Construction meant to fix a notorious railroad bottleneck on the South Side is expected to begin in Spring 2019 now that the funding for the construction phase of the project is mostly secured, transportation officials said on Wednesday.

Repairs on the 75th Street Corridor have been in the works for more than a decade. Last month, a federal grant worth $132 million essential to kick-start the first construction phase of the project came through, prompting both private and public stakeholders to pony up the rest of the funds needed.

In all, transportation officials with the Chicago Regional Environmental and Transportation Efficiency (CREATE) Program said they have $474 million slated for the 75th Street Corridor project — about half of the total needed to complete all of the proposed repairs.

“This is but one step in a long and ongoing battle to untangle Chicago’s railroads, but it’s a big one,” the Midwest High Speed Rail Association said in a statement. “Not only will it mean better reliability and improved frequency for existing Amtrak service, it will make it easier to add new service to destinations around the Midwest.”

Every day, 30 Metra trains and 90 freight trains make their way through the 75th Street corridor. To pass through the corridor, trains must cross the Belt Junction — where five rail lines merge into two — and the Forest Hill Junction, described by officials as an “intersection but for trains” where trains traveling on east-west lines cross with those heading north and south.

It’s a headache for everyone involved: Trains routinely struggle with delays coming in and out of the city through Belt Junction, triggering road traffic delays at rail crossings. Air quality suffers as a result, as does the economy.

It takes an average of 30 hours for a freight train to make it through the Chicago region, and Belt Junction and Forest Hill Junction take a big chunk of the blame.

“It’s the most congested rail chokepoint in the Chicago Terminal,” said Bill Thompson, chief engineer at the Association of American Railroads. “It’s a nightmare.”

Starting in March 2019, officials expect construction to begin on a new flyover that takes the north-south CSX line over the east-west lines at Forest Hill junction and 71st Street. This will allow north-south trains to pass without interfering with east-west trains, such as Metra’s Southwest Service. It will also keep 71st Street from being blocked by slow-moving freight trains.

At a tour of the site where the flyover will be built, officials told reporters on Wednesday that the repairs will save Metra users an average of four minutes per ride.

A chunk of the $474 million will also be used to improve access to a nearby yard and increases its capacity so that freight trains don’t block the main line.

The secured financing of the first construction phase of the 75th Street corridor project also greenlights design to begin on fixes to the Belt Junction bottleneck and another flyover that will allow Metra Southwest Service trains to move through the area without conflict and then proceed to LaSalle Street Station, instead of Union Station.

Construction on that particular project is dependent upon further federal funding, which is granted on a year-to-year basis.

Transportation officials hope that this year’s grant is a sign that the federal government understands the need for the fixes and will continue to financially support them in coming years.

“We don’t expect the federal government to help start the job and not finish it,” Thompson said.

So far, CREATE has completed or begun 29 of its planned 70 projects with nearly $1 billion spent. The total cost of all of its projects is projected to be $4.4 billion.

All in all, the backers of CREATE promise taxpayers a big return on their investment. The group claims it will add an estimated 44,000 jobs and generate $31.5 billion in economic benefits over the next three decades. Additionally, CREATE will allow the region to handle up to 50,000 more freight trains by 2051.

“Chicago’s already the rail hub of the country — if not the world. 22,000 shipping containers pass through Chicago every day, about 8 million every year. That’s comparable to what goes through the Port of Los Angeles, the largest port in North America,” Jeffrey Sriver, director of transportation planning and programming at the Department of Transportation for the City of Chicago. “The 75th Street Corridor projects will help us cement that legacy.”