The New Zealand Transport Agency, police and contractors working on the Baypark to Bayfair Link say too many people are speeding through the area, putting lives at risk.
Agency project manager John McCarthy said not everyone was adhering to the 50km/h speed restriction through the site and there had been "a number of minor crashes through the site due to speeding and driver inattention".
"The temporary traffic management has narrowed lanes, providing less time to react to other vehicles, and a reduced speed is required to keep road users and workers safe."
Since August 2017 there have been 36 crashes within the Bay Link project site. Of those, 11 per cent of the crashes were a result of speed, and 75 per cent were a result of driver error, namely following too closely, failing to notice the car in front was slowing, and failing to give way.
McCarthy said due to the narrower lanes, the potential for both worker and motorists to be harmed was greater.