By Howard Monroe

PHILADELPHIA (CBS) — SEPTA is preparing to increase its service as more people return to offices, but by doing that they’re going to make millions of dollars of improvements. CBS3’s Howard Monroe got an exclusive look at the critical infrastructure repairs.

“The congestion will come back and we have to be there to be the economic driver for the city,” SEPTA’s deputy general manager Bob Lund said.

READ MORE: 21-Year-Old Aaron Scott Charged After Shooting Near Lincoln High School Killed Man, Injured 16-Year-Old

But first, the hard work has to be done. SEPTA is currently in the middle of a multi-million dollar project to repair its trolley tunnel.

The tunnel runs from 40th Street in West Philadelphia to 13th Street in Center City.

“Our trolley system is key to getting passengers from West Philly into Center City,” chief engineer Dave Montvydas said.

SEPTA’s Deputy General Manager Bob Lund and Chief Engineer Dave Montvydas gave CBS3 exclusive access to the work being done.

Some 300 SEPTA workers are working around the clock to replace or repair station platforms and parts of the tunnel to fix signal systems and the tracks, paint and improving lighting.

Sometimes there is no replacement for manpower. Crews are replacing six miles of wire and they’re doing it by hand.

READ MORE: Plan Unveiled To Resolve Battle Over Control For Upper Darby's 'Summer Stage'

The tunnel had to be shut down to complete the work. SEPTA says workers can work more efficiently and safely with it closed.

The blitz cost? $10 million.

It’s part of SEPTA’s $1 billion trolley modernization plan.

“Without our trolley tunnel we don’t have enough buses or roads to get all of those people into the city in a timely fashion,” Montvydas said.

SEPTA says ridership at its lowest point during the pandemic was just 10% of what it was in 2019. But, it has since recovered to about 40% and according to a new report by the Center City District, business leaders are expecting more workers, business travelers, tourists and students to return to the city over the summer.

SEPTA says by doing this work now, the system will be ready.

“The city is going to return,” Lund said. “We’re all confident in that. It may be a little longer than we want, but we’ll get the city back to where it should be and to do that, public transit is the key.”

MORE NEWS: NFL Kicks Off $6.2M Responsible Betting Campaign As Interest In Gambling Increases

The trolley tunnel is set to reopen on July 26 and overnight trolley service in Center City will resume in September.