A 12-year campaign to get lights at the busy Anita Street intersection at Redland Bay came to an end on Thursday, when Transport Minister Scott Emerson committed to an overhaul.
Mr Emerson announced the road project when he met LNP candidate for the seat of Redlands Matt McEachan and mayor Karen Williams.
He said the project, expected to cost about $2 million, would be funded from "savings" but would only occur if the LNP was returned to government.
Planning was expected to start this week.
But a row broke out over funding the last-minute LNP election promise.
Long-time campaigner for the T-intersection upgrade Leeann Lillicrap said the promise was nothing more than vote buying.
Ms Lillicrap said residents were wary about any new promises after the LNP scrapped a Labor pledge of $1.1 million following the 2012 election.
"Many feel they were lied to after the plans for the lights were scrapped and the allocated funds withdrawn so why would we believe the LNP now?" she said.
"If it has been approved and found to be necessary for safety reasons and the money is there, the work should be carried out regardless of who wins the election.
"The LNP said last year they would not spend any money on Cleveland-Redland Bay Road until 2025 and now they have done a backflip, everyone is confused and angry."
Ms Lillicrap said she wanted designs to include moving the entrance to a truck yard opposite Anita Street.
Mr Emerson declined to comment on the truck driveway, which was the subject of a long-running court case.
He also refused to comment on when the rest of Cleveland-Redland Bay Road would be upgraded to dual lanes but said the traffic impacts of any residential housing project would be assessed before road improvements.
Mr McEachan said he chose the intersection as an election project after listening to complaints about the road for more than eight years.
Independent candidate for the seat Sheena Hewlett said the announcement was a hollow promise as developer Fox and Bell already included the intersection upgrade in plans for its Shoreline housing estate.
"The $2 million project has not been budgeted for and is not included in Forward Estimates," Mrs Hewlett said.
While in the Redlands electorate, Mr Emerson ruled out abolishing the $1 million a year Translink levy taxed on bay island ratepayers.
