Residents living near the Maze site fear a week of traffic chaos as the Balmoral Show is held at its new home for the first time.
MLA Basil McCrea said people are apprehensive of the impact that tens of thousands of visitors to Balmoral Park will have when it starts on Wednesday.
"The roads are clearly not designed for anything other than residential traffic. My guess is that there will be traffic congestion at some times on the roads," he said.
The three-day agricultural show opens on part of the site of the former prison near Lisburn on Wednesday in a historic move away from its traditional home at the King's Hall in south Belfast.
More than 70,000 visitors travel to the Show each year from all over Northern Ireland. With the planned roads infrastructure and motorway link yet to be built, residents fear the volume of traffic could trap them if current infrastructure can't cope.
One Culcavy resident said: "All the talk in the neighbourhood has been about the traffic chaos the Balmoral Show will bring.
"The suspicion is that everyone will park in ours and neighbouring estates, making access to and from our homes a nightmare. We could be trapped in our own homes."
Meanwhile, a commuter who travels along the Halftown Road on his way to work said the congestion on the narrow back roads is already a problem at rush hour.
"The junction with the A3 is already a very busy junction with work traffic backing up along the Halftown Road. Imagine if you have thousands more people coming in. The roads round here can't take it – they already have really long queues.
"They need to think very seriously about doing something to the traffic signalling for those couple of days as it's a long wait if you're going onto the A3.
"It doesn't take a genius to work out that if you add thousands more cars coming into that, it's going to be chaos. You have a lot of people coming in from the Blaris Road. They have to go across the road if they're going home along the Blaris Road, so they have to turn right across the traffic and that means the traffic is going to back up."
DUP MLA Jonathan Craig said the Water Service had been planning to lay new sewage mains along the Culcavy Road during the week of the Balmoral Show.
The Regional Development Minister had to step in to make sure it would be rescheduled, he said.
"The traffic system is going to have to take time to bed in.
"The secret to this will be to get people in and get them parked as quickly as possible – that is key to making sure there isn't traffic mayhem," he said.
Mr Craig said it is likely that a planning application will soon be lodged for the roads infrastructure but it is likely to take several years before the link is completed.
"I would urge people to follow the signs and be patient. This is our first attempt at holding it at the Maze site and we hope everybody has an enjoyable day."
Mr McCrea said: "The bottom line is that we are anticipating a lot of traffic to the show, and there will be an impact on local residents. We've been round to talk to as many people in the Culcavy area as possible to explain to them what the arrangements are.
"The Balmoral Show people are confident that all the queueing will take place within the Maze grounds because it is such a large site. People are generally supportive of the Show coming but concerned about the impact. No-one really knows how the traffic management is going to work.
"We won't know until we see what it's like on the day – we don't know how many people will come on the day."
Organisers, The Royal Ulster Agricultural Society, urged people to leave plenty of time for their journey, follow directions of the PSNI and consider using public transport if possible.
Inspector Rosie Leech from the PSNI's Roads Policing Unit said: "We would ask motorists to allow plenty of time for their journey to and from the venue. Bear in mind that the M1 motorway at Balmoral is usually extremely busy all day during an event such as the Balmoral Show so use an alternative route if you can. Also, try to avoid arriving or leaving during the morning or evening rush hour when traffic is at its peak everywhere."