The campaign group has invited nine councillors to a public meeting on March 4 in the Civic Centre to discuss the proposed road scheme at Cuckoo Corner which threatens trees surrounding Priory Park.
Society Chairman Peter Walker said this would be the first opportunity for people to speak to councillors since the authority's preferred option was published in the Civic News.
He added: "It is really the council's job to arrange meetings like this, but at no time during their public consultation period have they actually spoken to the public."
The meeting date has been chosen to fall on the last day before councillors meet to make their decision whether to go ahead with the controversial road scheme.
Mr Walker added: "We expect a big turnout, so that people will be able to make absolutely certain that councillors are aware of the strength of feeling against the damage which would be done to the north side of Priory Park if this ill-thought out scheme goes ahead."
The nine councillors which will be attending the meeting are Ron Price, Anna Waite and Murray Foster from the Prittlewell Ward; Brian Houssart, Simon Gorham and Mike Dolby from St Laurence ward; and the three leaders of the main political parties.