Mulcair told the Federation of Canadian Municipalities convention in Edmonton Saturday that an NDP government would provide an extra $1.5 billion each year for roads, bridges and other infrastructure through the existing gas tax by the end of its first term.
He also promised an NDP transit plan would see $1.3 billion invested each year over 20 years, and said there will be incentives for the construction 10,000 affordable homes.
Liberal Leader Justin Trudeau also promised more money when he spoke at the convention on Friday.
But Mulcair said successive Liberal and Conservative governments have made empty promises and failed to make a dent in what he called "Canada's infrastructure deficit."
"The fact is, the gas tax transfer is one of the best tools available to help cities with their long-term needs," Mulcair told the FCM conference on Saturday.
"That's why (former NDP leader) Jack Layton pushed so hard for the gas tax transfer when he was FCM president. And that's why an NDP government will actually get it done."
Trudeau told the conference his plan focused on affordable housing, transit and infrastructure, better technology, and helping cities adapt to extreme weather catastrophes caused by global warming.
Finance Minister Joe Oliver reacted to Trudeau's pledges with questions about how he planned to pay for them.
Mulcair didn't explain exactly where the extra money for transit would come from, but noted that the former Liberal minority government in 2005 earmarked $4.5 billion for corporate tax cuts. He said the NDP at the time proposed spending it on housing, transit and post-secondary education.
"That's us. That's the NDP. You know us. Those are our priorities," Mulcair said.
Mulcair also announced on Saturday that an NDP government would change income tax rules to allow people who are already investing in rental housing to have an investment incentive that would allow them to take out their investment without being penalized by a capital gains tax, provided they are going to being investing in new and more affordable rental housing.
He said he's already promised the NDP will sustain commitments to social housing agreements that are set to expire.
New Democrat MP Matthew Kellway, who represents a Toronto riding, said after Mulcair's speech that the promises are affordable
"All of this is fully-costed by our party," Kellway said. "We're not putting out things we can't pay for."
George Smith, a party spokesman, said Mulcair's time in Alberta would include a visit with the province's new NDP premier, Rachel Notley.
The NDP swept to power in last month's Alberta election.