The four leading candidates to become mayor of Montreal squared off Monday evening in what was, for most of them, the second-straight night of debating each other.

Richard Bergeron, Denis Coderre, Marcel Coté and Melanie Joly discussed their visions for transportation, the environment, and the proposed plan to turn the St. Michel quarry into a composting site.

The Projet Montreal plan, spearheaded by Bergeron, is the most ambitious. He proposes to build a billion-dollar tramway throughout the city, especially in the highly developed downtown core and near-urban areas.

Coté said a tramway is an expensive project that Montreal cannot afford.

"There were some sharp difference on whether we should have tramways in Montreal or not," said Coté.

He, along with Coderre both prefer adding reserved bus lanes and bike paths, while Joly said her plan is different.

She's calling for 130 km of express bus routes.

"That would basically be a new surface metro and its eight times less than a tram, 40 times less than a metro," said Joly.

Coderre is widely seen as the frontrunner in the race and he frequently came under attack during the debate.

Bergeron said, given Coderre has many former members of Union Montreal in his party, that it is hypocritical for Coderre to now oppose the composting plan.

"These people that voted for [the plan] a few months ago are now against. Why? Just because they want to be re-elected!" accused Bergeron.

Coderre said that after talking with people who live near the former quarry, much of which is now a park, he will stop the plan if elected.

"You have to listen to your citizens. The issue of St Michel, my job my role it is to make sure I will be their spokesperson," said Coderre.

He pledged that the city would compost, just in a different location. Under the current proposal there will be four compost sites across the island.