The AA is calling for some of the newly built motorways to get a speed limit increase to 110kph. Stuff reports:

Speed limits should be bumped up to 110kmh on the newest and safest roads, the Automobile Association says – and the Government is not ruling out the idea.

The suggestion comes as the Government announces it will review speed limits up and down the country over the next three years as part of its Safer Journeys action plan.

Associate Transport Minister Michael Woodhouse would not rule out increasing the 100kmh maximum speed limit as part of the review, but he felt such a move was unlikely to happen soon. Police say they are open to discussion.

AA motoring affairs general manager Mike Noon said nudging up the speed limit by 10kmh on some roads could reduce congestion and improve productivity by ensuring the quicker movement of freight.

The type of road best suited to a 110kmh limit would be divided, four-lane motorways that have been built to KiwiRap four-star status, such as the northern gateway toll road north of Auckland.

It’s an interesting question,. Certainly driving on many of the newer sections of motorway, like the section along Hobsonville, you have to be very mindful that the speedo doesn’t creep up but I’m not sure that instantly equates to us needing a higher speed limit. The comments from the AA also raise another interesting aspect to this discussion and that is an economic one. As pointed out in this post a few weeks ago, we currently value congestion based on comparing the speed you can travel in free flow conditions vs congested conditions. However new research suggests that a better way of judging it is based on the maximum capacity of the road. Using the existing methods would likely see some of the RoNS perform better in economic tests, when using the capacity measurement would see the opposite.

The freight argument is also a bit silly, as we know most freight is moved by trucks, which are governed by a 90kph speed limit (how many stick to that?). Increasing the speed limit for cars to 110kph is unlikely to see freight benefiting much.

But even if the government did agree to this request, it seems that it would only effect a very small number of roads:

The KiwiRap road assessment programme hands out star ratings to state highways, with five stars being top quality and one star being extremely risky. At present, there are no highways at either extreme.

Four-star highways are generally wide, flat and have a median barrier. Only 5 per cent of all roads fall into this category.

Of those, 64 per cent are in the Auckland region and 36 per cent in the Wellington region.

Most of SH1 from Wellington to Porirua, and SH2 from Wellington to Upper Hutt have a four-star rating.

About 28 per cent of all vehicle kilometres travelled each year is on four-star roads.

Mr Noon said increasing the maximum speed limit would be suitable for only a small amount of roads.

“The reality is that, if a vehicle is going faster and if it is involved in a crash, then physics says the outcome will be more severe.”

I know that there will be a lot of views on this either way but if it did end up going ahead, perhaps as a trade off, the opportunity should be taken to lower the speed limit of local roads at the same time.

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  1. Oteha Valley Rd to Silverdale is probably another candidate. Though remember police tend to only ticket at 11 kph over limit now and I’m not sure whether an “effective” limit of 120 is that safe. Kinda undermines all those “the faster you go the bigger the mess” campaigns too.

  2. Fuel usage will go up. Driving will be more stressful and exclude some people. (I wouldn’t drive on a German autobahn or an Italian autostrada, and the UK motorways I found scary too). It would be more unpleasant and unsafe to cycle on highway shoulders.

    Still if there was a matching call for reducing speed limits where they are presently too high, and a reduction in the police’s 11kph leeway into a more sensible 4kph leeway, plus some more electronic enforcement, then maybe it’d be ok (but only on motorways, not highways).

    Most NZ motorways are in or close to cities and have reasonably heavy traffic already, so it can’t be that smart an idea. Generally I think this is the AA having too much political power.

    1. Well, as I read it the AA only wants the limit increased on motorways, where you aren’t allowed to cycle.

      But I agree, it’s a bit silly to raise the limit on the motorway when most of the time you can’t even go 100, let alone 110.

    2. Matt, fuel consumption relates more to constant speed than to the speed limit, so another 10km/h won’t make much difference (some tiny difference perhaps, but that’s up to the driver’s economic decision). Just read Ben’s comment below and agree re the optimum revs; usually you’re in top gear at motorway speed.

      I don’t have a problem with reduced speed limits in relatively unsafe areas, provided we don’t go crazy like in parts of Australia where the speed limit sometimes changes every few hundred metres – undoubtedly a revenue-gathering exercise, not a safety matter.

    3. I find it stressful keeping under a speed limit that is very slow when compared to similar motorways in other countries. I think 130 is a reasonable speed on a clear section of motorway, and 120-130 is typically the speed limit in most European countries.

      The thing about motorways is that there is always an alternate non-motorway route available. If you don’t like traveling at European speeds in Europe, then you can take the parallel non-motorway route. That is likely to have driveways, have children on bikes, go through the center of villages, have lots of intersections and turning traffic, lack center barriers, and I have no idea why you’d find that less stressful. But each to his or her own.

  3. This would bring us into line with Queensland if such a thing were to happen.
    The Pacific Motorway along the Gold Coast and the Bruce Highway north of Brisbane (more to the point Caboolture) are both 110km/h and trucks are allowed to 100km/h on those stretches of highway. As a trade off Queensland have a rule of “50km/h in Built up Areas unless signed” in which you would find most 4 lane arterial roads at 60km/h, 2 lane arterials at 50km/h and local roads one by one dropping down to what is called a 40km/h Area which means a whole sub division outside of its main feeder road is down to 40km/h and you are expected to give way to pedestrians and cyclists as a courtesy. Queensland also has the 40km/h school zone too.

    Now as an enforcement measure the police are extremely brutal in enforcement. I go 4 km/h over ANY limit expect me to cop a AUD$150 fine and 3 demerit points out of a maximum of 12. Piss the cop off and expect a dangerous driving charge and lose your licence to boot. Go 10km/h over and expect $400 and 6 demerit points out of a maximum of 12. And if a speed camera catches you – the demerit points apply as well

    Admittedly Queensland is not have a great time with its road toll at the moment. However a reason was found and it was not the Aussie drivers. Try Kiwi drivers from Kiwi land who couldn’t drive back home now being let loose in Queensland and unable to cope. But hey who am I to get in the way of a good pub story 😉

    As for fuel economy: cars have two zones of optimal fuel economy. One usually at low speed cruising of 60km/h, the other depending on engine size at high speed cruising at 100-110km/h or wherever you tech meter sits at around 2200-2500rpm

      1. I don’t think that went ahead in the end. I know it got a bit of media attention a few years ago, however I quote from the NZTA web page ” Demerit points are given for some traffic offences and for speeding infringements (except those recorded by a speed camera).”

      2. By here do you mean New Zealand? Demerit points aren’t issued for speed camera fines, and while I don’t know what the government may be planning it hasn’t announced that’s going to change.

        There’s a few obvious problems – you can have anyone as the registered owner of a car, so how do you deal with company cars, or cars owned by people without licences? Those may seem like unusual cases, but people with close to 100 points are going to be pretty motivated to get the car in someone else’s name.

        1. easy – the person in charge of the vehicle recieves the demerit points just as happens with the fines. He must prove he wasn’t the driver of the car which is easy as all companies are supposed to keep a vehicle log. Although this rearly happens most people will and do keep a registar of who has their company vehicle so the can distribute fines as needed. Needless to say if the person using the vehicle doesn’t own up to the fine he prob wont have a job anymore.

          Car owner suffers, so if they take registration of the car they suffer the fines, if they don’t have licience they could end up back in court. So probably motivation to make whoever own up or not lend out car.

          I’m suprised that it hasen’t been implemented, I’m sure I saw company documents describing the new law and why vehicle logs are important for tracking who is using vehicles. In our company contracts it even states that if you have a company car you are responsible for paying fines and demerit points from speed cameras.

  4. If the aim of the game is to have more people die on our roads, then yep pop it up.

    As it is though I see nothing wrong with the current top speed.

  5. Stupid idea. Speed kills. Most people have crappy reaction times, are following too closely and are doing 110 anyway. any productivity improvements are very quickly wiped out by preventable speed related accidents.

    1. Surely it’s “following too closely” that kills, not the speed. What is safer, travelling at 105 with 0.5s following time (like many kiwis drive), or driving at 130 with 2-3s following time.

      How about some following distance cameras, instead of more speed cameras?

      1. “How about some following distance cameras, instead of more speed cameras?”

        So how do we get these, if we instead focus on appeasing the “I want to go faster!” folks instead? This is not about safety. This is about the petrolheads in our society chafing at restrictions, whether sensible or not.

  6. “…the opportunity should be taken to lower the speed limit of local roads at the same time.”

    Hesitate a little on that. By how much do you want to slow down suburban bus services?

  7. “Hesitate a little on that. By how much do you want to slow down suburban bus services?”

    Ummm, they will be affected almost not at all? Bus service times are primarily affected by dwell time at stops when people baord – and by congestion. Not by speed limits. And this isn’t talking about lowering Dominion Road from 50 to 20 km/h, this is about stuff like ensuring that Ian McKinnon Drive just further north is lowered from 60 km/h to 50 km/h. It used to be 70!

  8. Better to lower the speed limit on local roads from 50 to 40 rather than try to up the limit on motorways.

  9. Drivers hereare too shit. You would need to enforce keep left unless passing for this to bevaguely safe.

  10. I don’t see a problem with increasing the speed limit. However, a few other laws need to come into action at the same time IF they were to do this:

    1) No passing on the inside.

    2) Keep left unless overtaking.

    3) Law to allow people to merge onto the motorway so that people don’t take the “ME FIRST RARR” route and cutting people off while they are trying to merge into the motorway.

    4) No lorries/trucks in the far right lane.

    5) Not a law, but still something that should be done. You need to encourage courtesy and allow people who are signalling to change lanes. I think this in particular was one of my worst experiences whilst driving in NZ for 7 years. In Sweden and the UK (the two other countries I’ve driven in) I found that people were far more willing to allow people to change lane and keep safe following distances compared to NZ.

    There isn’t really a big problem with speed on motorways (Germany manages to have safer roads than NZ) and Sweden allows 110 on motorways and has the safest roads in the world. What matters is driver attitude and other laws to ensure smooth traffic flow and safe roads. Increasing speed alone won’t achieve anything.

    1. Defo. get the trucks outta the outside lanes – even the cops can’t figure that one out. 110 on the m-way past Drury in the south and Westgate in the West etc for sure. At 100kph you feel like you’re in suspended animation on that Southern mway stretch through to the Mumbais. Also, congestion in AKL would also be eased a little by better driving – e.g. if people moved promptly and drove like they were driving and not in some daydream…

  11. Personally, I think increasing speed limits to 110 on some of our new motorways should be totally safe.

    However, its absolutely the wrong thing to prioritise our time and effort on. We have so many road safety and transport inefficiency issues in this country. Some drivers chafing a little because their beamer can go a lot faster than 100 km/h shouldn’t be worth concentrating on! And it sets a bad precedent for calls to up speeds elsewhere.

  12. Related question,
    Why is the speed limit on the CMJ still 80 k/hr when the road works have all finished and there should be no reason for a lower limit.
    Surely the new Viaduct, VPJ and the roads between were all 100 kph roads when they were upgraded so why the need to keep the 80 limit still?

    As for the other idea, higher speeds mean worse crashes, but every one now travels at 100+ anyway, this is like the drinking age change, you have to couple changes with tough enforcement or you’ll end up with people going 120kph by default, which is not whats intended.

    Lastly all for a better way to measure travel savings, congestion is not really working is it, especially when you the crazy modelling coming out of the 30 year Integrated Transport Plan showing mid morning peaks worse than the AM peak.
    And thats surely because of the way you define congestion.

    I think of a road as pipe, So that you should measure the output based on the maximum capacity, not a velocity of the liquid through the pipe when its full versus when its not which is not actually measuring the correct thing.

    1. From what I remember the limit will stay at 80 kph as NZTA say the on and off ramps are too close in the CMJ so 100 kph is not safe. I will see if I can find the reference for this

    2. Frequent congestion, tight turns, very short on and off ramps frequent lane changes, less than simple road layout.

      Also, I am pretty sure that road tunnels in NZ have a max speed of 80 km/h, I may be wrong on this though.

    1. My vehicle runs more efficiently (less fuel per km) at 120km/hr than it does at 100km/hr. Less emissions per km. However I guess every vehicle is different in this respect. It should only be implemented on roads that pass the safety checks, when it comes to motorways lower speed doesn’t always make it safer or more efficient.

      1. What sort of mystery vehicle is this you are driving and how did you do your testing.

        I know for my sports car that I got amazing fuel efficiency driving at 70km/h. I tested that with a 300km long trip using a space saver. Compared to extensive testing at 100 & 110km/h.

      2. Joshua laws of physics say that isn’t possible; air resistance means a doubling of speed requires quadratic increases in power. From Wiki:

        A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power. It’s important to value the rolling resistance in relation to the drag force.

        Hey and check out the Reynolds Number!

        Your car is marketing its itself to you, going faster in a petrol car cannot save the planet.

        1. Your forgeting about gearing! Your gearing ratio is what determines your fuel consumption at different speeds. You vehicle will have two main optimal speeds, usually around 60km/hr and 110km/hr. Dan’s sport car would probably be around 70km/hr and 120-130km/hr optimal speeds. Yes simplisity would say the faster you go the more power required, however it’s a bit more complicated than this.

          Anyway more you need to spin those disc’s in your car the more fuel you will use, e.g if you are in 3rd gear at 3300rpm you will use more fuel than it you are in 4th gear at 2200rpm at the same speed! From memory I think 2200rpm is close to the optimal could be lower than that though. Wind resistance is actually minimal when comparing, although I do agree going 60km/hr will save more than going 110km/hr, I disagree going 100km/hr will save more than going 110km/hr, depending on the gearing of your car, sometimes you would.

          In the end most of your fuel consumption is most likely to come from acceleration which happens more when in the lower speed zones of 50-60km/hr. So I save more going 110km/hr, but worked out my car saves most at 120km/hr by testing on the open road. Yes thats breaking the law but it was in the pursuit of education! I found it out by getting to my cars optimal rpm and observing my fuel consumption gauge I have on my dashboard.

          In the end if I was trying to save the world I would be leaving my car at home, I dont nessarily agree with all the climate change avocates however I do agree with the health issues caused by emissions in our cities.Hense when I commute I take PT, when I want to have some fun or go out of town I take my car.

        2. “Your gearing ratio is what determines your fuel consumption at different speeds”

          The context of the discussion is a mooted increase in speed limit from 100 km/h to 110 km/h. At those speeds atmospheric drag dwarfs rolling resistance, pumping losses in the engine and frictional losses in the drivetrain. On that basis stating that it is gearing that determines fuel consumption is nonsensical. If your instrumentation indicates that you get better fuel economy at a steady 120 km/h that at a steady 100 km/h given equal road, gear selection and weather conditions then your instruments are incorrect.

        3. I try to believe you that your car behaves that way. But it will be a very rare scenario. Probably valid only for big displacement low revving engines on slip streamed vehicles (ford-holden kind of stuff). The big majority of cars will be more efficient at 80km/h and getting MUCH worse from there. Also correct tyre pressure will make a big difference and I think people don’t check that very often. My motorbike for example in the same gear does 3.5L/100km at 60km/h up to 4.5L/100km at 95 and then starts being scarily thirsty, but in the fun range I don’t care anymore. You should ride a naked bike one day to feel first person on your body the HUGE difference in wind resistance between 95 and 110km/h.

        4. Actually it’s the throttle position that governs the amount of fuel you use and not just the RPM on its own. You can drive at the same speed using different gears to get different RPMs at different throttle positions but ultimately it’s the tunning of your engine that determines how efficient it is at getting power at different RPMs.

          Generally the bigger the engine the higher the power output in its optimum fuel burn range and that’s why large family cars often get better mileage on open roads as the compact cars are operating well out of their range.

          I’ve done plenty of testing taking 50km averages and I’ve always found the slower I go the less fuel I use. This is comparing between 80-90 km/h.

          For my FJ cruiser it tells like I’ve hoisted a sail once I go over 100km/h. Even just going over 90km/h is noticeable.

        5. Patrick, you have taken a hugely simplistic view of the automobile and assumed that air resistance is the main factor in vehicle efficiency which it isn’t.

          The poor ignition of fuel is actually the biggest energy loss in a vehicle, so theoretically a diesel which ignites by compression may well me more efficient at certain higher speeds in the same gear.

        6. You seem to have comprehension or reading problems. The report refers to Melbourne’s rural and outer freeway network. Freeway ie. equivalent to our motorways….and yes, fuel efficiency decreases in going from 100 km/h to 110 km/h. for the same vehicle under the same conditions. If you believe that it increases then you are deluded.

        7. Sailor MFD is right. In a vacuum and with no contact with a surface, and with an engine that runs at 100% efficiency [impossible], you could, in theory, increase speed without needing to disproportionately consume more energy. These factors are currently unavailable on the Auckland motorway system. Although I’m sure the conocopian, techophiliac fantasists out there believe that Google or someone will make this all possible anytime soon.

          So you’re a bit right; air resistance is not the only factor, although it is extremely important. In particular car engine efficiency hits an upper thermodynamic limit of around 37% but in practice the average efficiency of car engines is around 20%.

          It is impossible to shove a lump of metal and its organic contents through the air and in contact with the road with an Internal Combustion Engine more efficiently at 110kph than 100kph. It also can’t be safer to do so either; faster is always more unstable in a dynamic system, reaction times are shorter, stopping distances bigger etc.

          More dangerous, less efficient; dumber. Welcome to planet AA.

        8. Ok, we won’t trust the guy doing engineering and specialising in fluid mechanics, that is fine.
          Air resistance is not the biggest loss in a car, it is fuel combustion efficiency, which may well be markedly better at 110. I very much doubt that it is better by around the 11% that it would need to be to overcome a 21% increase in drag losses.

        9. Also, Aussie Freeways are not equivialant to our motorways, and nor are their single lane rural roads with no grade seperation. Such a claim is laughable. Their freeways would be equivilant to the expressways through the waikato, and the rurals oads would be equivilant to the non expressway sections.

  13. I don’t see why not if its a safe operating speed for the road. Every road has a different safe operating speed, many of which is above the speed limit. There are many roads that are safe above 120km/hr. So this makes sense, but at the same time local roads like Parnell rise should be lowered as with pedestrain movements the safe operating speed is more like 40km/hr rather than 50. Safe operating speeds can be caculated by taking lane widths, curve radius and cross referencing to accident blackspot data etc.

    CMJ safe operating speed is 80km/hr because of sightlines and curve radiuses, although some of the roads are safe at the 100km/hr limit I think NZTA have taken the approach of a general speed limit for the entire area, which makes sense from an enforcement point of view.

    1. What makes you say the CMJ is safe being operated at 80 km/h? Is that based on any geometric data or just quoting the posted speed?

        1. The way people drive here and the way the CMJ feels, I would say that a safe operating speed for it is much more likely to be less than 80km/h not more!

        2. Correct. A number of the elements in the CMJ meet the design criteria for only 60km/h and some are even lower. It’s just like any other road, the posted speed limit is just that, a limit and not the recommended minimum speed.

  14. Just exactly what causes accidents on motorways? Obviously failure to give way isn’t one of them. Is it dodgy lane changes? Lane drifting? Figure out all the causes and see how a change in speed limit would affect those. My hypothesis is that it is the mix of different speeds that has the biggest effect on accidents. The mix causes “turbulence” on the otherwise smooth-flowing motorway.

    My guess is that 110 would make the motorways a lot more dangerous because of people driving at 80km/h – the danger is due to the mix of road speeds rather than the absolute speeds. If you could get those driving at 80 to increase to 90 then 110 would be almost as safe as 100. If not then the mix of speed differences will increase from 20 to 30 which is a 50% jump.

    1. The danger in differing sppeds actually comes froma lack of courtesy and failure to check mirrors in lane changes.

      Western Europe actually has pretty damned safe motorways at way higher speeds because the drivers think about their actions before they take them.

  15. I’ve no objections to this, even as a non- (or very occasional ~ 1x per annum or so) driver. Motorways are the safest roads in common usage anywhere. France’s autoroutes with their 130 km/h limits don’t seem to be dangerous.

  16. “AA motoring affairs general manager Mike Noon said nudging up the speed limit by 10kmh on some roads could reduce congestion and improve productivity by ensuring the quicker movement of freight.”

    Idiot. How is increasing the speed limit going to reduce congestion?
    Do we really want 56 tonne trucks travelling at 110 km/h? That’s nearly twice the kinetic energy of a 44 tonne truck at 90 km/h. I could see that it was only a matter of time before trucking companies starting the push for higher speed limits.

    I am tempted to ask the AA if Mike Noon really made those comments and if the answer is yes to cancel my membership.

    As for increasing the speed limit? No. Higher fuel consumption, More CO2 emitted per km travelled, longer stopping distances, greater energy to dissipate in the event of collisions. I would be prepared to entertain dropping the speed limit on non-divided state highways to 90 or even 80. There are plenty of commentators that focus on accident causation and ignore consequences. Kinetic energy is proportional to the square of the speed and kinetic energy is a reasonable proxy for severity of consequences.

  17. Sydney’s 110km zones all start at about 50-60km from the CBD or on the very outer limits of suburbia. And most of these are 6 lane divided then down to 4 lane divided. (some of the suburban motorways are down to 80-90km) If you apply those to NZ motorways are there any that fit the bill?

    1. The Northern and Southern Motorways in Auckland both continue far past the edge of the built-up area. The Transmission Gully Motorway in Wellington will also be pretty remote. I guess it depends how long you want the 110 zone to need to last for. Minimum of 5km? 10km?

  18. If you did a bit deeper you will see that the speed limit thing is mostly abut reducing speed limits on local roads and on unsafe country roads that are curently posted as 100. There would only be 2 or 3 roads in NZ that would have parts that could qualify for the speed limit upgrade. But the media have jumped on the back of the AA statement and are focusing on the possible increase in speed limit.

    1. “If you did a bit deeper you will see that the speed limit thing is mostly abut reducing speed limits on local roads and on unsafe country roads that are curently posted as 100”

      You are very optimistic. Then why aren’t why discussing that? No, we are discussing some people who want to RAISE speed limits.

      1. Sorry PBY, shot off my mouth too quick without reading your comment fully. But I remain extremely sceptic. My fear is that this discussion will lead to many more roads being sped up than slowed down!

  19. I’ve just checked the fuel consumption of one of my old classic cars (about as aerodynamic as a brick), from a 40 year old Autocar road test. 47.1mpg at 30mph, 34.2mpg at 60mph (100% faster, 27% thirstier), then 30.1mpg at 70mph (17% faster, 16% thirstier).

    Modern cars are much slipperier, so the increase in fuel consumption isn’t so marked.

    Changing the open road speed limit hasn’t had much affect on fatality rates in the past, the drop from 100kmh to 80kmh in the ’70s

    1. Modern cars have a better Cd but the increase in drag is still proportional to the square of the speed.

      Here’s a very relevant quote from an NZTA document:

      “One of the most recent evaluations of changes in
      speed limits examined the change from 100 to 110 kph on
      Melbourne’s rural and outer freeway network in 1987 and
      the change back to 100 kph in 1989. Sliogeris (1992) found
      that, compared to a control group of all other roads in Victoria
      that remained at 100 kph between 1987 and 1989, the injury
      crash rate per kilometre travelled increased by 24.6% following
      the change from 100 to 110 kph, and decreased by 19.3%
      following the change back to 100 kph.
      There is a consistent finding from the studies referred
      to above that shows that increasing the speed limit increases
      crash, injury, and fatality rates and that decreasing the speed
      limit can reduce these rates.”

      1. Slam dunk! All those people who advocate ths are happy to increase the ‘injury crash rate’ by a quarter. Insane.

        And reduce road use efficiency, and fuel efficiency. The AA are certifiable nut jobs we know, but most commenters here too.


        1. Don’t see how you can possibly argue that this reduces efficiency?
          By having a road that occasionally runs faster than present you can only increase efficiency. Also that report is on rural roads not the most heavily policed roads which are the safest sections within new zealand.

        2. Yep, efficiency of a road can be defined in many ways.
          Cars per hour, passengers per hour, average vehicle speed, litres pre km, ltres per person km. This can only decrease the last 2, and can increase the first 3, which I would say are the more obvious of the road efficiencies.

        3. Which is fine on the weekend but then productivity isn’t as important on the weekend. Most weekdays, the traffic is too busy for the whole day for 115 km/h to become the new norm.

        4. a) You obviously don’t ust the Northern Motorway much,
          b) It won’t become the new norm if there is too much congestion.

        5. a) don’t know what this relates to but I use the road on a reasonably frequent basis and at quite differing times and have been using said road since it was opened (I also remember having to stop for the lights at the top of Sunset Rd – I digress).
          b) I believe there is already too much congestion to safely raise the limit from 100 km/h especially considering the time saving – roughly 1 minute from Oteha Valley Rd to the Puhoi tunnels.

  20. I disagree with the idea of having the Hutt Expressway at 110kph. Especially when there are cyclists and traffic lights on that road.

  21. No.

    Firstly, it will increase rather than decrease congestion. As we saw here recently, the faster a vehicle is travelling, the greater distance needed between it and another vehicle for safety; it essentially models as a non-linear function. Higher speeds mean less people passing a point over a time period, not more. Once people have less than that space, they slow, and as humans we slow more than necessary. Scrubbing off that speed slows down the person behind, passing like a wave.

    These slowings cause nose-to tail accidents, as people enter with too much speed or not enough reaction time to slow or stop properly. People slow at all speeds. Add 10km/h to vehicle speeds and the results will be worse. Similarly, the crashes will me much worse, and we’ll see the police and emergency services shutting down the motorway for hours at a time, impacting on that motorway and the entire system. Not to mention the massive human cost of even a single extra fatality. You can be sure that increasing speeds will increase both the likelihood and severity of such accidents.

    You’ll also get those who now think it’s okay to do 110, moving up to 120. That I guarantee. As Paul in Sydney says, in Australia the 110km/h roads aren’t urban ones. They’re the country’s flagship highway system between cities of 3 – 4 million, with the quality equivalent to that which we have between the bottom of the Bombays to Hamilton. That’s about the only NZ road I can think of in that condition, and we’ve only just upgraded that section after losing hundreds of lives there over the last couple decades. Every other Australian road is 100 or 90. (Except in the NT, where limits across what is essentially vast flat desert are 130, down from unlimited during the 1990s).

    As I’ve said before recently, if you want to reduce congestion, you lower speed limits with variable speed limit signs, which can go all the way from 40 to 100, depending on the optimal flow of traffic at that time.

    There are lots of contenders for the most idiotic things said by the AA, and this is one of them.

  22. How about a similar rule to the one they have in France, where all speed limits are reduced by 20kph when it’s raining. ie 110 becomes 90, 50 becomes 30 etc. I’ve lost count of the times I’ve been driving on motorways at 85-90 in the wet and had a truck barrelling past me at 110 throwing up spray in all directions. (Hasn’t happened for a few months admittedly).

    There are a number of more sensible measures to concentrate on – as mentioned above trucks limit of 90 to be enforced, tailgating, keep left unless passing, no undertaking, charge those who try and overtake 50m before the end of a passing lane (and therefore HAVE to cross the double yellows to complete the manoeuvre-I’ve recently been caught up in someone elses accident because of this and get rid of stupid passing lanes at the bottom of hills. Trucks come barrelling down hills at 110 and most kiwi drivers with their mentality of “must get in front” then have to do 130 to get past the truck before the next single lane section.

    I drive a lot (have to as there is no public transport where I live) and every day I see stupid drivers doing stupid things. I could write a book. What’s even more worrying is that a huge percentage of the cars are unregistered (and therefore probably unwarranted, uninsured and drivers unlicensed). Totally unscientific I know, but the other day I walked around the Albany Megacentre car park and 10% of all cars parks had expired licenses and/or warrants. Effective policing and sensible severe penalties are what is needed to get these irresponsible idiots off the roads and make them much safer.

    1. Poxy WordPress Comments plug-in- that was a +1 to Bryce’s compromise of 110 allowed on some roads in exchange for 30 on suburban roads.

  23. Hardly a game changer a +10kph increase even if you could drive long distances at that speed versus 100kph.
    Now high speed rail, 320kph, there’s a game changer.

    Pity we ain’t got no money …

    1. MrV,
      On that point re: +10kph difference over even a long trip I agree with you its a best 10% better, at best.

      The TV3 news team “comedy duo” did a test on exactly that last year on the difference between driving at 100k and 110k on a real Auckland Motorway and found no significant difference in actual time savings overall for even moderate distances like 5-10k.

      Agree, High Speed rail, is a game changer for long distance travel.
      One day when the planet ad this country kicks its expensive oil habbit then such plans will come to pass I expect,

    2. Long stretches of SH2 to the Coromandel changed to 90 km/h limit some time ago, and the journey down there for the summer holiday at the beach was noticeably more relaxed and felt a hell of a sight safer as a result. It also didn’t take any longer than it used to. Of course, not a motorway, but it does reinforce MrV’s point about +/- 10k not making much meaningful difference to overall travel times.

      1. David I really like that new 90kph SH2; I drove it last week and think it shows that the AA is exactly wrong in the direction we should be changing our speed limits. I look forward to see the crash data form this stretch too. It will be reducing tragedy.

  24. Most parts of recent new motorways built, such as Hobsonville, are designed for 160km/h, so 110km/h is well within the safety margin.

    In Victoria, 110 zones are common, including on some ordinary two lane roads.

    1. Ah yes, the safety margin. I have just returned from a (mostly) pleasant outing to Clevedon. Part of the journey was on the Southern motorway. My daughter pointed out that the driver of a large Bonney’s container truck was busy texting as we passed his vehicle. It doesn’t matter how “safe” the road is when we have tosspots such as this operating vehicles on it.

  25. Conversation is about fuel efficiency which higher speed limits are likely to reduce.

    As for network efficiency, this is complicated. There are good reasons why many networks around the world use variable speed limits and reduce them in the peak times – because flow is more efficient (ie more vehicles per second) at lower, not higher speeds. This is because higher speeds necessitate larger distances between vehicles and reduce the traffic density that can be safely maintained. It’s complicated:

  26. Increasing the speed limit for cars and other light vehicles from 100 kph to 110 kph would make it safer to overtake 20 metre long trucks travelling at 90 kph which at the moment on a two lane highway is legaly impossible

    1. Some US states, and apparently Spain, allow you to exceed the speed limit by a certain amount only when overtaking, which would give you that benefit without raising the speed limit everywhere.

  27. Exactly Bryce P,

    A 44 tonne 20 metre long truck and trailer unit or B train travelling at 90 kph has a velocity of 25 metres per second.

    How can any anyone safely overtake a vehicle that long travelling that fast ! talk a about speed kills !

    Only 6 % of the total distance travelled on NZ roads is travelled by trucks, yet deaths from crashes involving trucks make up 15% of the total road toll.

    In most European counties there is a 20kph safety speed difference between heavy trucks and other vehicles. You are correct, the speed limit for trucks should 80kph, and truckers would benifit by reducing their fuel bills by 20%

  28. I’m from Germany. I drove in NZ for a year (about 25000km) and I find your roads and motorways really good. Even most state highways I experienced would be safe for 110 in my opinion. I mean to be honest, people drive faster anyway, right? The normal highways in our country are limited to speed 100 too, but most NZ state highways are probably a little better and safer.

    I read the argument that the European motorways, or our Autobahns, allow much higher limits. This is true, however I think when I recall the situation on NZ motorways, they are not as wide as Autobahns in Germany (about 3-4 meters per lane) thus not as safe for speeding.

    There are areas without speed limit hre but mostly in the more rural parts and there it’s perfectly safe (plus a lot of fun). Of course it’s different for areas with high traffic, I’d say about 40% of the Autobahn network is limited to 130 or lower. Berlin is propably similiar to Auckland in that regard and the city motorway is limited to a 100 or lower there too.

    There are a few rules that make our Autobahns safe and which should be taken in consideration, I think.

    – no overtaking to the right (left in NZ)
    – limit of 80km/h in all tunnels
    – limit of 80km/h for all trucks, buses 100
    – keep right (left NZ) if you are slow or unless passing
    – minimum speed of 60km/s for cars
    – limited speed near bigger junctions or ramps
    – areas with limit speed during wet conditions
    – minimum car distance of 50m or at least 1/2 of the clock value (e.g. 100meters at 200kmh)

    oh, and by the way, for the environment lovers: I have a 98 Mitsubishi Carisma 1.8l GDI and use about 6-7l/100km on speed 160 (4000 rpm) on fairly flat terrain ;-). It only goes over 10liters over 200. Considering newer engines are much cleaner, this can’t be a serious argument against a higher speed limit. Then again a truck limit of 80 could make a difference.

    All in all I think 120 would be alright for the modern motorways IF they are wide enough and go straight, and with the option to dynamicly reduce the limit at times with high demand.

    anyway stay safe, Kiwis 🙂 Hope to visit your great country again one day.

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