A decision to expand Selden CPZ in and around the Ham Road area was passed unanimously by the Worthing county local committee on September 16 last year.
The county council initially indicated that works would be completed by the end of 2015 or early January, but residents have now been told the zone will not appear until late March.
Ham Road resident Stuart Chalk said: “We’re really fed up, we just want to get it sorted, because for three and a half years, residents have struggled to park.
“The solution is there, but it just hasn’t been implemented.”
Jean Smith said her blind husband has huge problems crossing the road if they have to park on the opposite side of the road.
She explained they have been assigned a courtesy disabled bay which they will retain under the CPZ, but a space is not guarenteed.
She said: “Neither of our neighbours have cars so parking should be easy but it’s not.
“We have lived here over 40 years and the parking problem just gets worse and worse. Sometimes we feel trapped in our own home.”
Officers in charge of the project sent an email in early January to county councillor Roger Oakley explaining that ‘contractual and quality procedure checks’ had yet to be completed.
In the message, CPZ officer Miles Davey said they were unable to provide an accurate timescale, but they were keen to keep the public informed.
Cabinet member for Highways and Transport John O’Brien said the CPZ was a ‘work in progress’.
The CPZ extension is intended to restrict parking to residents with a permit. It will also prevent parking on pavements in narrow roads.
A letter from MP Tim Loughton mentioned the particular problems with congestion in Benedict Close and Archibald Road.
Parking has been an ongoing issue in the Ham Road area since 2012 when controlled parking was introduced in the surrounding roads.
Rail commuters, hospital workers and shoppers find the residential streets convenient places to park.
Following a petition in 2012, West Sussex County Council granted around 30 households a permit to park in the neighbouring streets.
A proposal to extend the CPZ was made in March 2015.
Councillor for Selden Keith Bickers said: “Local residents in East Worthing are becoming increasingly frustrated over the continuing delays to the implementation of the extended ‘Controlled Parking Zone’. Many have contacted me.
“Whilst some minor initial road marking has been started, there appears to be a lack of urgency on the part of WSCC to complete all the work.
“I acknowledge that this is a major project but this fact this does not, in my opinion, excuse WSCC for the delays. I hope that we will see positive signs of action very soon.”
A West Sussex County Council spokesman said: “The introduction or extension of a CPZ is often a complicated and lengthy process and the case of East Worthing is no different.
“We are now in the final stages of the process with the completion of the contract drawings expected in the very near future.
“These drawings are key to the project progressing smoothly. Although they have taken longer than first anticipated, it is right that time and care is taken.
“Once completed these drawings will be passed to the contractor who will then be able to produce a timeline for the project.
“We anticipate the project timeline will be available by the end of March 2016.”