Rozelle Interchange was meant to ease congestion on Sydney roads. So what went wrong?

It's a multi-billion-dollar missing link that's part of Australia's largest road project, billed as one of the nation's most complex.

But your commute may have blown out this week, especially for those in the inner west Sydney suburbs like Rozelle, Haberfield, Balmain, or Annandale, after the opening of the Rozelle Interchange.

It's all largely thanks to a couple of small sections of roads where bulk traffic now needs to merge down to single lanes as they approach the city-bound entries to the Anzac Bridge.

The two main trouble spots are along the City West Link as you pass Annandale and Victoria Road as you pass Balmain.

The bottlenecks have made the trip out of Balmain towards the city particularly painful for residents who have few alternative options.

The situation even wiped the smile off the face of comic actor Rebel Wilson.

"Thanks Rozelle Interchange for now making a 15 minute trip into the city 90 minutes via Victoria Road — WTF," she wrote on social media.

Welcome to Sydney's much-discussed "spaghetti junction".

Or more specifically the fight to get in it, out of it, or around it.

Late on Thursday, Chief Operations Officer of Transport for NSW, Howard Collins, was pleading for patience and said "all options" were on the table to fix the congestion.

What was it built for?

The Rozelle Interchange is a complex road connector made up of 24 kilometres of twisting tunnels and features a dozen entries and exits.

Part of it is tolled.

Its purpose is to ease congestion and significantly reduce travel time for commuters.

To do that, it connects to the M4-M8 Link Tunnels, the City West Link, and provides an underground bypass of Victoria Road between Iron Cove Bridge and Anzac Bridge.

It will eventually connect to the future Western Harbour Tunnel once that project is complete.

After almost a week in operation, Sydneysiders have experienced significant delays — some close to an hour.

What went wrong this week?

Before its opening on Sunday, November 19, drivers were assured navigating the complex network would be as simple as following signs.

Transport figures also foreshadowed traffic would get worse before it got better.

But little was said about the approaches and exits to the interchange.

Each day, motorists have faced gruelling delays with trips often taking three times as long as usual.

Mr Collins said things appeared to improve as the week wore on.

Motorists did not appear to be as enthused, but Mr Collins assured people he was listening, learning, and working "24/7" with other executives to find appropriate fixes.

"I want to give people assurance that nothing is being left unturned when it comes to options and even as we speak, our engineers are considering what can be done to improve the situation."

Will things get better?

One option being considered is to increase traffic light metering on the approach to the Anzac Bridge.

For people who live close to the City West Link, Mr Collins suggested taking alternative routes such as Parramatta Road — a street that was this year crowned as the state's worst.

"So if you're a local and live in Glebe or Annandale or Leichhardt, go south rather than north and you might find that you get into the city quicker," Mr Collins advised.

For people who live in areas along Victoria Road, like Balmain, the solutions appear less obvious but include manipulating traffic lights and ensuring vehicles don't drive in bus lanes.

"It goes from 10 lanes into four," Mr Collins said of the city-bound approach to the Anzac Bridge.

"We used to have seven lanes into four. We're now dealing with the fact we've got the motorway traffic coming through as well as the old-fashioned City West Link and the Victoria Road."

Peter Khoury, the head of media for the NRMA, said the group publicly raised concerns about plans to reduce major thoroughfares to single lanes on the approach to the Anzac Bridge.

Mr Khoury also wants the government to release the modelling used to determine the new interchange and how drivers would use it.

He worried some of the problems, especially the approach to the bridge, appear to be structural and if not fixed would simply shift congestion and potentially worsen already woeful areas.

"We've conducted research of our members … the research showed that outside of the CBD, the inner west is considered to be the most congested part of Sydney," Mr Khoury said.

"I mean this is a critical part of Sydney."

Then there are more basic concerns.

"It is increasingly frustrating when we are having to say the same thing over and over again," Mr Khoury lamented.

"You need to have a toll-free period."

Toll-free periods were introduced by the government in 2005 following the failed Cross City Motorway.

However, the policy was dropped by the previous government and has not been reintroduced, despite the rising cost of living.

The government has repeatedly said it would not give in to public pressure and allow a toll-free grace period.

He has urged policymakers to read the recommendations of a review into the disastrous opening of the Cross City Motorway in the early 00s to ensure mistakes of the past are not repeated.

Where to from here?

It's not only structural concerns being raised — communication has also been criticised.

One communication and road safety expert said she was frustrated to see road users being blamed for some of the issues.

"The public unfortunately is seen to be the diabolical naughty people in all this and it's not the road user, it's the way it's designed," Emeritus Professor Ann Williamson with UNSW's School of Aviation, Transport and Road Safety Research Centre said.

Part of the complication, she believed, was poorly placed signage.

"When you've been doing the same things the same way for years and years and years … to suddenly change it with a sign at the point in which the decision needs to be made — you're just asking for problems," Professor Williamson said.

"No wonder people are getting it confused."

She's also scathing of Transport for NSW's handling of the situation, accusing the transport body of "dropping the ball".

"This is usability 101 but unfortunately, Transport for NSW doesn't seem to have done that course and they need to," Professor Williamson said.

In the future, she said transport authorities needed to carry out far more usability testing, where roads are open to a small number of naive road users who report back on what worked and what did not well before the road opens to the public.