Napier-Taupō Rd speed drop proposal: Travel time increase now up to 11 minutes, NZTA says

If a section of SH5 is lowered to a 80km/h speed limit, the additional travel time will be between 4-11 minutes, NZTA has re-calculated after originally saying it would be under a minute. Photo / Warren Buckland

Waka Kotahi now says the average travel time increase if an 83km section of the Napier-Taupō Rd were to be lowered to 80km/h would be between four and 11 minutes.

In April when Waka Kotahi NZ Transport Agency put the proposal out for public consultation it originally said the average travel time increase would be under a minute.

In a talking point published in Hawke's Bay Today on April 24, Waka Kotahi director of regional relationships Emma Speight wrote:

"Our technical assessment of the road found that although the posted speed limit on SH5 between Rangitaiki and Esk Valley is 100km/h, the mean speed that people travel at is 81km/h. This means lowering the speed to 80km/h will increase the average travel time by less than a minute."

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.