NEW YORK — With performance halls shut because of the coronavirus pandemic, the best concert venue a violinist could hope for one recent October Friday was a sidewalk in the Bronx.

Fiona Simon tuned her instrument as she prepared for one of her only public performances with the New York Philharmonic in months.

The setting was a far cry from the orchestra's usual home at Manhattan's Lincoln Center. Traffic hummed and sirens wailed as a crew laid cables and unloaded speakers from the back of a double-parked pickup truck.

But Simon said the pop-up concert — one of several the Philharmonic has been playing around the city this fall — filled a need she's had since indoor performances stopped in March, depriving musicians of not just a paycheck, but a sense of purpose.

"You're not a complete musician if you're just playing for yourself," Simon said.

Simon, a native of England who joined the New York Philharmonic in 1985, says she has struggled to cope with not having an audience, sometimes performing for friends virtually over the phone.

"I think it's a fundamental human need," she said.

The Philharmonic came up with the idea for a series of outdoor, pop-up performances over the summer, even as it was forced to lay off or furlough nearly half its staff as it faced a multimillion-dollar budget deficit.

On that Friday, Simon and a few colleagues played three corners of the city as part of the series they're calling the NY Phil Bandwagon. The first show of the day was outside a Bronx school, the second outside a public library in Queens and the final one in a Brooklyn park.

The bandwagon itself — a red Ford pickup truck — rolls up to the curb carrying a sound system, music stands, lights and orange traffic cones to keep the audience socially distant. The musicians follow in a van.

The Philharmonic plans to hold its final Bandwagon concert of the year this weekend, and then resume the program in the spring.

New York's street life has always been vibrant, but these days, the city's outdoor spaces are more important than ever as many residents are stuck in small apartments working from home.

"There's this whole myth that New York is dying, but it's only dying in the places that were built for people not from New York — the people in New York are thriving," said Curtis Stewart, a Grammy-nominated violinist who joined for a guest performance with the Bandwagon.

As the group began its final performance of the day, countertenor Anthony Roth Costanzo kicked off the show from the bed of the truck.

"We're going to play you a little concert," he said as people began to linger in the warm glow of an early autumn sunset.

The set lasted 20 minutes. A trio of violins preformed well-known tunes from George Gershwin and Charlie Parker, as well as Henry Purcell's "Dido's Lament" — a sorrowful piece that Costanzo said "responds to the moment in a more emotional way."

As the audience swelled to dozens — couples, families, dogs and their owners — it became clear that the concert is as much an emotional outlet for the crowd as it is for the musicians.

"I think as we're closeted up in our homes dealing with the storm that is current events we need an outlet. We need a place to put our feelings, we need a place to feel safe," Stewart said. "You don't know what you've got until it's gone."