This post originally appeared on the site of Sandfield and is by Mustafa Hasanbulli. Sandfield are the wonderful team who developed and maintain the blog for us.

Auckland traffic has always been a hot topic in NZ. There are regular news articles about the woes of Auckland drivers as they face increasingly congested motorways, and it’s always a popular election issue.

Have you ever wondered what the traffic would be like if you leave now, or in another 30 minutes? For those of us driving to work, misjudging traffic flow and journey times can mean we’re late for that important meeting or miss those early bird car park deals.

Most of the time we can guess the traffic by previous experience e.g. if you are travelling to the city centre, it is fair enough to assume that it would be jammed in the morning and in the afternoon, as the majority of us start work between 7 and 9am and leave between 4 and 6pm.

This blog post is not about how bad the traffic is, or how we can solve it. It’s a fun experiment we set up out of curiosity to see if there was anything behind our assumptions. This isn’t a full blown modelling/simulation of Auckland traffic. If anything, we hope it shows how easy it can be to extract simple insights from publicly available data sources, using those insights to help with everyday decisions.

What we did

Google Directions API is a great tool to get estimates on how long it’s expected to take to reach a destination. We set up six Google Sheets spreadsheets with a simple script to make calls every minute to the API to retrieve travel duration estimates to/from three cardinal directions (north, west and south) to/from the CBD. As expected, there was a noticeable morning and evening rush.

Observations from Auckland commuter traffic

  • The southern motorway seems to have very stable morning and evening traffic
  • People living in the south seem to travel earlier than everyone else
  • The northern motorway is the most chaotic in the morning (The Auckland Harbour Bridge will contribute to those higher travel times) and quietest in the evening
  • It is worse to travel to the city between 7am and 8.30am. It is also worse to leave the city centre between 4pm and 6pm.

More interesting observations can be made if we break down the day-to-day travel times for each direction. Below are the plots representing weekday travel duration estimates:

From the plots above, we can make some observations:

  • In most cases, getting to work on Mondays and Fridays has a similar pattern. We could assume the later Monday start could be because it’s more challenging to get out of bed the first day after the weekend. People may start later on Fridays or have the day off or work from home.
  • We stay later at work at the beginning of the week and leave work earlier closer to the end of the week

All three directions exhibit the same behavioural trend: we seem to be really eager to leave earlier and earlier as the week goes on.

As we leave work earlier, travel times increase as well. So, leaving early might not be the best option.

If we look back at the overall travel duration times for three directions, we notice something else. Regardless of the direction you are going, if you are getting into the city in the morning or you are leaving the city in the afternoon, every half an hour you are late, you add a further 10 minutes to your total travel time.

This might sound like we are suggesting to leave early. Actually, we are saying the opposite. Leave later because travel times decrease faster after peak hours.

There is a linear relationship between the time you want to leave and how busy the traffic will be at the time

e.g. If you normally leave your house at 7am and you are planning to leave at 7.30am, this will add another 10 minutes to your total travel time. So, every half an hour is equivalent to 10 minutes additional travel time when getting into the city in the morning hours, and leaving the city in the afternoon.

Tips for Auckland commuters based on this data

  • Don’t travel at peak hours if you can avoid it. These are: 6.30am – 8.30am if you are getting into the city, and 4.30pm – 5.30pm if you are leaving the city.
  • We are causing the traffic jams on the southern highway by leaving way too early on Fridays, which defeats the purpose of leaving early
  • Getting in at 6am and leaving at 3pm will give you nine working hours with the shortest travel times if you are travelling into the city in the morning and out in the afternoon
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36 comments

  1. Really interesting post. Especially the friday phenomena which I can attest to. I suspect it would have a little to do with lots of people fleeing Auckland for the weekend who don’t normally use the southern.

    For two years I did 7:30-4pm by train. Now I do the 6am-2:30pm by car. Mostly freeflow traffic. Save an hour a day compared with the train. Costs twice as much though. So it’s a money/time trade off. If I had to work normal hours, I’d take the train.

    1. Yes, I imagine that will be the main reason for the early bulge on Friday’s. I often try and get away around 3pm on Friday when leaving for a weekend only to become part of the problem!

      1. I think another reason for the early bulge on Fridays might be that lots of industrial work places start and end early, and offer overtime M to Th, but not Friday.

  2. It simply doesn’t make sense that the Auckland harbour bridge contributes to increased travel time on the northern motorway in the morning. There are five lanes on the bridge heading into the city in the morning, giving it more capacity than just about anywhere else on the Auckland motorway network.

    How can it be a bottleneck when it is two lanes wider than the motorway that leads to it?

    My experience is that the bridge is almost always free flowing, and while there is certainly congestion on the northern motorway it seems to be caused by the sheer volume of traffic on the motorway north of the bridge, exacerbated by the large numbers of cars joining at Northcote, Esmonde etc.

    1. The bridge itself isnt the bottleneck. Its the two very large inflows just before the bridge, at Northcote/Onewa Rd and and behind it Takapuna/Esmonde Rd. The lanes are at capacity before those points so adding extra cars there causes the bottlenecks

    2. I assume merging issues from all the on ramps slows things down.

      Also, I think psychologically, people stuck in normal traffic just drive slower because they are used to things being slow.

  3. I’m curios, did the test use the same distance on all three directions and, if so, what was the distance?

    In my own observations from travelling into the CBD on the Southern MW, don’t be near spaghetti junction near 06:00 unless you want a lot of agro bad driving. There seems to be a window from about 05:45-06:15 where the drivers are more aggressive and exhibit poorer skills. I posit that this is because people on the road at this time either start at 06:00 or 06:30 and are running late. Glad I don’t do that trip any more.

    1. The actual distance to the destinations are not the same. They are fixed random addresses at those destinations. However, we have stripped the effects of different distances. In other words, you could say they are all the same distance to the CBD.

      1. Hi Mustafa, thanks for the reply – I was wondering specifically about where on the southern you were referencing, as I notice that there are some parts that do not conform with the data. Ellerslie for example is busy heading north until after 10:30, being heavy from at least as early as 06:30. Ellerslie is an interesting case, as during shoulder periods the traffic evaporates after Greenlane.

        So to rephrase my question, could you bracket the distance (5-10k, 10-15k, etc)?

        1. The distance to the destination for the south is around 14.7km. You are right that traffic gets lighter after Greenlane. Google Directions API estimates the time spend in traffic to reach a certain destination. So, the final time estimate is a cumulative figure meaning the time you spend in the traffic will increase with the distance. This is the very reason I chose to re-scale the data to get rid of the possible issues introduced by different distances.

  4. Fascinating. When was this done? For future publishing, can you label the three diagrams that split the data into days of the week as N, S and W?

    I’m trying to understand why the travel times are similar morning and night for the S direction, but for N and W they are quite different – and opposite to each other! So for the northern commuters, morning is worse than evening, and for the western commuters, evening is worse than morning.

    Any ideas? I hardly think people are coming into the CBD via the northern mw and then leaving via the western… Do the inner west go into work so early or late that they don’t affect the commuters from further west in the morning, but in the evening both inner and outer west residents leave work at the same time?

    Or is it somehow tied to the discrepancy between different on and off ramp data we noticed once?

    If done since the WC, do southern commuters or freight from the south take their pick of SH1 or SH20/SH16 depending on time of day, and balance the morning and evening this way? Which could have knock-on effects for the western commuters…

    1. That is an interesting pattern you picked up. Very strange.

      If I were to take a stab, I’d say that people commuting from the west heading out can head south via waterview or SH1 and head east via the port or head north via SH1. When they all come home they all get stuck on the same stretch of SH16. Hence why it is pretty bad in the evening.

      Inversely for those commuting from the north, in the morning as you head south, you really have only one option, no matter your destination. Head to the bridge. So as you head south, everyone is piling onto the same section of SH1. In the evening, the bottleneck is every onramp and spaghetti junction and the bridge to some degree. Once you cross the bridge, everyone is getting off of SH1 as you progress further north. So it isnt as bad as the morning.

    2. I think the order could be north, west and south. That would match the one above them.
      Maybe the west is stuffed in the evenings because some plonker at NZTA put up the wrong signs in the Waterview tunnel. They indicate Wellsford via the Northwestern rather than via the Northern despite it being longer in distance and travel time that way.

      1. Ah, you could be right. I was trying to match them too, but I think that Friday bulge threw me… which of course brings all sorts of other things into play, but probably highlights SH1 as being the reason overall?

      2. Yep. It is North, West and South. I think guys at the Greater Auckland missed the titles from the original article 🙂

    3. Yes interesting the difference. Could be to do with just the layout, number of lanes and number of off ramps vrs on ramps etc. North heading into the city is the easiest to visualise with all the on ramps then converging into the bridge then just a couple of main off ramp city points….which take time to distribute the cars to parks etc.

      Coming from south into the city there are many off-ramps compared to the west or north origin travellers & so clears faster?

      West not sure, sun strike? – more accidents? position of the motorway works? could be just in all these cases people train themselves to leave the earliest they have to in the mornings but at the end of the day it’s a lot more fixed….or maybe it is for Westies…no train/NEX line that follows the motorway like south & north have?

      1. Sun strike will be an issue. Northern motorway and approaches is noticeably worse in morning for about a month in spring and autumn. Reason being – drivers hit their brakes as they are sun-blinded turning into St Mary’s Bay.

        Really interesting stats but it posits that all the congestion is heading out of the CBD. In my experience heading towards the city centre from both the south and north in the evening seems as bad as the other direction. West seems more immune to this

  5. 6am and 3pm, would this also be the same for 9am and 6pm? Staggering work hours is probably helpful for traffic anyway. But the later start might suit for those who are night owls and/or don’t have kids, while saying the same thing.

  6. Is there a lot of difference between peak and counter-peak? My experience has been that counter-peak to the north, there is almost no congestion in the morning, but significant congestion in the evenings.

  7. I never understood why the evening peak is anywhere near as bad as the morning. In the morning lots of vehicles are trying to squeeze into a few places (city, newmarket, onehunga, east tamaki, etc) – kind of like entering a funnel. But in the evening the vehicles are leaving that funnel going to many different places – shouldn’t this be much quicker?

    1. Tired drivers adding to it – accidents, missing light phases, more start stop not “spreading the jam” on the motorway. I notice it seems more dangerous on a bike in the afternoon peak than morning. Could be that people just leave more all at once…combined with errands on the way home.

    2. As I watch NW each afternoon I’d say the issue is that each of the off ramps is effectively a funnel (most of the with traffic lights on exit too), once the funnel gets full – its starts pushing back onto the motorway and at some stage all lanes start to crawl (I suspect due to late lane changes and queue jumpers) and that’s it. It gets better past the off-ramp but than it hits another bottleneck on the next one (or reduction of lanes).
      On NW going West:
      – Great North – no lights, but heavy traffic
      – General lane changes due to lanes from tunnel being the ‘through’ lanes and the ones coming from the city dropping off
      – Reduction of lanes past Rosebank
      – Traffic entering at Patiki and leaving at Te Atatu (lights and general lack of capacity on Te Atatu Rd block exist here)
      – Traffic leaving at Lincoln rd hits similar problems
      – Reduction to two lanes past Lincoln.

      So one could say there is a fixed number of ‘destinations’ too and they’re all congested.

  8. “We are causing the traffic jams on the southern highway by leaving way too early on Fridays, which defeats the purpose of leaving early”

    I don’t think it defeats the purpose. Surely the purpose it to get home earlier. Sure, your journey will be longer if you leave at 4pm, but you’re still going to get home earlier than if you left at 5:30pm.

    1. I think the purpose has been set at reducing the amount of stressful, life wasting time sitting in a car in congestion. But interesting insight, there are significant numbers of people who don’t mind sitting in their car in traffic and aren’t as concerned about restructuring their arrangements to make their days more productive overall.

      1. ….or they can’t. Not everyone can set their own hours or can flex that time to make that happen. Too often this blog is filled with others assuming that other people have the same time freedom as they do.

  9. Why no comment in the blog about leaving/working later? I know it’s not for everyone, but I’ve been leaving after 9am and and after 6pm for years, it’s way less stressful and suits me fine. That goes for active modes in the city too, not having to deal with angsty drivers trying to get across every road or driveway.

    1. Yes, one of my sisters does that too. Jessica mentioned it above. And I’d say there must be quite a few people who do. I’m not usually out on my bike at 7 pm, but I was last night. I couldn’t believe the traffic coming along Meola Rd at that time: steady state, no breaks in the line, and from where most of it was turning, I’d say it was local Pt Chev people. Yet at the other end of Pt Chev, on Great North Rd, there was much less traffic.

  10. What the graphs don’t show is the huge volume of traffic travelling north on the Southern Motorway during the evening rush hours. Sometimes it can take up to two hours to travel between Highbrook and Spaghetti during the afternoon commute, but because it is going in the opposite direction to the computer programming it just doesn’t show up in the figures. Regarding the Friday drop in peak hour volumes, a lot of factory and construction sites work 7 am to 5 pm Monday to Thursday, and knock off around 2 pm on Friday.

  11. I have noticed on the graphs that the movements of the vehicles all look like a small Japanese/European style car or is that a coincident ?

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