made for Chicago made a problem-plagued debut that coincided with the 1995 opening of the $217 million 911 center.

For the first two years, the Chicago Fire Department continued to dispatch emergency vehicles manually because of a shortage of personnel and persistent problems with the computer software.

In 1997, an exasperated then-Mayor Richard M. Daley hired a retired U.S. Navy commander, to correct the system’s problems.

Dispatchers and call takers were hired. A room where alarms from 1,622 schools, hospitals and nursing homes are received was monitored round-the-clock, instead of being unstaffed overnight. Automatic vehicle locator devices were installed in 318 Fire Department vehicles.

And city contractors engineered a software fix to make fire call boxes compatible with the integrated mapping system that formed the guts of computer-aided dispatch.

A computer-generated voice that relays emergency dispatches to Chicago firehouses was replaced by a voice that sounds human, eliminating the last major kink.

Although the $75 million price tag for the new computer-aided-dispatch system is steep, Williams maintained that it will actually save the city money.

“Our current CAD system…was built for Chicago. And over the last 20-plus years, it has been constantly adapted to Chicago. We’re the only city in the world that is using this exact version of this exact CAD, which is very costly,” he said.

“When you buy a new software like we have, it’s utilized in other cities…It’s much cheaper to maintain and upgrade, as opposed to the one-off system we currently have.”