PITTSBURGH — Ever rush downtown to make dinner reservations or get to the theater on time only to be thwarted by “lot full” signs at every parking garage you pass? Now Pittsburghers will have a high-tech, real-time tool to help them find a parking space.

Starting Wednesday at noon, motorists can go online before they leave home, use a mobile device, or call a phone number to find out where there are parking spots available as part of a pilot program known as ParkPGH. The tool is being used at nine garages with 5,000 spaces in the city’s theater district, but officials with the Pittsburgh Cultural Trust say it could be rolled out across the city if it’s successful.

“I certainly think it will make one less excuse of why people won’t come out of their house on a cold winter night,” said Kevin McMahon, the Trust’s president and chief executive.

McMahon said about 2 million people visit the city’s theaters, restaurants and other attractions in the Cultural District annually, twice as many as a decade ago. Officials expect as many as 100,000 visitors downtown over the next few weeks for holiday shopping, the First Night celebration and the opening of Mary Poppins at the Benedum Center.

But as the numbers of downtown visitors has increased, so has the need to provide real-time parking information so that the stress of finding a spot doesn’t deter people from coming into the city, he said.

“We know from past comments that we received on a regular basis that parking is a very important part of the total experience,” McMahon said.

The system works through software that calculates the number of spaces available in the garages every 30 seconds. At the website, the number of open spaces will be listed next to a garage’s name along with a color: red means a garage is near capacity, yellow means approaching capacity, and green means there are available spaces.

McMahon said it was important to the Cultural Trust that anyone could use the space finder, even if they don’t have a computer. Besides parking information online, motorists can send a text message or call to check.

The program cost about $175,000 and officials worked with the Benter Foundation, Alco Parking, software developer Deeplocal, and Carnegie Mellon University’s Traffic21, a transportation research group, among others.

“I really think that one of the impediments to coming into town, not just for cultural events but for shopping, generally is this uncertainty about parking. I think it’s a psychological impediment that everybody feels who has to come into the city,” said Bill Benter, the Benter Foundation’s president.

Parking spot finder programs are in use in several cities, including San Francisco and Oakland, Calif., and many other countries have electronic signs that tell motorists how many parking spaces a lot has.

In the last five years, several companies have developed online tools to check for parking availability and in some cases even reserve spaces, such as San Francisco-based GottaPark and Streetline. At Massachusetts-based SpotScout, people can share information about available spaces on its website.

Rick Stafford, Traffic21’s director, said some of those new technologies work by putting sensors in parking spaces, which can be expensive. Instead, ParkPGH utilizes the gates already in place at local garages to help count cars coming in and out. And the program is free to use and doesn’t require users to register.