The suggestion is in response to the National Party’s election promise to increase speeds on some express ways to 110km/h, and Labour leader Chris Hipkins backtracking on the government’s road speed reduction programme.

"Given that most drivers don't keep to the designated road speeds on highways anyway, Waka Kotahi raising the permissible maximum speed from 100 km/h to 110 km/h on Transmission Gully and raising maximum speeds on other roads elsewhere around the country, not only will increase the severity of any accident when it occurs but will also lead to an increase in our transport emissions of greenhouse gases that we urgently need to decrease,” Sims said in response to a Carbon News query about the likely impact of increasing speed limits.

“Maybe Waka Kotahi should start a "Go Slow" campaign" for Kiwi drivers instead,” said Sims, who is professor emeritus sustainable energy and climate mitigation at Massey University.

Waka Kotahi recently told Sims in an Official Information Act request that it didn’t always carry out comprehensive emissions assessments when considering changes to speed limits, but that it had done one for the Hamilton Express Way.

Using a vehicle emissions prediction model, it estimated a 4.34% increase in greenhouse gas emissions for the Tamahere to Hampton Downs section of the express way if the speed limit increased from 100 to 110km/h.

Improvements in vehicle efficiency would see the increase drop to 3.77% by 2041.

Sims said increasing the speed limit to 110km/h on Transmission Gully - which at its steepest point has a gradient of about 8% - will result in a larger increase in emissions.

“It’s hard to assess the actual increase in emissions but I would guess that it's around 5% (trucks being different to cars and EVs different again - mine shows a fairly similar energy demand as if running  on the flat due to the regeneration when heading downhill).”

Cars all have an optimal speed range for limiting fuel consumption and it’s typically well below 110km/h - rising from about 80km/h partly as a result of increases in air resistance.

 Slowing down saves lives and reduces emissions

The government’s Road to Zero strategy - released in its first term - stated that about 87% of current speed limits are not appropriate for the condition of our roads.

“Reducing travel speeds across parts of the network is one of the most efficient and immediate things we could do to reduce trauma.

“Safer travel speeds will save lives. They also reduce the stress for other road users, including passengers, and help other people feel safe to walk, bike, or travel with children. Slower speeds can also reduce harmful emissions.”

However, this election has seen a U-turn in the direction of travel with both National and Labour promising to halt the speed reduction programme.

In March Chris Hipkins, in "policy bonfire," announced the speed reductions would now be limited to the most dangerous 1% of roads.

That’s despite a Waka Kotahi study showing that reducing the speed limit from 100km/h to 80km/h on the 76km Napier Taupo highway prevented 34 crashes in 12 months.

The reduction in speed limit resulted in an increase of journey times of between 36 seconds and 3.6 minutes.

The more things change….

Ten years ago today, Carbon News reported Sims saying that New Zealand was missing the opportunity to substantially cut our road emissions.

He said that cities in other countries were moving away from cars to mass transit and walking and cycling.

But in New Zealand everything “revolves around driving large cars and sitting around wasting time on congested roads.”

A decade on, Sims said little has changed.

In 2013 Carbon News reported that transport - including aviation - made up 18% of New Zealand’s total emissions profile.

The Ministry for the Environment’s just-released Our atmosphere and climate puts the figure at 17.9% of total emissions - 40% of CO2 emissions.

Back then, Sims said it would be possible to significantly reduce emissions by capitalising on changing social trends.

He pointed to improved public transport, the removal of cars from central cities, and improved cycling and walking infrastructure.

Car love an obstacle to progress

"The love for the car in New Zealand will no doubt decline, but many politicians seem to have no vision for that – for example the 'roads of significance to National' project is a classic example,” he said.

So how does Sims feel looking back on his comments from a decade ago?

“Seems we haven’t made much progress - although a few of the technologies I proposed then have occurred in some form.

“Cycleways have expanded in many towns and cities since then but there is still a local battle whenever new ones are proposed or developed.

“EVs, E-bikes and E-buses have taken off largely as predicted – I didn’t think of E-scooters!

“The love for the car continues and very few car-free streets have materialised – even though they are blossoming in many other countries – European region, South Korea, Japan etc in particular.

“The building of more roads has been a significant topic during the recent election debates  – but with both National and Labour aiming to invest billions of dollars in building more there seems little vision for now modes of transport of people and freight,” he said.

"Their policies to attract votes  confirms that the majority of Kiwis don’t want to get out of their cars – in spite of a greater realisation in the past few years that climate change impacts are happening and we all have to reduce our carbon footprints.

“We do have commercial and community-owned car fleets now, such as Mevo as well as E-scooter and cycle hire. So there’s been just a little progress there.

“We don’t have fuel emission standards but the “feebate” scheme has successfully encouraged the uptake of EVs and hybrids and more light rail is under construction in Auckland.

"In the past decade, high fuel consuming utes and SUVs have grown in popularity; car importers spend much more on advertising them than lower fuel emission vehicles; higher engine power and fast acceleration rates are still actively promoted;  there is an annoying trend towards driving standard vehicles but modified with loud exhausts, fast acceleration etc (how do they ever pass a WoF?); and congestion has become worse in most cities with congestion charges still only vaguely being talked about.”

“Overall our annual transport carbon emissions continue to rise – no doubt partly due to the higher population since 2013 – but also in spite of vehicle manufacturers aiming to produce more fuel efficient vehicles.

“So overall, my opening statement of 10 years ago holds. “New Zealand could substantially cut greenhouse emissions from transport but lacks the vision to do so”.

 “It’s time for me to cycle to the nearest polling station.”