The £10.9m scheme has been recommended for final approval at a meeting of North Yorkshire County Council' s executive and if given the go-ahead will lead to permanent changes to town centre streets with improved walking and cycling routes.
The aim is to create a more accessible and attractive Harrogate, but the plans have faced sustained opposition from some residents and businesses.
A 714-signature petition calling for the project to be halted was recently rejected by the council, while the leaders of three business groups have claimed their concerns have been "continually ignored".
Harrogate BID, Harrogate District Chamber of Commerce and Independent Harrogate have also called for a delay on tomorrow's vote until they have studied an economic impact report which they claim they were only made aware of last week.
The groups said in a joint letter to the council: "We are told the project will encourage those who live close to the town centre to leave the car at home and travel in by bus, bicycle or on foot.
"What it fails to do is take into account those tens-of-thousands of visitors who live outside the district, and choose to come here to stay in our hotels and guest houses, and spend their money in our shops, restaurants, bars and entertainment venues."
The most controversial parts of the project include making Station Parade one-lane traffic and a part-time pedestrianisation of James Street.
Also proposed are upgraded junctions, more cycle lanes and improvements to Station Square, as well as the One Arch underpass.
If approved, construction works could begin in Spring.
The proposals are being funded by the government's Transforming Cities Fund, with similar projects being brought forward for Selby and Skipton.
Councillor Don Mackenzie, executive member for access at North Yorkshire County Council, said the investment was the biggest in the towns "in decades" and would deliver an economic boost "by making it quicker, easier and safer for people to travel".
He said: "We want to encourage more people to travel by foot, bike and public transport because it is good for health and the environment by promoting fitness and reducing congestion.
“The entire project is a great example of partnership working between Craven District Council, Harrogate Borough Council, Selby District Council, North Yorkshire County Council and the West Yorkshire Combined Authority and is set to deliver real benefits to residents and businesses across our county.
"We have listened to feedback from the public consultations and are confident people will be pleased with the results.”
Tomorrow's meeting is being held remotely and will be available to view on the county council's YouTube channel from 11am.
By Jacob Webster, Local Democracy Reporter