Metrolinx has approved a $55 million contract for 12 “clean” American-made diesel trains for the upcoming rail link between Union station and Pearson International Airport.

The provincial agency announced the deal with Sumitomo Corp. of America Friday. The new trains, which can be converted to electric, will create six two-car trains that can carry up to 120 people.

“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,” Metrolinx President and CEO Bruce McCuaig said in a statement Friday. “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.”

The air-rail link is expected to be completed in time for the Pan Am Games in 2015.

Metrolinx said the trains are new to North America and aren’t manufactured in Canada. The deal includes an option to purchase an additional six trains, potentially bumping the contract’s value to $75 million.

The provincial agency said it will work with Sumitomo to “optimize Canadian content.”

The Clean Train Coalition has been a vocal opponent of the Metrolinx plan to buy diesel. The group has been calling for electric trains.

NDP MPP Cheri DiNovo also opposes the diesel contract.

“The health concerns of tens of thousands of residents who live near the tracks have fallen on deaf ears” DiNovo said in a statement Friday.

“Despite all evidence to the contrary, despite strong community opposition, Metrolinx has voted to go ahead with this ill-considered plan.”

With files from the Canadian Press.