(Photo by Jim O'Grady.)

(New York, NY - WNYC) Here's what will be converging tonight on the area around the new Barclays Center Arena in Brooklyn: rush hour crowds pouring onto and out of nine subway lines that sit beneath the intersection of three major thoroughfares; 19,000 ticket holders on their way to a sold-out Jay-Z concert; massive thunderstorms.

And another sign of a looming traffic-pocalyse: the guy hired to devise a traffic plan for the arena has issued a Gridlock Alert for the intersection of Flatbush and Atlantic Avenues, right where the Barclays Center sits. Traffic engineer Sam Schwartz, known as Gridlock Sam, says ticket holders headed to the 8 o'clock concert will swell the area's normally heavy rush hour.

The NY Metropolitan Transportation Authority is adding extra subway service on the Q and 4 lines in the form of “gap trains,” or trains held in reserve to respond to a surge of customers. And double the number of late-night Long Island Railroad trains will run after the show. These “game trains” will arrive every 15 minutes and hold about 1,000 passengers each.

City planners have been trying for months to discourage driving to Prospect Heights, Park Slope and Fort Greene--brownstone neighborhoods with tree-lined streets that surround the Barclays Center arena. They've taken steps like reducing the arena's parking spots from 1,000 to 541. They've also launched a pro-transit publicity blitz that got The Harlem Globetrotters, who'll be playing a game at The Barclays Center on October 7, to ride the rails with reporters.

(Photo courtesy of the NY MTA)

"I'm Big Easy of the world famous Harlem Globetrotters," said Big Easy two weeks ago, while standing on a train platform at a transit hub in Queens that city-bound riders of the Long Island Railroad use to switch to the subway. "We’re going to take a train to the Barclays Center."  And then he did. The trip took 20 minutes, which was faster than driving, with or without a Gridlock Alert.

But planners know not everyone will heed the call to take transit to Brooklyn Nets games and concerts by Barbra Streisand and Rush. That's why they hired Schwartz to come up with a plan that would, in his words, "intercept drivers before they approach the arena."

Schwartz is setting up half-priced lots with free shuttle buses up to a mile from the arena. Fans can also pay to reserve a parking spot online, which is supposed to cut down on drivers circling around in search of parking. And Nets tickets will feature mass transit directions but nothing about how to drive to the stadium or park a car. There will, however, be plenty of parking right at the arena's entrance ... for 400 bicycles.

Still, it's not hard to find doubters of the plan. Neighborhood resident Gib Veconi came to the center's symbolic ribbon-cutting last week in part to protest what he sees as a looming traffic disaster.  "If you're coming to park here, you can try to get into one of the 500 spaces down on the other block there for the arena," he said. "But if you can't, you're going to circle these streets looking for a free place to park--streets that are already jammed."

Will the near-nightly migration of tens of thousands of people to and from the Barclays Center Arena turn out to manageable or chaotic? Tonight is the first test.