Accident severity (source:

This is one of the more common traffic diagrams depicting how vehicle speed leads to increase accident severity. I have seen versions of this in different languages and the two common measurement systems. I would expect this information to be imparted to transport professionals on day one or two of school. Upon arriving to New Zealand I was shocked to learn that streets have the default speed limit of 50 kph which includes most residential areas in Auckland. There is some progress to address the issue around school zones but raises the question of why aren’t other places designed and controlled to consider people’s safety and accessibility.

Below  is an embarrassing effort to slow traffic to 40 around a school zone in Auckland. Do kids not come and go to school at different times? It also fails to consider that other, non-students, would be using the school as a community facility who might also benefit from lower speeds. Check out the time range as well. I’m sure someone cleverly determined that it takes the students 10 minutes less time to leave school than to arrive.

If you can read this sign, you’re not going 50

This one is a beaut as well. After heroic efforts by Walk Auckland to successfully lower speed limits on Ponsonby Road to 40kph, this narrow residential side street remains posted at 50kph. Even the most psychotic hoon wouldn’t take this stretch at 50, so why in this rare case of a properly scaled, people-friendly street would a sign be posted to suggest higher speeds? This is street design on v. 1970 auto-pilot mode.

Narrow residential ‘queuing’ style street posted at 50k

Children, of course, are particularly vulnerable road users. A 2011 study at Royal Holloway, University of London revealed that school-aged children do not have the ‘perceptual acuity’ to properly distinguish vehicle distances when vehicles are traveling fast than 20mph (32kph). Professor John Wann, from the Department of Psychology at Royal Holloway, who led the research, says:

“This is not a matter of children not paying attention, but a problem related to low-level visual detection mechanisms, so even when children are paying very close attention they may fail to detect a fast approaching vehicle.”

I was reminded of this research when walking my kids to school last week.  I saw these poor kids waiting on the street corner waiting for a gap in the stream of cars winding through our street. I had to cross the street myself to help them get across (Boy Scout points!). For a variety reasons the streets in our residential neighbourhood are unnecessarily dangerous. There are some tacked on bits and bobs that are an attempt to improve safety and comfort, but they are mostly half-assed.

Looking both ways

The inability of people to simply get around without a car also contributes to further health problems. Recently the associate medical director of the British Heart Foundation called on the local Governments to adopt 20mph (32kph) limits on streets in order to provide safer conditions and to encourage more walking and physical activity.

‘Parents want to see safer streets – the Government must change the standard speed limit to 20mph on the streets where we live, work and play”

And finally, here is a quote from an excerpt of what looks to be an excellent new book called Walkable City describing how cities are moving to much slower residential streets:

There are currently more than 87 “Twenty’s Plenty” campaigns in the UK, and about 25 British jurisdictions, with a combined population of over six million, have committed to a 20 mph speed limit in residential areas. In June, 2011, the European Union Transport Committee recommended such a rule for the entire continent. It is easy to imagine 20 mph becoming a standard throughout Europe in the near future.

I know Hamilton City is working on changing their speed limit regime. Auckland needs to play catch up. As a starting point all residential streets should have blanket speed limit of 40kph. Justification for higher speeds based on network function could then be made on a case to case basis.

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  1. Amen! I live in Pukekohe in a street that is a ‘through’ street (Victoria Street), but not very wide – when there are cars parked on both sides, two cars have to slow ‘way down in order to pass one another. It is ridiculous that the speed limit is 50 – which means, practically speaking, 55 or so for those who are just worried about not getting a ticket. I try always to drive about 40 – and cars behind me tailgate, clearly annoyed at my slow driving. Because it is a through street, you get people hooning up through it, to (we hope!) jam on the brakes at the stop sign at Helvetia Road.

    I have always thought the default residential limit should be 40.


  2. Forget 40, follow the Dutch and go to 30 km/h on anything that is not deemed a collector road. Obviously some road engineering will be needed but making the streets safe enough for children to walk to school is well worth it in my mind.

    1. Oh, and the reason for 30 is psychological. People may still do high 30s but if you start at 40 they are more likely to be going closer to 50 when the street appears empty.

  3. Makes total sense. I recently presented a proposal to the Henderson-Massey Local Board for a low speed zone in the part of my Te Atatu electorate bounded by Lincoln Rd, Universal Dr and Swanson Rd. It has six schools in close proximity, and suffers loads of rat running and boy racer speeding. The schools can’t get the kids to bike or walk to school because parents feel the traffic is too dangerous. Lowering speeds to 30km through chicanes, planting and narrowing the streets as was done in the successful Pt England project and for that matter parts of Ponsonby and Herne Bay in the 1970s, would make these neighbhourhoods a lot safer and more liveable.

    1. Will the Labour caucus consider a policy of abolishing the 50km/h speed limit entirely, replacing it with 30km/h except where the local authority imposes a 40km/h or 60km/h limit because the road design and intent supports the higher limit?

      The article about Hamilton’s proposal made it pretty clear that 50km/h is not grounded in anything, and the graph above makes it clear that it’s about the worst possible choice between “efficiency” and danger for residential areas.

    2. I once saw a (I believe Waitakere City Council) document about applying to Council for a speed limit on your local road to be lowered. Basically I think you had to get the signatures of 75% of all people in your street to agree with the idea before they would look at it. So taking this more seriously would be welcome.

      > The article about Hamilton’s proposal made it pretty clear that 50km/h is not grounded in anything, and the graph above makes it clear that it’s about the worst possible choice between “efficiency” and danger for residential areas.

      The article to me also makes it clear that Hamilton Council is also looking at speeding some roads UP. What about people walking / cycling / living on those new 60-80 km/h arterials? So don’t take this all as some nice touchy feely initiative.

      1. Hamilton already has a bunch of 60km/h roads, though, and in my experience they’ve got marked, wide shoulders to facilitate cycling and also have footpaths. They’re definitely through roads, often with a high mix of commercial. I haven’t driven on any of them (and I have family in Hamilton so I spend a bit of time there) and wondered why the limit was so high. I would suggest that you experience what Hamilton’s current road environment is like before getting all negative about what’s proposed.
        Hamilton’s not Auckland. There are very few roads that would become 60km/h zones that aren’t already, and unlike Auckland most of them have feasible alternatives on parallel blocks that will be 40km/h zones. There’s no harbour to bugger up road layouts, and most of the bridges across the river will be 40km/h because that’ll be the limit on both sides; the one that’s on an 80km/h road has a well-separated path on the approaches and barrier-separated footpaths. You can’t just transpose your Auckland prejudices to a city that’s got an entirely different geography.

        1. > I would suggest that you experience what Hamilton’s current road environment is like before getting all negative about what’s proposed.

          > You can’t just transpose your Auckland prejudices to a city that’s got an entirely different geography.

          You are being pretty touchy when all I said was “don’t treat this as an effort that is all about lowering speed”. When someone wants to speed up a road, I am not allowed to ask whether that is positive? I am actually not opposed to the initiative as such. But yeah, I have seen WAY TOO MANY initiatives proposed under the guise of “improving” our transport environment that were all about car-centricness, so excuse me if it peeves you that I have gotten a bit sceptical here in my Auckland prejudices.

      2. Great intel, thanks for that. Six houses and a playcentre on our street out west, a short link which is used as a cut-through. I might just try that application route out for size and see what AT does…

  4. Here in Basel, Switzerland, all side streets are 30 km zones. I got a nice 60 Swiss Franc (NZ $80) speeding ticket for doing 33 km’s last year by a hidden camera. Fair enough and now I watch my speed in the 30 zones.

    Grays Ave in Middlemore is a classic case of a suburban road that needs to be 40 kms with speed reducing measures. At present this road, with a high school on it, is often a boy racers joy road.

    So I support a blanket 40 km speed limit in Auckland, 30 km for side roads and higher only by justification.

  5. “Lower speed limits dramatically reduce the risk of death”…or more correctly lower speeds do. They have to be enforced. The current speed limit for passing a school bus dropping off or picking up passengers seems (in my experience) to be very poorly observed and enforced. I like the US practice of flashing red lights on the bus and a legal requirement for other road traffic to stop.

  6. Hamilton are increasing the speed limit on most main roads to 60km, something which Auckland has in a few areas already. They are also doing away with 70km zones (they are either going to 60 or 80) and most country roads are going to 80km while main rural roads are staying at 100km.

    I also want to point out that by far the majority of students arrive and leave during the school zone times AND schools have the ability to turn on the variable speed signs when required, say for a school trip or if school closes early.

    1. What you didn’t say is that Hamilton will be doing away with 50 zones entirely. Residential streets will be going down to 40.

    2. I think commercial streets in the city will also be going down to 40km/h. Pretty much the new speed limits will be based on the purpose and use of the street rather than just as to it being inside or outside the city limits.

    1. Plus 60 on appropriate arterials…. But exactly right Rob.

      And important post Kent. More Californians I say…. That chart up top; the huge difference in human misery between 50 and 30 is surely the end of the discussion…?

      1. Not really, because I have seen (even on this blog) lots of people make the “guns don’t kill people, people kill people” type argument – i.e. it’s not the speed limit that should be changed, it’s people who don’t drive to the conditions blah blah revenue gathering blah blah more education blah …

        Surprised that you favour (even in a half throwaway sentence) 60 km/h speed limits on arterial, Patrick. With the current government in NZ, any talk of changing speed limits will leave us with some advisory language about how speed limits in residential zones could be “looked at” (or “studied further”, just like reduced alcohol limits) while 60 km/h arterials and 150 km/h motorways are signed into law by next Wednesday…

        1. The whole point of arteries is to move stuff. They’re heavier-duty, wider, and stuff moves at greater velocity. That’s pretty much the definition of an artery. An arterial that’s got the same 40km/h speed limit as residential side roads isn’t actually much of an artery. We already have higher-speed arterials in most cities in this country. Jackson St in Petone, Pakuranga Rd, I’m sure Christchurch has something, Hamilton’s got an 80km/h nearly-motorway pushed through a small segment of its riverside, Tauranga’s got a few, etc etc.

          Your comment about 150km/h motorways shows where your total bias against any increased speed limits anywhere really lies. Puts you in the same camp as Patrick’s automatic reaction to any project that might add another lane of motorway, anywhere.

          1. Hi Matt. The problem with Pakuranga Road (the only on the list that I am really familiar with) is that the limit is 60 km/h and yes it is wide but in the design sense, as far as safety of all users, it does not meet basic European engineering standards. It has been designed solely to move cars. In my mind, it is need of a drastic redesign in order to be a real 60 km/h arterial. Another issue is that the default speed of 99% of traffic on this piece of road is actually near 70 km/h (recorded using GPS).

          2. Arteries will still move stuff with a slower speed limit. They just won’t move it as fast. And you’re kind of proving ingolfson’s point about government – plenty of arterials (not including Jackson St, by the way) do have higher speed limits, but residential streets almost all do not have lower limits.

          3. After looking at a 70km/h road in Assen (the Dutch don’t have 60km/h roads I believe) using the wonder of street view, I now think that Pakuranga Road either needs to be a 50 km/h road, as is, or a 70km/h arterial by reducing general traffic lanes to 4 and building a 30 km/h parallel road on each side thus encompassing as safe route for local traffic, cyclists and pedestrians. The ‘in between’ that we have now, with driveways entering directly on and off a 60 km/h road is unsafe for pedestrians and cyclists alike (there was a fatality there a couple of years ago?) and is well behind any current level of road safety that is being practised in other parts of the world.

          4. And if you were going to redesign Pakuranga Road, I would include a central corridor for 2 x tracks of LRT (Bombardier ART 200?) to Highland Park and then route it, somehow, to Botany and on to Manukau. Stations would in trenches and be accessed under the road, it would run under intersections but most of the route would be above ground (off topic slightly I know :-))

          5. Matt, the fact is that it’s all fine to say arterials are about moving stuff. That doesn’t absolve planners of the downsides of speeding them up. Designating a road an arterial does not remove the people who live on it, and who have kids, and chairs on their porches, and want to walk to the neighbours.

            And I will say it again – I have seen too many initiatives from this government to trust them with much of anything in terms of transport policy. You seem to be awfully protective of the Hamilton policy, probably because you have already come to the conclusion that I hate it, and so all I say must automatically be wrong. I am talking of the fact that if our current national government starts talking about speed limits, it won’t be having liveable streets at the forefront of their minds. Do allow me that suspicion or not, I don’t care.

  7. After the overly-precise times, the next best thing about the sign is “SCHOOL DAYS” – how is anyone who isn’t a parent of a school-age child supposed to know which days are school days? Are they even the same at every school?

    The confusion about driving in Auckland is dangerous too – so many of our main roads are four lanes, but no-one uses the left lane because it’s always changing between bus lane, clearway, parking, or a sudden forced left turn. Everyone’s going too fast and then someone realises they actually should be in the other lane, so they swerve without indicating.

    Lowering speed limits to 30 will help on side streets, but if we’re going to keep a high limit on the arterials, we need to do some work there too. A good start would be putting the roads on a diet back to either one lane each way + parking, or one traffic lane plus a continuous bus lane, and then keep that the same 24 hours a day.

    1. Those “8:05am to…” times are the most ridiculous thing ever. Even with an electronic sign clearly specifying they are in force, they are just a band-aid, as Kent has pointed out.

    2. If, for some reason, it is unfeasible to reduce the speed past a schools entrance then we should be seriously looking at moving the entrance to the school. Yes there may be houses in the way but sooner or later a house that can be removed to make a new entrance will come up for sale. $600k (or even more) for a house is cheap compared to rebuilding a road.

      1. If it’s ok to demolish / remove over 100 houses for a motorway then surely the removal or redevelopment of the occasional site to ensure the safety of children is also ok?

        1. Those printed signs with times are really stupid. At the very least they should be electronic signs that light up and turn off. But really it should just be a 30 or 40 km/h blanket limit.

  8. Well, you’ll get no argument from me about the general premise here; there are so many things in favour of lower speeds. Of course “technically” we can already implement them; the problem is systemic: councils are not really encouraged by the existing policies or guidelines to do so, so you’re relying on the ad hoc goodwill of a few good initiatives around the country (e.g. Hamilton and Wellington). Bad luck if you live elsewhere…

    One note of caution about the original speed-vs-fatality graph at the top of the article; it’s used everywhere, but, um, it’s wrong. Actually your survival chances are (a lot) better than that; the original studies were methodologically flawed and modern vehicles and medical intervention also improve your chances. But the take-away message is that the risk of pedestrian fatality if struck at 50 km/h is still twice that at 40 km/h and five times that at 30 km/h.

    With my students, I’m slowly working through various bits of research to try to fill in some of the technical and policy gaps in speed management in NZ; NZTA are also working on this area at the moment (albeit a little slowly for my liking). If you want some more info about the state of play in New Zealand, I suggest looking at my paper on Implementing Lower Speeds in New Zealand –

    1. From Glen’s [excellent] paper above; looks like a plan to me:

      “In Europe, another increasingly common approach to road safety is to match speed limits and road environments, based on the potential damage and survivability of a situation (Wramborg 2005). For example:

      • where pedestrians and cyclists are present (e.g. residential areas): 30 km/h
      • where side-on crashes could occur (e.g. at-grade intersections): 50 km/h
      • where head-on crashes could occur (e.g. overtaking, roadside poles): 70 km/h
      • where traffic is fully protected from the above dangers (barriers, interchanges): 90 km/h+

      These so-called “forgiving roads” ensure that, whether drivers erred through bad choice or bad luck, they (and other road users) will still have a good chance of surviving the result of that error.”

  9. Developers have been designing roads for lower speeds for years and drivers have by law be told to drive at 50 kph on them. These speed changes should be changed at the same speed as the right-turn rule was changed.

    Aug 2010 Hamilton City Development Manual. part 3: ROAD WORKS. page 2
    Design for cul de sac 20 kph with 400 vpd. Minor Access 30 kph with 800 vpd

    1. Remember the speed limit was never a target or a minimum requirement, it was a limit. I often find myself wondering sometimes when I am driving through the 80km/h sections of the motorway with my cruise control set to 80km/h if its actually safe to be going at that speed, in a way it almost feels like I’m walking on the motorway as everyone else it going so fast.

    2. suburbs of Hamilton built about 5 years ago are dreadful and have huge wide roads, not even paint marking to delineate parking spaces.
      However those built in last year or 2 are much better and have traffic calming devices, also much better legibility such as simple sculpture at roundabouts. Makes it much easier to find your way around if there are some distinctive elements.

  10. Something which few road designers seem to know about is the 30/50/70 rule. Pretty much it says that if you want cars and pedestrians or cyclists near each other you need to be looking for a 30km/h speed limit. At 50km/h they should be separated by a wide grass berm of something, on-road cycle lanes and zebra crossing or crossing at traffic signals. At 70km/h they should be physically separated by a barrier or something and have crossing in the form of bridges or underpasses and all cyclist should be on off-road paths.

    Sadly this is something that is only really told at safety workshops and so most designers, engineers and even the RCA’s don’t know much about it.

    1. Important point there too. If it were 30k there is no need to cycling paths etc as they can just flow with the traffic. I think speed is more important to encouraging cycling than cycling lanes everywhere (I am a cyclist too). I can’t get everywhere turning left 🙁

        1. I’d say both, there are obvious routes were it’s good to have a cycle path and it wouldn’t be practicable to go for a 30km/h speed limit, such as the Northwestern Motorway. But once you get into busy areas such as Broadway in Newmarket a 30km/h speed limit would be ideal, half the time you can go much faster than that anyway.

        2. It all depends on what challenges you face in terms of geography and street layout / width. The Dutch have both in some places but not others. If you have an area where you have the room to build a cycle path then do so by all means but if you are hamstrung by layout then a 30 km/h road is ok but not perfect (much better than we have now). In fact, if we were to take the Dutch cycle and road design manuals, and apply them to NZ, I don’t think we could go far wrong. (From what I have read, the biggest mistake most cities make is just taking parts of the designs and then they wonder why the results are not what was expected.) After all, they have organisations like SWOV who study road safety as their mission. Why not learn from a country that has been doing what we are talking about for the past 30 years rather then re-inventing the wheel and assuming what we could do may be right or wrong?

      1. It does depend on context, but I tend towards less so for the cycle lanes. I hate the way we segregate traffic and strongly dislike wide roads with many lanes (whatever type they are). I think slow speeds on Dominion Rd rather than a cycleway is more important.

        1. Slowing Dominion Road down is fine but what we should be aiming for is 8 to 80. That is infrastructure that is suitable not only for commuter cyclists but for 8 year olds through to 80 year olds and with the traffic volumes on Dominion Road, I would say that is not a good solution.

  11. I can hear the screams from the AA and RTF already about how any change to lower the limits for roads is not about safety but just another anti car statement. I can also imagine the kind of comments such a move would generate from certain sections of society about how they are great drivers and should be allowed to go faster, not slower.

    1. Sorry -thick thumb!
      Good god man! Have you thought about Joyce’s blood pressure if he gets wind of this?
      This would entail people taking longer to get somewhere? And not just people but drivers!

        1. haha. I witness this every day on my bike- the turtle and hare fable. In fact, I increasingly see cyclists in lycra thinking they are getting somewhere faster. Slow and steady wins the race, dude. Ask the @wheeledped

        2. From the experiences I have found in the CBD, if the light turns green and you floor it you can make it through the next few sets, if you go any slower you will have to stop at the very next light,

    1. Nice work that they’re getting rid of minimum car parking requirements but a bit odd to replace them with minimum bicycle parking requirements.

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