The new trains will be operational by 2015. (Courtesy Metrolinx)

The board of Metrolinx on Friday approved the purchase of special trains to carry travellers between Union Station in downtown Toronto to Pearson International Airport.

The contract with Sumitomo Corp. of America for 12 of the train cars is worth about $55 million.

Metrolinx says the 12 units will create six two-car trains capable of carrying 120 people.

The contract would include an option to buy an additional six vehicles, which would increase its value to $75 million.

Metrolinx says the vehicles are new to North America and are not made in Canada. They will be made in the United States, but where possible, Metrolinx will work with the manufacturer to optimize Canadian content.

Metrolinx says the service will be operational by 2015 and offer an alternative to the five million car trips that take place every year between Union Station and Pearson Airport.

"We are excited to be taking the next step towards providing a link from the busiest airport to the busiest passenger rail hub in Canada," said Bruce McCuaig, president and CEO of Metrolinx.

"This rail link is a vital transit service for the Greater Toronto and Hamilton Area, improving traffic congestion and providing passengers with more travel options across the region."

But Cheri DiNovo, the provincial NDP's transit critic, said there is "strong community opposition" to the plan, due to environmental and health concerns of those who live near the tracks.

"The health concerns of tens of thousands of residents who live near the tracks have fallen on deaf ears," DiNovo said.