The cost of building a subway to replace the rapidly aging Scarborough Rapid Transit (SRT) line is a subject of some controversy — and a big price difference — at city hall.

City council and the TTC say it would cost about $2.3 billion to complete the project — that's $500 million more than the predicted price tag of $1.8 billion to change the SRT into an above ground light rail system, or LRT.

The $1.8 billion cost would be covered by the provincial government agency, Metrolinx. 

But Metrolinx says any additional cost would have to be covered by the city — and it further says the cost would be nearly double what the TTC says — $923 million.

And that is where the two sides stood when they met on Tuesday.

TTC commissioner Josh Colle — who is also a Scarborough councillor — says when it comes to plans for the Scarborough SRT the city has been clear.

"They [Metrolinx] are seeking our comment again on the extension of the Bloor-Danforth line, which I had assumed we had already done," said Colle.

But the binding master agreement signed by the city and province calls for the  Scarborough SRT to be converted to an LRT. A few months later council asked Metrolinx to explore a subway option.

"From a network planning perspective this is a better transit option for people of Scarborough," said Coun. Peter Milczyn. 

But Metrolinx CEO Bruce McCuaig says if the city wants a subway, instead of an LRT, then the "city has to pay to operate and build a subway." 

"Realistically it is not something Metrolinx could operate and own. So if it is a subway then I think our belief is that would become the responsibility of the city and the TTC," he said.

Metrolinx says council has to reaffirm its commitment to an LRT or work will be stopped on the project on Aug. 2.

"I find it curious because all along they [Metrolinx] have said to us it's their project and their money — and they'll do what they're going to to do. And the transportation minister came out quite clearly saying that. We [city council] felt it was in our prerogative to give our advice and ask for their opinion on these matters — and we did that at council," said Colle.

Longtime Scarborough politician Coun. Norm Kelly says the fight is far from over. 

"In Scarborough, subways and rapid transit will be the issue, so it ain't going away ... in this case [the issue won't be] over until the 2014 election." 

Tuesday's meeting between the TTC and Metrolinx did not produce a solution.

McCuaig said there will be more meetings in the future to iron out the problems.