On May 26, in a project update posted on its website, Waka Kotahi said it believed that "people will experience between four to 11 minutes increase in journey time on State Highway 5".
Two methods were used for the recalculation.
Method 1 calculated the time difference between the current mean speed people are travelling than the proposed speed limit.
"This method assumes that where people are currently driving above 80km/h, they will now drive at 80km/h and where they are driving below 80km/h their speed will remain unchanged.
"The data we used when we first launched the consultation collected data over a two week period and broke it down into four similar sections. Applying method one to this data showed a very small increase of under a minute."
In the re-calculation of the likely impact on travel times, NZTA used a different data source, a longer period of three months and broke the corridor length into smaller segments of 2km which "better reflect the different typography of the road".
"Because of this we expected some variation in the outcome.
"Our additional analysis does have a different result.
"The more detailed data suggests the increase in travel time northbound will likely be about 3.5 minutes, and 4 minutes southbound.
Method 2 calculated the time difference between the posted speed limit and proposed speed limit.
"Based on the second methodology, the increase between the posted speed limit of 100km/h to proposed speed limit of 80km/h the increase would be just over 11 minutes for the entire proposed length of 76km.
"This method works on the assumption that people are driving at the posted (and proposed) speed limit over the entire length, including the very windy parts, of SH5."
Consultation closes at 11pm on Sunday.
