Writing about cities is an exercise in patience. The day a building opens or a ballot measure passes might feel exciting, but transformation is actually delivered in crumb-like increments over weeks, or months, or years.

Transportation, especially in a place like Los Angeles, is maybe the most frustratingly slow part of cities to chronicle. Alignments are difficult to plot and tunnels are expensive to dig.

But real change is not really about the infrastructure—it’s about how people will use it. On Friday, I visited a place that made me feel newly inspired about how LA is changing: the Regional Connector.

It’s the most important construction project in LA right now, and it is not a building. It’s a gargantuan subterranean structure that stretches 1.9 miles from Little Tokyo to the Financial District. When complete, it will provide a one-seat ride from Santa Monica to East LA, another from Long Beach to Azuza. That’s a distance of almost 40 miles, north to south, east to west, on one fare.

If you’re traveling through Downtown’s Bunker Hill, Civic Center, or the Arts District you might encounter a few bright yellow cranes on the skyline and hear some interesting sounds under your tires—that’s the temporary decking over the streets, which engineers have managed to make look convincingly like asphalt. On the surface, it might look like a mess. But the closed streets and construction fences denote that the right decisions are happening underfoot.

I got to tour two construction sites: where the project starts to burrow underground around Temple and Alameda, and in the station being excavated at Broadway and Second Street.

Getting down into the pit was an adventure. I rode a tiny elevator snapped together like an Erector set about 40 feet down, then descended the final 10 feet on a ladder. As I dropped into the cavern, the hum of the city was slowly replaced by the buzz of bright orange robot arms clawing into the room’s perimeter, a soft siltstone called the Fernando formation, which is more like a really hard clay. A stream of water dripped three stories from above, like a waterfall coursing over the rim of a canyon.

The space was as big, complex, and jaw-dropping as an underground cathedral. The tunnels are already finished; Angeli, the tunnel boring machine, chewed through the job at a speedy 190 feet per day. Now, the excavation of the room where I stood is burrowing down to meet them.

Along the northern wall, the construction team was assembling a monolithic structure that will shore up the Los Angeles Times Building’s foundation as the workers inch downward. When they are finished digging, the floor of the station will be nine stories underground, nearly as deep as the Los Angeles Times Building is tall.

As I picked my way over the rocks, which were the color of wet concrete and pleasingly damp to the touch, I was struck by a series of fluorescent numbers that are scrawled like graffiti on an ancient Brutalist structure.

The spray-painted numbers are dates, a way of marking the passage of time as the floor of the station box is excavated by the workers and their machines. Over time, the floor will sink lower and lower until it’s united with the tunnels.

In many other major cities, public transit infrastructure costs are ballooning as service is disintegrating. The Regional Connector project has been hit by its own delays and cost overruns. Replacing deteriorated utility lines added to the budget and timeline, and now the stations will open a full year later than planned, in December of 2021.

Still, after standing there, watching the tunnel emerge from the clay as if was being shaped by some unseen sculptor, it feels accurate to say that Los Angeles is moving towards a new future for its residents.

This is not to say that getting us to that future will be easy. The city is beset with problems that seem insurmountable at the moment. We have failed to provide enough places for our neighbors to live, we have surrendered far too much of our city to dangerous and deadly vehicles, and our daily habits are making our way of life untenable for the next generation. But I’d argue all these problems can be alleviated, if not solved, by giving every Angeleno better access to transportation options.

Ridership across Metro, namely on buses, has hit a 10-year low, mostly because people keep buying cars. Yet the Regional Connector project alone is estimated to boost ridership across the system by up to 17,000 trips a day. It will do that by fixing a simple problem—allowing people to more efficiently move from one train to another.

Under the streets, where the passage of time is etched in day-glo spray paint along a wall, the city is working the right way. The Regional Connector is a solution that will make LA better, amplified by an overwhelming show of confidence by a majority of voting Angelenos who agreed to tax themselves to finance the project. Below ground, things are falling into place.

The Regional Connector isn’t an attraction. Visitors will not come to see it. When it’s finished, Angelenos won’t even call it the Regional Connector. There will be only the slightest traces of it on the surface. We will know it works if we don’t notice it.

Metro says when the Regional Connector opens in 2021, riders can expect to shave as much as 20 minutes off their commutes. With every few feet of earth moved, I saw another 20 minutes that could make a difference in someone’s life.

Underground, I pictured how the future rail line might allow a recent graduate to afford to live closer to her new job. I envisioned a parent being able to get home to his kid before bedtime. I imagined a family that will be able to forgo buying a second car, and maybe, eventually, get rid of the first one.

What I saw underground was a city connecting more people. It will be worth the wait.