Slowest City tag meaningless

The media seem went gaga a few days ago about a new report that looks at the impacts of congestion in Auckland and other Australasian cities. It’s no surprise they reported on it either, transport in Auckland is a common gripe and so the story of Auckland being the slowest city, confirming what many people already believe, was too much to pass up.

But even reading the news articles, it struck me that this was likely another case of the wrong questions being asked but that by in large, the right answers were reached, much like ATAP. Perhaps even more so it wasn’t the main findings of the report that were important but some of the ancillary comments.

The report is by Austroads, a key organisation in the development of road networks in Australasia. Here’s some of what the Herald said about it.

Auckland commuters can groan in agreement with a report that reveals the city has the worst travel times and reliability in Australia and New Zealand.

This is despite having the fastest road in the two countries combined.

Austroads Congestion and Reliability Review measured the levels of congestion and traffic across major cities in Australia and New Zealand and released their findings in a report.

The cities were categorised into groups of similar population size. Auckland was in group two alongside Perth, Brisbane and Adelaide.

In its group Auckland performed worst across “most measures”. These included the highest travel time delay, morning and afternoon peak reliability.

Auckland came out worst in it’s group with an average speed of 77.6km/hr. The other cities were between 82km/hr to 86km/hr. American cities of a comparative size went up to 104km/hr.

The slowest roads were St Lukes Rd, Wairau Rd and Lake Rd. While the fastest were the Northern Gateway Toll Rd (which topped the Australasian list with an average speed of 98.8km/hr), Upper Harbour Motorway and SH16.

By focusing on the speed of commutes, my immediate feeling was that this sounds like a very similar approach taken by Tom Tom and other organisations for their own congestion reports. This proved to be correct as this is what the press release says about the method they used.

The findings are based on an analysis of Google Maps data for 600km of roads for each major Australian city, enabling analysis of travel time along different road segments. The analysis was based on two months of data, comprising of 1km long road segments, with data points taken every 15 minutes, to calculate the six key congestion measures outlined in the report. An econometric analysis was then undertaken to provide insight into the drivers of network performance.

We’ve written before about TomTom’s reports, one of the key problems with reports that use this kind of methodology are that they are based on measuring the variance in the speed of traffic compared to the maximum speed limit allowed on the road. This ignores that roads can be more efficient and flow better with lower speeds, for example a motorway will move more vehicles an hour/flow better if they’re all travelling at 80km/h than 100km/h.

Also importantly, these reports only ever reference vehicle congestion/speeds, not the people using that corridor. Infrastructure like the rail network and Northern Busway allow a lot more people to be moved within a corridor, often faster and free of congestion. We know that 40% of people crossing the Harbour Bridge every morning on a comparatively small number of buses don’t suffer from the congestion those in cars next to them have endured.

But it’s here were we reach one of those right answer to the wrong question points. That’s because while we know that counting the speed of PT and other road users is key if we want a more accurate report, we also know that Auckland is one of the worst performers when it comes to use of other modes, something noted by the authors when they say

Auckland has fewer public transport options, compared with other cities. Plentiful low-cost parking in Auckland encourages commuters to drive.

Looking at the articles also raised a new potential issue with how these kinds of congestion metrics are created, in particular the mention that the Northern Gateway Toll Road was the fastest in Australasia. In short, why would you count a rural tolled motorway. Other than on holiday weekends, which wouldn’t be relevant in this discussion, this road has almost no bearing on the congestion most Aucklanders might experience. But that got me thinking, if the toll road is included in Auckland’s numbers, what else is included, especially in other cities.

So here’s Auckland’s map of the most delayed roads based on their methodology.

And as one example, here’s Perth which comes out much better in the metrics.

And Brisbane

One thing worth noting is it appears these maps are not at the same scale, the furthermost point away from the Auckland City Centre is about Drury, 30km away. By comparison in Brisbane and Perth some of the locations shown are over 50km away from the city centre. This hints at one of the potential issues, there are a lot more uncongested rural highways included in the numbers of other cities compared to Auckland. To be fair, in the middle of the report they do say that the types of roads selected for this report will impact the results i.e. more motorways generally results in higher average speeds.

The report also looks at some international cities as comparisons but oddly they decided specifically to choose cites with similar PT modeshares to the Australasian cities which means cities of similar sizes and densities in places like Europe and North America can’t be compared to see if there’s something cities here could learn if there was a different transport/land use focus.

As mentioned earlier though, despite issues with some of the ways this report has been approached, I do think it comes up with some useful points.

More important that the speed of a particular journey is the reliability of it. If you know it’s always going to be slow then at least you can accept that, or adjust when or how you travel to avoid it. But when that varies considerably every day it can be infuriating. Of course, Auckland fares poorly in the reliability rankings

They also make some very salient points about why Auckland performs poorly. These include:

  • Auckland’s geography, particularly its harbours and waterways, impose constraints on the transport system, meaning the main transport links are confined to narrow corridors
  • Compared with other cities there is a lower level of public transport provision for commuters
  • There exists highly available and low cost parking in Auckland which encourages commuters to drive

Auckland’s geographic constraints forces a lot of people to travel through narrow areas, if only there was a way to move a lot of people without needing a lot of space to do so. Despite what some urban myths would have you believe, that makes Auckland ideally suited to public transport, if was provided it well. This is something backed up to some degree by ATAP, which noted that there are only limited options for expanding road capacity within most of the urban area.

There is no one solution to ‘solve’ congestion but definitely a “more of the same but bigger” approach will not work. If Auckland wants a chance of improving congestion it will need provide better alternatives so the best option isn’t to sit in a car and hope for the best.