From stuff NZ: 

The $630 million Kapiti expressway has actually doubled the amount of time it takes to commute into Wellington during the morning rush, some motorists say.

One Kapiti Coast resident believes the morning crawl into the capital is now so bad that she is vowing to use the train instead, even though it will cost her $100 more a month. …

The problem is that while the new four-lane expressway between Mackays Crossing and Peka Peka has shaved minutes off the journey through the Kapiti Coast, it has also created a traffic bottleneck where it connects to the old two-lane State Highway 1, just north of Paekakariki.

The counter-argument, of course, will be that the problem can be solved with more widenings and roads.  Which is exactly the case here:

Neil Walker, the transport agency’s Wellington highways manager, acknowledged earlier this month that congestion at Mackays Crossing was likely to continue until the Transmission Gully motorway was built.