Removing centrelines can be done easily when carriageways are resurfaced, with an immediate saving in capital and ongoing maintenance costs. – Manual for Streets 2

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Why kids don’t walk to school (Golflands, Auckland)

Interesting research was recently published on how removing (or not reinstating) centre lines reduces vehicle speeds. This is a similar conclusion to research conducted in the States over 10 years ago, but perhaps with a different imprimatur and accent this study may be more useful in the New Zealand setting.

The study by Transport for London measured three residential streets: Seven Sisters Road, Harringey (Streetview), Wickham Road, Croydon (Streetview), and Brighton Road, Coulsdon (Streetview). The streets all have a medium density residential context and appear to have a modest role in the transport network  including some bus and bike facilities.  I’m guessing that there are over 7,000 cars a day on these streets.

As an aside, it’s interesting to see how different the streets and network structure is here compared to Auckland. It’s hard to think of a direct local comparison for these streets. It is much easier to compare our streets to North American cities like Calgary, Seattle, and San Diego.

So back to the study. After removing the centre lines (in cases striped medians, yuck) the following results were measured.

after

Wow. So roughly speaking by removing the centrelines the vehicle speeds have dropped about 5 kph. Critically, this vehicle speed range is where stopping distances are significantly longer and accident severity becomes increasingly life threatening so even modest speed reduction is significant.

The psychology of the results is discussed briefly, but somewhat inconclusively- “getting into the minds of drivers is not easy”.

A theory is that centre lines and hatching can provide a psychological sense of confidence to drivers that no vehicles will encroach on ‘their’ side of the road. There can also be a tendency for some drivers to position their vehicles close to a white line regardless of the traffic conditions, believing it is their ‘right’ to be in this position. Centre line removal introduces an element of uncertainty which is reflected in lower speeds.

The study doesn’t stop there. Using a control site on a different section of Wickham Road they compared the results to a status quo resurfacing project. The resurfacing project alone increased vehicle speeds by 7.2 kph. This is due to the fact that drivers have more confidence since road surface irregularities are removed and bright new lanes are added. The researchers concluded that for resurfacing projects the speed reduction value should be adjusted for that difference, resulting in an absolute change listed below.

adjusted

Removing centrelines along residential streets in particular during resurfacing projects slows vehicles more than 10kph.  This is something that should be investigated further in New Zealand.

Meanwhile, below is a residential street in Mt Eden/Balmoral.  Like the first photo above this one runs in front of a school. I don’t know what the double stripes mean (I got my drivers license from a Wheetbix box), but it seems to be suggesting that cars can overtake?

This situation, like slip lanes, flush medians, splitter islands, and pedestrian refuges is a good example of how road design has creeped into the urban context of street design. How long would it take to identify the residential streets across the city that don’t need stripes? How much money would be saved from stopping the endless re-striping of these streets?

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Why kids don’t walk to school (Mt Eden, Auckland)

As I’ve written before, the default speed limit of 50kph on New Zealand’s streets is politely, inconsistent with international best practice, and more accurately crazy. One of the standard traffic engineering excuses for not lowering speed limits is that the design of the street influences the vehicle speed, not speed limits, so it’s not worth bothering. I get that to a point. The presence of car parking, lane widths, mature street trees, intersection density and other factors combined have a much bigger influence on travel speed than sign posts. But is there any other profession that would sit back and not actively address the serious safety issues of their own domain?

In the absence of a road rule change, narrowing lanes, adding mature trees, and tightening intersections, I am suggesting that this “do nothing” solution of removing centrelines may be something that can be done to make our neighbourhoods safer and allow more people to get around on foot and bicycle. In a subsequent post I will describe another simple proven technique to lower speeds.

Bringing the default speed of neighbourhood and urban streets to 30kph, both by design and by law, should be a high priority for the world’s most livable city.

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65 comments

  1. “Bringing the default speed of neighbourhood and urban streets to 30kph, both by design and by law, should be a high priority for the world’s most livable city.”
    100% agree.
    Anecdotally, the council has added side stripes to Aran Rd in Browns Bay. It’s a curly narrow road with a lot of on street parking that people used to speed down (quite steep in sections). I guess the idea was to narrow the street to reduce speeds. Would prefer to see your approach trialled as it should have the same effect for zero effort!

  2. Kent, What speed are you recommending that Auckland Transport should REDUCE the road speed to here in Auckland by having no center Line? Also would you expect tht speed to be Universal across all of Auckland as we know it.

  3. I don’t know what the double stripes mean (I got my drivers license from a Wheetbix box), but it seems to be suggesting that cars can overtake?

    You follow the instructions on your side. In the case of the photo, vehicles on the left (away from the camera) can overtake & pass until the spped bump, vehicles on the right, can’t overtake. The two (normally three) broken sections of yellow means that there is a solid section of yellow no passing ahead

      1. If you’re overtaking a slow moving cyclist or inner city horse, yes. Wait for space, pull out and overtake. I wish more drivers would do that properly.

        1. As was pointed out here the other day it seems the law actually allows you to cross a yellow line to pass a cyclist, but this doesn’t seem to apply to flush medians.

        2. @conan – The road code is a document prepared by the NZTA to give some idea of what is expected when driving and is the basis for getting a drivers license from them. However, if it is the laws relating to the roads you are interested in, this is where you go: http://www.legislation.govt.nz/regulation/public/2004/0427/latest/DLM302188.html

          The relevant clause is this one: http://www.legislation.govt.nz/regulation/public/2004/0427/latest/DLM303051.html

          “The driver must not pass or attempt to pass a motor vehicle or an animal-drawn vehicle moving in the same direction within the length of roadway on which the no-passing line is marked until the driver reaches the further end of the no-passing line, unless throughout the passing movement the driver keeps the vehicle wholly to the left of the no-passing line.”

          As a cyclist is neither a motor vehicle nor an animal-drawn vehicle, the law preventing you from crossing a no-passing line does not apply. This is also the case for stopped vehicles, pedestrians, forklifts coming towards you etc.

        3. You are right, however I suspect that the following clauses would be accepted as the reason for conviction by any court faced which such a case:

          2.6General requirements about passing other vehicles
          (1)A driver must not pass or attempt to pass another vehicle moving in the same direction unless—
          (a)the movement can be made with safety; and
          (b)the movement is made with due consideration for other users of the road; and

    1. Try it, Mike. At least try 30 +10, on side streets. Or where there are children on the footpaths. Do it for three months, so it becomes a habit. Easy. I guarantee you will never race around at 50 +10 on those streets again.

  4. Well I for one am glad Kent Lundberg is not in charge of our traffic system because he would cost the Auckland economy billions and drive people to insanity.

    Isn’t the whole point of building cycling and pedestrian infrastructure to separate them from the road so traffic can flow smoothly at current speed limits whilst ensuring other mode users are safe? If so then why would you attack vehicle speeds? We should be aiming for an efficient multi-modal transport network, not by destroying the viability of vehicle travel but by building infrastructure that provides citizens with choice.

    I’d also like to know some additional details about the study
    – Did the study measure the crash rate and if so was there a difference in crash rate before and after?
    – Did the study occur over a short or extended period i.e. Was the change in speed a long term adjustment or was it a short term adjustment that then corrected itself in the long term once drivers became familiar with the conditions?
    – What was the environmental impact of increasing trip length?
    – What was the economic impact of increasing trip length?
    – Did the study look at observation of other road rules and was there any impact from removing the center line?
    – Did removing the center line alter vehicle numbers using the road?

    1. Do you have any empirical evidence for your claim that a minor reduction in speed on residential streets would cost billions?

      Kent linked to several studies that support his claims about the outcomes from removing centrelines. If you have questions about those studies, I suggest that you read them yourself.

    2. How will it cost the economy billions?

      Driving slower uses less fuel, crashing slower costs fewer lives. Slower is always better in built areas, as no time is lost getting between lights or stops signs, you’re gonna be waiting at the next intersection anyway no need to rush to it.

      Billions is a big number, if you’re going to use it it might be best to show how you come to choose it.

      I might add NYC has just gone to 25mph, and the UK has a big ’20 is plenty’ [also mph] campaign and has it enforced in some areas. Are these crazy people happy about throwing away billions [or would it be trillions, seen as they’re bigger?]?

      1. Time is money Patrick and slowing everyone down will result in longer travel times. If slower is better why don’t we reduce the speed limit to 5kmph?

        In another thread earlier this week John the economist replied to one of my points stating that he was an economist and that he wouldn’t be making assertions if he didn’t feel they were right. Given that standard went unchallenged I’m somewhat surprised at your assertion that I prove my evidence. Obviously the amount who depend on the detail, how widespread these limits would be, where they would be and crucially if drivers would adhere to the limits.

        You seem to understand that there is an economic benefit to reduced travel times via the CRL why is it so hard to understand the same concept in a roading context?

        Finally, if I was a “nutter with too much time on my hands” (Patrick’s quote not mine) I would review all those studies. I feel like we are only getting a small part of the story here from the writer and a rather incomplete picture of the effects.

        1. “If slower is better why don’t we reduce the speed limit to 5kmph?”

          Nice straw man argument there.

          “…I’m somewhat surprised at your assertion that I prove my evidence.”

          You made a wild claim about how a minor slow-down in traffic on residential streets would cost billions, simply billions! I think it’s entirely reasonable to ask you for your evidence. Kent provided links to his sources and a concise and accessible summary of the research.

        2. We don’t have to guess about these things. They are well documented. For example in this study by Monash in Melbourne:
          http://www.monash.edu.au/miri/research/reports/muarc276.pdf

          “A hypothesis that is investigated in this literature review is that a reduction in average travel speed brought about by reducing urban speed limits, is only likely to have a marginal impact on travel time. Research tends to support this notion given that average speeds are influenced by many other factors”

        3. Matthew; bollocks. As I explained above rushing at 50, 80, or 100kph to the next set of lights will not speed your journey nor save you time. All it does is enable you to burn more fuel, use up your brake pads quicker, and increase the the likelihood that you’ll kill someone along the way. There is no cost to lower urban speed limits and much to gain.

        4. Refuting bullshit like this claim from TRM takes longer than it is worth. Think of all the change we could be working on instead of answering crazy statements like this?

    3. ” attack vehicle speeds?” Says everything about your paranoia doesn’t it? Attack?
      We are in New Zealand and it’s spelt “centre”.

  5. There is no centre lines on my street and it is really annoying. Cars and trucks park on both sides, cars drive way over the centre of the road to avoid the parked vehicles to the point that sometimes you need to stop and wait for an oncoming car to pass or risk crashing. The traffic is completely unpredictable to cyclists and pedestrians crossing the road. Cars may be going a little slower but I doubt it is safer.

    1. That’s because loosing the centreline only is not going far enough. Street width of 6m or less and parking bays resolve the remaining issues. This is proven to work.

    2. “sometimes you need to stop and wait for an oncoming car to pass or risk crashing” – Oh my goodness!!!

      An Auckland motorist had to momentarily stop their car, delaying their journey by perhaps up to 10 secs. BILLIONS, maybe TRILLIONS of dollars in productive time lost that he could have spent sitting at a red light.

      And to think people are worried about ISIS and Ebola when problems like this are in the world.

  6. It’s not for any long period of time. The Dutch use 30 kmh streets extensively. Usually you wouldn’t have to travel any more than 400m or so to get to a 50 kmh ‘main road’. The 30 kmh limit, aling with no lines and street narrowing also enable people on bikes to safely use the street. Reduced vehicle speeds also lowers road noise and reduces the risk to pets, wayward children etc.

  7. Speed limits on residential in California are 25 mph ie about 40 kph. Generally observed and doesn’t seem to traumatize anyone overly. Just as much a car-obsessed culture as NZ, so 30 or 40 kph could easily work

  8. In the Philippines no road markings means its a free for all road and it can at time mean 1 lane becoming 2 lanes and so on. Take a look however about what happened when a place deregulated the road rules. Everyone drove safer

  9. I am a driver and a cyclist. I alternate between the offices I work in having either a 120km+ round trip car commute or a 50k round trip cycle commute so I see plenty of the best and worst of NZ driving and one of my most interesting observations is the number of drivers who would rather close shave a cyclist than cross over the centreline to provide a little space. The centreline is treated with a degree of sanctity I just cannot fathom. It’s a bit of paint on the road for Peters sake. SO I WHOLEHEARTEDLY SUPPORT this proposal. Get rid of the paint down the middle, anywhere other than the open road. And WTF with no overtaking yellow lines in suburbia? Go the nanny state. The paint on the edge is important though as it is the best thing to focus on at night when an oncommer doesn’t dip their lights.

  10. The council seems to be wasting a lot of money on speed humps and other speed restriction efforts when a simple change to the speed limit would probably have a much bigger impact at a much smaller cost (and frankly will be much less annoying). Sure, when new streets are being designed or streets are being relaid lets make sure we use current best practices, but it would cost a fortune to retrofit all of our current streets, money that could be better spent elsewhere.

  11. Some local experience where this and other techniques were trialled in Point England a number of years ago.
    http://www.mackieresearch.co.nz/self-explaining-roads.html

    The “Self Explaining Roads” (SER) concept is about making roads safer and more user-friendly for all road users including motorists, pedestrians, cyclists and residents. This is achieved by designing slower speed environments in local streets and higher levels of delineation and amenity on through roads. Through a team consisting of TERNZ, Waikato University and Auckland City Council, Hamish Mackie managed the research process for a large-scale SER intervention study in Point England, Auckland.

    Key elements of the SER design for the area included a target design speed of 30 km/h for the local road category, with increased landscaping, and community islands to limit forward visibility, and removal of road markings to create a visually distinct road environment. In comparison, roads categorised as collector roads received increased delineation, addition of cycle lanes, and improved amenity for pedestrians.

    Approximately 7 km of roads received treatment. Speed data collected three months after implementation showed a significant reduction in vehicle speeds on local roads (with mean speeds at or below the desired 30 km/h design speed) and increased homogeneity of speeds on both local and collector roads. The objective speed data, combined with residents’ speed choice ratings indicated that the project was successful in creating two discriminably different road categories.

    A bigger study is now underway in Mangere
    http://www.futurestreets.org.nz/

  12. For a rural road, a centre-line is the single most effective safety measure one can implement. However I can see that it might give the impression of a wider road and thus encourage higher speeds. Normally, the wider the road appears to be, the faster people drive. One way of making the road seem narrower would be to paint lines at the sides of the road just ‘inside’ the area where people park – as on the first photo (but maybe closer to the centre).
    By the way If you don’t know the meaning of a continuous centreline, I hope you don’t drive.

  13. A couple of links about both removing centrelines and slowing speeds.

    This video was on 7 Sharp and had a reporter (obviously very much a car person) set out to demonstrate how “crazy” the 30km/h zones were there and how much time it would cost her. To her shock she actually got to her destination faster travelling at 30km/h:
    http://tvnz.co.nz/seven-sharp/drive-slow-video-5666200

    Then this link I have put up before. It is about transforming a suburb of Utrecht that was built during the Dutch car crazy period (yes, they had one) and so was not designed with cycling or walking in mind. One of the simplest things they did to increase (counter-intuitively for a traffic engineer in NZ who want every street to be a de facto motorway) was to half the width of the street and remove the centre lines – as well as some modest speed bumps:
    http://bicycledutch.wordpress.com/2013/08/08/making-a-1960s-street-grid-fit-for-the-21st-century/

    You can see how much friendlier the streets seem after this transformation. And, critically it appears for Auckland, there was no parking removed – in fact if anything there was more parking available.
    There are currently big problems getting cycle infrastructure on Beaumont Street in the Wynyard Quarter because of course all commerce will grind to a halt if a small amount of parking is removed. I ask why not narrow the street (it should be a slow street anyway) creating room for separated cycle lanes and leave the parking where it is. Maybe even just make the whole area 30km/h. It is likely to add 10-20 secs to a journey over the whole length of the street.

  14. One of the easiest improvements that I would like to see is every time new work or renewal work gets done the standard is lifted, for example. In Papakura we have a road called Butterworth Ave. It connects the Gt south Rd and Opaheke Rd both are major through route with traffic lights. Butterworth was being used as a rat run to get through the lights. AT put in 4 speed humps to reduce the speed to 20kph. At the same time why didnt they take out the centre line and put in protected cycle lanes on both sides further putting the squeeze on the speed. Easily done and a huge improvement in safety. Every time tarseal gets renewed thought should be put in to how can we make this better.

  15. The Tasman District Council is now in year three of removing centre lines on low volume rural roads as the reseals takes place. We are also removing the edge marker pegs. The world was going to stop and everyone was going to be killed was the noise from the ratepayers. Must say it was a rough ride for the first two years as we dealt with public issues however the world did not freeze over and we now the rate payers have started to live with the new look. No accidents appearing due to not having markings so far.

    We now mark out of context curves and intersections only on these rural roads and have increased curve signs where speed value differ to rest of road speed values.

  16. Talking of speed limits in towns, when you’re on a long distance road trip have you noticed that the people who hold you up by driving too slowly on the open road are also those that race through towns without slowing down? i.e. a complete lack of awareness of the appropriate speed in a given location.

    1. I once did a trip from Muriwai to Albany spent the entire journey behind a car that did 70km/h regardless of the speed limit, most frustrating drive ever.

  17. Much of the friction between traffic and cyclists in the urban environment occurs not because streets themselves are too narrow to accommodate both, but because parked vehicles act to reduce their effective width. A narrow, 8-metre carriageway (4m kerb-to-centreline) generally allows enough room for a car to pass a cyclist with 1½m separation, without encroaching on the opposing lane.

    But you take even a 12-metre wide carriageway and dot it on both sides with parked vehicles, and hey presto! – you have just created safety-nightmare for cyclists and a source of irritation for drivers. A 1.8m-wide car parked 200mm out from the kerb immediately reduces the lane width by 2m. Add to this a 1½m clearance-zone which cyclists must sensibly allow to be out of the reach of doors swinging-open, then say 0.75m for the bicycle itself, and that is 4.25m of lane-width already consumed, with moving traffic still insistent on overtaking!

    What was a reasonably-safe and low-conflict environment WITHOUT ON-STREET PARKING becomes a major hazard and cyclists’stress-zone BECAUSE OF ON-STREET PARKING. To those who accuse cyclists of being an impediment to vehicle movement – this common situation is NOT THE FAULT OF THE CYCLIST! The imposed costs and hazards of vehicle-parking are yet another externality of-, and hidden-subsidy to-, the car-based transport system.

    In our risk-averse and safety-pervaded culture, what is being done to address this anomaly? What is being done to even acknowledge that a problem exists? Nothing as far as I can see, because unlike rail-safety, or industrial safety, or Pike-River-reentry safety, nobody is accountable for road-safety. Rarely do senior butts get kicked when a road accident occurs, even those butts whose decision-making directly contributes to the environment which produces the hazard. Hopeless!

  18. I was living in Wellington when 30km/h limits were introduced through several of the local shopping centres around the city. These seemed to go down really well with the public. Pedestrians and cyclists felt safer. The areas were in environments where most people would’ve only driven around 30km/h anyway- places with lots of pedestrians, busstops, on-street parking etc. Reducing the speed limits probably just brought down the speeds of a small minority of people zooming around at 50km/h. These were only introduced in small, well-defined activity centres though – perhaps that’s a good way to start before looking into area-wide reductions.

  19. The role of the two Croydon streets is not at all modest: Wickham Rd is the main road to Bromley, and Brighton Rd the very busy main road between London and Brighton. Both are busy bus routes. The latter carries an average of 20,000 vehicles a day, including over 500 buses.

  20. I had a look at the Wickham Rd streetview – were the cycle lanes, red edge markings, and speed cameras there before the centre line was removed? i.e was the centre line removal the only change made, or part of suite of a changes?

  21. Centrelines have no place on most local roads. People have known about lane widths and markings causing speed for decades. When NSCC rebuilt my street 10 years ago I talked to the engineers involved and insisted there be no centreline except a short bit around a blind bend. But the worst offenders you will find are the bus ops people who insist on wide lanes on any local that is part of a bus route. The first example above looks like it was built as a collector road and the second has a no passing so it must have poor visibility due to vertical curves and a local resident who has complained. It now looks like a state highway.

    As for removing all markings I think that would only work if we got rid of ACC and brought back personal liability. At the moment if you hurt someone then you don’t pay them anything.

      1. But the difference is Germans respect rules in an obsessive way. In the US they sue the bejesus out of each other and even in Australia you can make someone pay if they are negligent. But here we have a no fault ACC system that replaced personal responsibility. We could remove all of the controls and people will drive just as badly if not worse. Why do drivers pass cyclists with cm’s to spare? Why do hoons blast along quiet streets at 3am? Why do people close up gaps as soon as you indicate a lane change in NZ? I think part of the reason is we are not held accountable. We have insurance for our cars and the state absolves us of paying for anyone we maim. So people can drive badly without caring.

  22. In early 1900’s a Drs wife in Indio,California painted centerlines on main road thru town
    because her husband was treating so many injuries from head on auto crashes.

  23. Take away lane markings,centrelines etc will make it even harder for vehicles with safety features such as lane guidance to operate.Clearly this technology will make it’s way into mainstream cars in the next decade.

  24. The average length of road section without a centre line was less than 400m. How much of the reduction in speed is caused by the sudden and temporary absence of the centre line? In other words did drivers respond to the change of centre line vs its absence?

  25. The TVNZ exercise, while interesting, is hardly proof that a lower speed limit leads to shorter travel times. One trip at each speed is nowhere near the required sample size.

  26. As a proud kiwi, but probably more importantly in this context the author of the original Transport for London study, I am quite pleased to see our report getting coverage back home.

    I would like to clarify a couple of points in this article though, to improve the context. All three sites are on the ‘Transport for London Road Network (TLRN)’. These are the strategic routes through London, and carry the heaviest traffic – comparable to NZ’s State Highway network. They do not have a ‘modest role in the transport network’, they are essential to the transport network. Whilst making up only 5% of London’s roads, they carry 33% of London’s traffic. For these particular sites, daily traffic is in the order of 20,000 – 30,000 vehicles. Speed reductions have been found in the past from removing centre lines on quieter roads, we were interested on the effects on the big boys of the road network – and got some fairly compelling results.

    To answer a few points raised, accident statistics have not been analysed, as the work has only recently been done. We intend to revisit in ~ 3 years when we hope to be able to check whether there has been a change (statistically). The environmental and economic impact of speed reductions in cities has been done to death in numerous other studies, so we did not consider looking into this.

    We’re also looking to go back after 1 year and remeasure speeds – to see if the ‘hang on, something’s changed’ effect was responsible for the speed reduction rather than the actual non reinstatement of markings.

    We tried to measure the speeds in the middle of the test sites, to try and mitigate the immediate effect of the change from centre line to no centre line.

    As a result of this trial, the technique is being used on a number of other sites, and continues to be used. We are monitoring before and after speeds on the majority of these sites as well to further build our understanding.

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