Last week, I took a high-level look at the opportunity cost associated with Auckland’s car-centric transport system. Simply put, cars use up lots of land, and public transport, walking, and cycling don’t. At a time when we’re struggling to find space to accommodate the city’s residential and economic growth, this is likely to be increasingly inefficient.

For example, here’s a graph that shows, roughly speaking, the last 50 years of trends in traffic volumes (using the Auckland Harbour Bridge as a proxy) and land values (using national house prices as a proxy). In the last decade or two, demand for intensive land use has far outstripped demand for driving:

AHB traffic volumes and real house prices, 1961-2014

However, this isn’t always acknowledged in the activities of transport agencies. As Matt highlighted two weeks ago, Auckland Transport is currently proceeding with a plan to knock down a house (on the bottom left corner of the intersection, shaded in magenta) for an intersection widening project:

Chivalry Rd Intersection Future

A bit earlier, Stu also pointed out an intersection design down in Hamilton that seems quite hazardous to people on foot. Now, there are certainly reasons to redesign – and even widen – intersections. But what worries me is that intersection layout sometimes seem to be on auto-pilot, without any deep consideration of the conflicting values at play or the opportunity costs associated with particular designs.

Take, for example, this intersection at the junction of St Johns Road and College Road in Remuera. It’s large. Very large. Although there’s only a single lane in each direction on the roads in and out of the intersection, it widens to implausible dimensions in the intersection itself. I can only imagine what it’s like to try to cross the intersection on foot.

st johns and college road

I asked my friend Lennart, who originally spotted this intersection, to show me how things could be done differently. He quickly sketched up a simplified design – shown in the green and magenta lines – that eliminated the big islands and the split lanes but still left enough room for buses to turn smoothly.

(Caveats: This is not necessarily a better design from a traffic engineering perspective – just a more space-efficient one. As we haven’t looked at traffic volumes, it’s difficult to say whether a signalised intersection or other safety treatments would be required if the slip-lanes were taken out.)

Overall, we found that there would be up to 2,000 square metres of space left over if the intersection was downsized. That’s enough space for three or four reasonably-sized houses on reasonably-sized lots.

Is this expenditure of space worth it? Would it be better to narrow the intersection and sell off the residual land for housing? Possibly. Possibly not. But no matter what the answer is, I hope that those questions are being asked of Auckland’s road designs.

What do you think of the space occupied by our intersections? Good, bad, indifferent?

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  1. Driveways from those houses would be problematic. However slimming the intersection and using some of the extra land for cycle lane bypasses would be nice.

  2. From what I understand, long term this will be a set of signals, but I think that is a long, long way off.

    Aside from the fact that buses probably wouldn’t be able to make those turns without hitting each other, space efficiency isn’t the only factor. Yes if space were the only consideration then we would have smaller intersections. The other factors would be cost of installation, cost of maintenance, operational efficiency, all road users and most of all safety.

    When this was put in, land was cheap, so its larger than in needs to be. Now the land is worth a lot more it does suggest we could make better use of it. If we were building a new intersection here, it would probably be signalised because it would be cheaper than land purchase. But now that AT owns the land, there isn’t much argument because signals would still cost a lot.

    A roundabout is less costly to maintain then a set of traffic signals, by a large margin I would suspect.

    A roundabout is more efficient for moving traffic. Most people in this area are wealthy and drive cars everywhere so there are lots of cars moving through there. Putting in signals would drastically reduce the number of cars that can get through here at peak times and so you would get a lot of congestion and a lot of complaints from local residents because there aren’t that many alternate routes. Also buses at peak times would get stuck at this intersection too, unless you want to use up more space to cater for them as well. Traffic efficiency is often the most important factor in design regardless of whether it should be the most important factor.

    In terms of safety the roundabout will be far safer for cars than a set of signals because of the reduction in conflict points and reduced speeds. Of course that does depend on the design of the roundabout which NZ isn’t that great at. They improved this one with plantings to slow vehicles down. But we also know that roundabouts are also difficult for pedestrians to cross and dangerous for cyclists. So it is a trade off.

    I know this is just a rough idea, but we are forgetting pedestrians and cyclists. These are a must at new intersections. Adding in cycle lanes and generous footpaths on both sides of the road would dramatically increase the footprint of the intersection. Then there are also the existing driveways you need to cater for. So overall, even if you did put signals in using minimal space, the space saved would actually be much reduced.

    You raise an interesting point about the size of many intersections and if this is needed. Probably not in many cases given that we cater for peak times, but not the other 18hrs of the day. I don’t think we should be doing this, but we do. It is a key point of consideration for new intersections, but retroactively shrinking intersections after the fact wont really release useful areas of land. If anything you will just get wider footpaths or some place to plant some flax or something.

  3. Nice in theory to score back every inch of road you can, but in reality many of these intersections were designed to take into account future increases and avoid using traffic lights, thus improving flows which is what moving traffic is all about. If the intersection were reduced in size there would be backlogged traffic (traffic lights), increased noise, pollution, travel times (for buses too – unless you want a bus lane too, and cycle lane?) etc and maybe no desire for anyone to live on the reclaimed land. Auckland isn’t Hong Kong or Singapore so the obsession with utilizing every inch of land to house increasingly compressed numbers of people is not necessary. There is no wasted expenditure as this intersection and others like it already exist – already paid for many years ago. Impeding flows helps no-one.

    1. “Impeding flows helps no-one”. It depends. It makes driving a less attractive option, and that’s got to be positive.

      1. Well, no
        The purpose of the transport network is to move people effectively and efficiently
        If the end result is a less effective and efficient network then you’ve gone backwards. Fewer cars is not a good in itself. if buses, trains = more effective and efficient then more of them
        But the first rule: do no harm. The result should ALWAYS be faster, safer flows (whether car bus or hovercraft)

        1. Early Commuter: you see, I totally disagree. If your only aim is for better traffic flows for cars, then you are right. But people live in cities. People, not cars. If the aim is to have a better environment for pedestrians, then the best thing to do is to actually have total congestion. Cars grind to a halt, and then pedestrians can walk freely.

          For instance: i work right next to State Highway 1. When car traffic is flowing freely, and SH1 is “working”, then it is a nightmare for pedestrians. We can’t cross the road. Timings of the lights are set at looooooong intervals, to allow as many cars as possible to flow past. Maximum annoyance to pedestrians, to those of us that live here, work here, etc. The cars are just passing through.

          But when car traffic gets “bad” then life is so much better for us pedestrians. We can walk freely across the road, which is now only impeded by large metal sculptures sitting stationary on the highway. Pedestrian life actually gets much better when there is maximum congestion. Have a think on that….

        2. Cars require lots of resources to produce, have a large negative environmental impact due to their production and ongoing emissions, consume fossil fuels and are very expensive to buy and run, creating a huge financial burden for people. So fewer cars is a good in itself.

    2. Good point Ricardo “intersections were designed to take into account future increases”
      NZTA web site tells us the benefits from the near BILLION DOLLAR Waikato expressway Hamilton section will
      “Reduce traffic congestion and improve safety on Hamilton’s local road network by significantly reducing through traffic”
      The Waikato Regional council asks for urgent upgrade to Hamilton intersection because future
      “congestion around this roundabout as a result of the completion of the Waikato Expressway”

  4. I was waiting for this post to turn up.

    That College Road and St Johns Road(s) roundabout works and works well – better than many signalised intersections carrying similar or less traffic can and do in the area.

    It works well as a roundabout because the traffic flows from all 3 directions are somewhat tidal but mostly equal in volume with random breaks – so no one direction dominates the flow and other roads can cross even when the traffic is heavy. Yes tailbacks do occur down College Road and St Johns roads (leading from St Heliers Bay road) at peak times, but tailbacks are usually less than traffic lights would impose.

    The local Board and residents associations (and AT) have reviewed this as part of the Corridor Management Plan as the AT suggested plan of a simple signalised intersection, but that simply won’t work in practise. Because of the semi-tidal traffic flows and resultant tailbacks on existing roads will mean this becomes a bottleneck in short order if lights are installed.

    Also, that back of envelope design has absolutely no cycle priority or Copenhagen style cycle slip lanes. Given this is now in the GI “local cycling” circle for improvement of cycling to GI station as per the UCF announcement last week and is also a key route to access the Tamaki Drive to GI cycleway cycling via Copenhagen style lanes at this intersection should be prioritised. Land there is better given over to this use than freed up for a “pocket park” or a few houses.

    The design shown also ignores the fact that that route is a the Over Height/Over Dimension route for the Eastern Suburbs, and requires a clear roadway carriageway of 11.5 metres and 6.5 metres in height for such loads. Thats is why the roads each way leading into it are so wide to cater for this (NZTA) mandated requirement.

    It should also be noted that there are no pedestrian crossings here currently because there are no natural desire lines (and not just because of the roundabout either).
    All the crossing desire lines are 200m further away on each road and making pedestrians cross at this intersection instead of at the more appropriate places they do now would impose a distance penalty of some 400 metres per road per pedestrian to any pedestrian and will only encourage unsafe crossings mid-block if existing crossing points are not left in place or improved.

    As for land wastage, aerial photos from the early 1950s show this intersection existed more or less in its current form back then and then this was country side so land was dirt cheap.
    However the reason that roundabout exists in the form it has because it was intended to be a intersection used by Trams. Trams which terminated at the adjacent suburb of Meadowbank since 1933 or so and which would have been extended further east but for WWII no doubt. But because of WWII and the demise of the trams the tramlines were removed that never happened.

    However, the local board is being asked by residents to consider asking AT to not preclude the option of LRT coming back to Remuera road and possibly all the way to GI.
    And preserving the land at this intersection is a must to allow that as this is a key intersection along that potential LRT route.
    It is not a priority route for LRT according to AT, but as its going to reach a catchment similar to Dominion Road and will be a spur line off the Onehunga line which will run through Newmarket, it will proably happen in the next 50 years for sure.

    And when it does, we don’t want to have to buy up and demolish buildings because some short sighted person in council decided to flog the land for a few houses.

    Lastly, this corridor is in a high noise and air pollution arterial zone in the UP, using the freed up land to build a few houses on is not going to solve the housing crisis.
    But it will expose the occupants of any of those built houses built there to very high levels of noise and pollution because of their closer proximity to the flows than other residents.

    Doesn’t mean it can’t be improved – but not every intersection is broken so not all need fixing. And this may well be one (of a few perhaps) that ain’t that broke.
    Removal of on street parking on the 3 roads leading up to the intersection could help the flow a bit.

    1. Excuse me? No desire lines close to the intersection? What about people walking along the western side of College Road wanting to access St Johns Road. Or people on bikes trying to cross the intersection. How will Copenhagen Lanes work here without any kind of traffic control? Certainly not up to a 8 to 80 standard. All I’m seeing is traffic engineer excuses. The intersection is ass for everyone unless they’re in a motor vehicle. End of story.

      Also, this overwidth bollocks is driving me to despair. If you build a motorway, build it to take overwidth vehicles. There is no excuse to build a motorway and then keep overwidth vehicles on residential streets.

    2. If they are asking for future LRT, are they asking for bus lanes and bus priority now? That would seem to be logical.

    3. Tailbacks and traffic lights, which one came first? It could be that once an intersection has long tailbacks in some directions the decision is made to place traffic lights, rather than those tailbacks are caused by traffic lights.

    4. The over-dimension corridor is a big deal which a lot of people seem to be overlooking. No matter how few cars Auckland may end up with in future, there will still be a need to send large loads by truck. If we “optimise” every corridor from the perspective of nothing larger than a bus we will, in short order, become unable to carry such desirable cargo as grid-level wind turbines, or conduct house removals, because there will be no path through which such large loads can travel.
      Even long single-unit LPG tankers cannot traverse many of our side roads, never mind something even longer or much wider.

      1. Yes, but why down residential streets rather than by these really expensive motorways we’ve built? As for moving old houses around the countryside? Not a good enough reason to build unsafe roads.

        1. If you hadn’t noticed, motorways don’t go everywhere. Never will. Have to get stuff on and off them somehow.
          Also, motorways don’t qualify as an over-dimension corridor. Lots of bridges. If you look at the corridors such as Greenlane Rd, St Johns/College Rd, etc, you’ll notice that there’s nothing constructed overhead. Utility lines can be disconnected if required, but it’s really hard to just disconnect a bridge.
          Over-dimension corridors have particular characteristics that motorways simply do not meet, including minimum widths and no fixed overhead.

        2. So every road should be classified as overdimension using that argument. The original intent of motorways was to move lots of large materials.

        3. No, many (probably the vast majority) of our roads do not meet the requirements of being over-dimension corridors. Too narrow, or foot/road/rail over-bridges. Over-dimension corridors are protected from being built into or over, whereas ordinary roads and motorways are not. An over-dimension load can be many metres taller than even the highest motorway over-bridge; the standard maximum height for a vehicle on NZ roads is 4.25m, and an “ordinary” over-height load can be 6.5m before the permitting starts to get really nuts. Many motorway over-bridges are as low as 4.30m.
          Similarly, for length and width, many roads and intersections are too narrow for wide or long vehicles to pass, particularly with the cornering requirements of long vehicles. Even some standard-length rigid trailers cannot fit through a lot of our side roads because of their turning radius, never mind vehicles that exceed the standard legal length.

          Whether or not you think it makes sense, it is the law and it is the designation in place. Changing it is not a matter of nice wishes, it’s restricted by such matters as the laws of physics regarding two objects occupying the same space simultaneously. The motorway does not meet the requirements, and the cost of changing that would be many, many hundreds of millions of dollars; the only parts of the Auckland motorway that are permitted for any significantly (more than 4.25m high and/or 3.1m wide) over-dimension loads are between the Ararimu Junction and the southern end of the Southern Motorway, for loads not exceeding 4.7m high (but no more than 3.1m wide), and SH18 between Buckley Ave and Old Albany Highway (source).

  5. Classic example of the traffic engineering goal of never making a car have to stop. This looks me like a traffic light or roundabout opportunity, and if the widening is for volumes a long, long way off, then save the money and do it then.

      1. No I disagree. In the safest traffic country in the world, the Netherlands, cars have to stop all the time while bicycles do not.

        Cars should always have the lowest priority on local roads. If cars want to move quickly they should stick to the motorways and major arterials. On every other road they should be inconvenienced as much as possible.

  6. The is plenty of unused land in St Johns. Why waste millions of dollars re-engineering something that works surprisingly well. This intersection is close to where I live, and where we walk at night. It is surprisingly pedestrian friendly, and if lacking anything, it is safe areas for cycles.

  7. Less is more

    Intersections should be like F1 race tracks, chicanes or pinch points to slow people down for the tight corners (an intersection), but run-off areas for when you get it wrong, not large solid objects to smash into

    1. Most suburban streets are race tracks already mate. We need more big scary obstacles and *no* second chances. I would like to see steel pillars along every kerb to keep pedestrians safe. And posts that pop up out of the ground when the light turns red to force cars to STOP occasionally.

      Slip lanes are a terrible invention at intersections, nobody looks in the direction of travel, they only look at the stream of traffic. Too bad for pedestrians!

  8. One problem with the San Francisco proposal – you need to make the streets wide enough to get trucks down them to get the materials down to build the houses in the first place, and to get emergency vehicles such as fire trucks down them. We have streets in Ponsonby which are barely wide enough to get a car down them let alone rubbish trucks and emergency vehicles. The residents have it sussed out by parking their cars on the footpaths, but patrons of nearby restaurants run the danger of coming back to find their vehicles with damaged sides simply because because they didn’t take into account to room needed for emergency vehicles.

    1. Ponsonby residents obviously believe their life of entitlement extends to footpaths. The name tells you it is for feet. Parking on a footpath is illegal and will get you a $40 parking ticket.

  9. Peter, do you think your friend Lennart would be able to look at the southbound bus lane just south of the Harbour Bridge on SH1 (between bridge and fanshawe st) – is there any way it could be repositioned to the north side? NZTA tell me that they put that lane on the south side because
    1. Bus operators told them it’d work better
    2. Because of the lanes that buses use on the Harbour Bridge (L3 & L4 – they wouldn’t use the bus lane anyway)
    3. Best use of capacity
    4. Alignment of the roadway approaching the bridge
    5. Balance
    6. Effect on SH1 for putting the lane on the northbound side
    7. It can’t be changed now, because it’s all done now

    I’m not a traffic engineer, but it seems to me that by relocating the bus lane to the northbound side, it would cut the northbound bus times by 1-4 minutes in peak (depending on how bad the traffic is), and would not change the travel times for southbound buses at all… Also I’m not sure about the other reasons, but surely, we don’t have an optimal setup there, do we?

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