The $4.45 billion Second Avenue subway is a boon for business, increasing traffic at Upper East Side shops and restaurants by as much as 30 percent in its first year, a local merchants association said Saturday.

“The foot traffic has drastically increased,” said Sammy Musovic, head of the Second Avenue Merchants’ Association and owner of three restaurants on the avenue. “We’re getting tourism we never had before.”

Musovic said many businesses closed in the roughly nine years of construction, estimating a 30 percent vacancy rate while the line was built is now about 10 percent.

But now the neighborhood is bracing for rising rents that could push out businesses.

“They say it’s gonna be the next Madison Avenue,” Musovic mused. “The real estate prices are going up.”

The Second Avenue Subway took nearly 70 years to build. The first phase of the Q train extension brought three new stations to 72nd, 86th, and 96th Streets.