Make Good Bus Routes Great

How do we make public transport in Christchurch better? We have several good bus routes in Christchurch that have OK frequencies, some level of bus priority and not terrible infrastructure. I think we need to focus on these routes to get them from just good, to really great. But I’ve been hearing more and more conversations lately that contradict this and so I thought I’d jot down why this is what we should be doing.

In a city like Christchurch, where it’s relatively easy to drive, most trips take longer if you choose to make them on a bus compared to if you drive. And most people in Christchurch have the option of driving, we have one of the highest rates of car ownership in the world. If the same trip takes 51 minutes on a bus or 11 minutes in a car, the vast majority of people will choose the car. For example, this trip from Hornby to Ilam.

However there are some trips where taking the bus is comparable or even faster than driving. This occurs in places that have bus lanes, high frequencies, and traffic congestion. For example Halswell to the city in rush hour.

The graph below shows an equation transport planners use when trying to predict people’s choice of travel mode. It has been derived from observations of real-life behaviour in Christchurch. The horizontal axis shows the relative attractiveness of taking a trip on public transport compared to driving. For most trips the relative attractiveness is negative, meaning that driving is more attractive than catching the bus. “Attractiveness” is a number that’s calculated from a range of factors, but the most important one is the door-to-door travel time. For the rest of this blog just think “travel time” whenever I say “attractiveness”. The vertical axis shows the proportion of people who will choose to make that trip on public transport.

The graph shows that if, for a specific trip, catching the bus is much less attractive than driving, then hardly anyone will catch the bus. An example of this would be the Hornby to Ilam trip above.

For a trip where catching the bus is more attractive relative to driving, then more people tend to catch it.

At the point where driving and bussing are a similar level of attractiveness (zero on the horizontal axis), then we observe about 15% of people will catch the bus. An example of this would be the Halswell to city trip above.

As the bus gets more attractive than driving then this ramps up to 30% and higher.

Note that the slope of the line gets steeper as you go further right. If you improve the bus from being massively less attractive than driving to being just moderately less attractive, you’re still going to find that not many people catch it (left-hand red arrow below).

Whereas if you can find a trip where buses are only slightly less attractive than driving, and improve the buses so that they flip over to being more attractive than driving, you’ll find that you get a big increase in the proportion of people choosing to catch it (right-hand red arrow).

The implication for Christchurch is that we should look at the parts of the city where bus provision is already relatively good, like Halswell, Riccarton, Papanui, and Linwood, and try to amp up the public service offering there so that it flips to being more attractive to bus than drive. If we can do that then we’ll see a big uplift in usage.

And we shouldn’t spend too much of our energy on the places with poor or no provision, like Redwood, Bromley and Sockburn. Investing a whole lot of money in those areas to get public transport from being terrible to merely mediocre – that will not attract people in any meaningful volumes.

Investing more into the areas where public transport is already good, and investing less in the areas where it is worst, might seem counterintuitive and somewhat unfair. It really depends on what outcomes you are looking for. Jarret Walker has written extensively on the trade-off between coverage and patronage.

Personally I feel Christchurch’s bigger failure is on the patronage side and that is where we more urgently need to up our game. To do that we need to collectively accept this principle, forget about creating more mediocre services, and focus our efforts on making our good bus routes great. The only reason to not do this is if coverage (and equity) concerns are more important to you than patronage. That’s a legitimate position to hold, but if that’s your position you need to be honest about it and accept that means investing money in something that won’t increase patronage meaningfully.

Too-Long-Didn’t-Read: If increasing public transport use is our goal (and I think it should be), then we should be focussing our energy into making our good bus routes great, not our terrible bus routes mediocre.

Turning a good bus route into a great one

7 thoughts on “Make Good Bus Routes Great

  1. Great article. One suggestion: put the TLDR at the top.
    And a (lengthy) comment. When Deon Swiggs and I sat down with regional council staff in early 2019 and discussed the [ Zone 0] proposal, the staff’s main concern was that one of the core routes coming from the east (route 5) was at capacity and we thus shouldn’t make bus use more attractive. After a gobsmacking silence, I asked whether they had thought about introducing double deckers (the cheapest way to increase capacity as you don’t need more drivers) but no, this was all too hard. That the same staff gave a completely different reason for their rejection of Zone Zero when asked by a reporter a few days later is beside the point.
    What I’m saying with this is that staff attitude has a huge bearing on why Christchurch public transport is in such a state and not improving. “We couldn’t possibly attract more patronage as the system wouldn’t cope” is something that should just not exist in their thinking, but unfortunately it does.


    1. Maybe but then no one would read the article.
      The incentives in NZ are all in the wrong places. It’s reminiscent of AT telling concert-goers to drive so that they don’t have to bother sorting out their buses. I’ve seen staff here not that keen to get central govt funding for projects because then they’ll have to do more work (which they don’t have capacity to do). Which is a legitimate worry but they should be able to trust their HR to just hire/contract more people when required.


      1. I regard an TLDR as an extremely brief executive summary. Problem with placement at the bottom is that only those who have read the article will get to see it. At the top, it serves a useful purpose.

        Liked by 1 person

  2. If increasing public transport use is our goal (and I think it should be), then we should be focussing our energy into making our good bus routes great, not our terrible bus routes mediocre.

    We can do both & we need to. PT is first and foremost a public transport service to those that dont have alternative means of transport. Something that was almost completely forgotten in NZ, e.g. PTOM.

    By adding full coverage on-demand services feeding high frequency core services with bus priority we can get both coverage and frequency.


    1. In terms of advocacy I think it’s good to keep pressing for both. But when we do get into situations where we need to make choices with funding (eg LTP’s) I think it’s important to be crystal clear which outcomes each investment will contribute to, and which ones they won’t.


  3. The recent problem with the bus exchange highlights that this expensive, over blown facility is part of the problem. It is extremely slow in and out it has locked in a certain type of bus (yes it will take double deckers) but not all door loading. The temporary bus exchange in Lichfield Street after the earthquakes worked beautifully and is the type that most cities use overseas. The Square in the old days was this type too. But no they had to spend $50m rather that $5m and put the rest to better bus services (eg. stops). Christchurch was making good strides before the quakes but have dropped the ball since then and the figures prove it. Unfortunately a certain Minister took no notice of the brilliant Share an Idea scheme which had public transport at its core and the result is what we have got today. Rant over!


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