What defines a busy bus route?

Public transport use across New Zealand, and around the world, is still recovering from the effects of the Covid pandemic. In Tāmaki Makarau, Auckland Transport says use of public transport is back to around 90% of pre-pandemic levels, which is good news. Given the current on-going issues faced by trains (related to the rail network rebuild) and ferries (due to a shortage of crew), it is buses that have been leading this charge in our biggest city.

In Auckland, around 40% of boardings (across all modes) are during the peak hours (7am to 9am and 4pm to 6pm), while the other 60% is during the rest of the day. So, while many people may experience the return of patronage as a full bus as part of their morning commute, services are also busy throughout the day and into the evening. This is something that many peak time commuters don’t often see. If most use is outside peak times, how can we really judge what a well-used bus route is? 

This is the first in a series of posts looking at how we can fairly judge what exactly a busy bus route is, what the busiest routes are in Auckland, and how those compare to others across Aotearoa. 

How do you fairly compare routes?

There are many possible ways to measure how busy a bus route is, most of which focus on the performance of individual trips (such as utilisation of on-board capacity). These metrics are valid, but they tend to focus on or favour measurement of the peak period. If we want to measure the overall performance of the route, then we need a different measure.

Measuring overall boardings on a route is an obvious approach, but it has its flaws too. Bus routes have different lengths, frequencies, sizes of vehicles, and other characteristics that mean just looking at boardings doesn’t give a complete picture. A hypothetical route that runs infrequently but has all its seats taken may have the same number of boardings as a service that runs every 5 minutes but is only a third full each trip. Which of these would we say is busier? We need a way to fairly compare these routes.

One measure that allows for a fair comparison of routes with different frequencies, lengths and runtimes is boardings per service hour (BPSH). This measure is based on the idea that a ‘service hour’ is essentially a standardised unit. One hour’s worth of service on a busy route costs essentially the same as an hour on a quiet route, given driver wages are the main cost of operating public transport (and the size of the bus doesn’t have a significant impact). The metric therefore allows us to look not just at how busy a route is, but how efficient it is.

To understand this metric, consider this example, if Bus Route A runs hourly, and its trip takes 30 minutes, that is half an in-service hour. Bus Route B’s trip also takes 30 minutes, but ran every 15 minutes, that would be two in-service hours’ worth of time. If there were 10 passengers using each service within those same hours, that would equal 20 (10/0.5) and 5 (10/2) BPSH respectively.

Using this metric, we can look at how busy routes are relative to each other (even if they operate differently). We should also keep in mind that not every route is designed to achieve high BPSH – some routes play an important coverage role, providing transport access to areas that may never be expected to have many boardings. In Auckland, most services are expected to achieve at least 17 BPSH, with most others between 7 and 17.

What are the busiest routes in Auckland?

Auckland Transport helpfully reports its BPSH figures by route on its website. I used data from March 2023 to compare it with publicly available data from other cities.

The core routes of the Northern Busway, the NX1 and NX2, are the busiest in Auckland, perhaps unsurprisingly given they are premium, rapid transit services. The NX1 achieves between 60 and 80 BPSH, while the NX2 manages around 50 to 60.

The Dominion Road peak bus services (252, 253) are the next highest, with around 50 to 60 BPSH each. These services only operate at peak times (in the peak direction only), so it is also unsurprising that they perform well. The all-day Dominion Road services (25B, 25L) manage around 30 to 40 BPSH.

Rounding out the top five is route 70, from Botany to Britomart. This is the highest non-rapid transit all-day route, and it achieves between 40 to 60 BPSH (depending on the month). Given the route’s length and travel time are longer than the other already mentioned routes, this is a strong performance.

Most frequent routes (including where services are made up of two branching routes, like the 22N and 22R on New North Road) average around 25 to 35 BPSH. Generally, BPSH is highest for frequent services, then connector services, then local services (using the terminology from AT’s service hierarchy) and AT’s targets for these services are generally in line with this expectation, with a few exceptions where connector routes perform especially well.

What about examples of low performing routes in Auckland?

The lowest ‘regular’ all-day service that AT operates is route 393, the Pukekohe South loop, which manages around 4 to 5 BPSH. This service has a low performance given it operates in a smaller rural centre, and also suffers from the fact that Pukekohe’s train station is currently closed.

Many other low performing routes are rural services (such as route 128 between Helensville and Hibiscus Coast), or services to developing areas (like route 378 between Karaka and Papakura).

The lowest performing all-day service within the central Auckland urban area is route 783, the Eastern Bays Loop. This service manages around 6 BPSH. It connects to a number of smaller centres, like Eastridge, Mission Bay, Kohimarama and St Heliers, and provides connections to services like the TāmakiLink. The route is essentially a ‘coverage’ service, designed to plug gaps in the wider network and ensure connections are available all-day to these centres from places like Glendowie. It is also a wealthier area, relatively close to the city centre, which is likely to impact on the use of services.

How do Auckland’s BPSH compare to other cities in Aotearoa?

No other New Zealand region publishes information about boardings per service hour, and many only release network-level information. A few regions do release route-level boardings information, which makes it possible to work out BPSH by calculating the number of in-service hours (from timetables) and then dividing the boardings by these.

Importantly, Auckland’s reported BPSH is based on weekdays only. Where other cities publish their route-level boardings, it is usually by week or month, so calculating BPSH involves considering weekends. This gives Auckland’s figures a slightly unfair advantage, as Auckland’s weekend patronage is usually roughly a third of weekday patronage while services generally operate at a similar level of all-day frequency on weekends (in all cities). The data used here is all taken from March 2023, so may be slightly out of date given the rate at which public transport use is returning.

Wellington’s three busiest routes (in terms of total boardings per week) perform well in terms of BPSH compared to many of Auckland’s strategic routes:

• Route 1 between Island Bay, the City Centre and northern suburbs achieves around 30 BPSH.
• Route 2 between Karori, the City Centre, and Seatoun achieves around 35 to 40 BPSH.
• Route 14 between Kilburnie, Roseneath, the City Centre, Wilton and Karori achieves around 30 to 35 BPSH.
• All of these routes benefit from being ‘pendulum’ routes that are routed through rather than terminating within the City Centre. This means each trip can achieve high utilisation and boardings in both directions.

Christchurch’s three busiest routes are slightly less busy than Wellington’s but still perform well compared to many of Auckland’s strategic routes. Use of public transport in the city is still relatively low compared to what it was before the 2010/11 earthquakes, due to network changes and businesses moving away from the city centre to areas where the public transport network is less competitive with other modes.

• Route 3, between the Airport and Sumner, achieves around 28 BPSH.
• Similarly, route 5 between Hornby (with some services starting in Rolleston) and New Brighton also achieves 28 BPSH.
• The suburban circular Orbiter route is the next-busiest route and achieves 16 BPSH. The reason this is lower than the other routes is partly due to its high (10-minute) frequency throughout the day.

As a smaller centre, Tauranga’s performance is unsurprisingly lower. Its three busiest routes, in terms of monthly boardings, are closer to the performance of ‘local’ routes in Auckland (despite some running every 15 minutes, which is considered ‘frequent’ in Auckland):

• Route 2B between eastern Papamoa, Bayfair and the City Centre achieves around 6 to 7 BPSH.
• Route 5 between Bayfair, Mt Maunganui and the City Centre achieves around 9 to 12 BPSH. This is the highest performing route, given it connects three key centres.
• Route 55 between Ohauiti, Greerton and the City Centre achieves around 9 BPSH.
• Despite all these routes serving multiple centres at decent frequencies, Tauranga’s lack of bus priority and relatively uncompetitive travel times (even with the traffic congestion the city experiences) likely contributes to relatively low BPSH. As noted above, these services may perform better if considering just weekdays.

So what?

Consideration of BPSH provides a useful way to compare how well services with different characteristics, in different jurisdictions, are performing. As a standardised measure, it lets us check if services that have fewer overall boardings are performing well against more popular routes by considering the amount of resource required to operate them.

BPSH also provides a useful way of checking if a potential improvement to a route is worth the investment. Hypothetically, a large percentage increase in boardings may make an improvement sound appealing. If achieving that increase requires investment that will reduce overall BPSH, however, we might think that it is not actually efficient. Ideally, we should be increasing both overall boardings and BPSH, to ensure the best value for money.

In closing

A ‘busy’ bus service in New Zealand’s three main centres appears to be one that achieves over 25 boardings per in-service hour. This accounts for the busiest routes in Christchurch and Wellington, and the top 25% of all routes in Auckland.

Not all routes are meant to carry lots of people all the time. Public transport has an important social role in providing access to transport for everyone in the city (especially those on lower incomes or who may not be able to use other forms of transport).

In the next post in this series I will look at the factors that contribute to routes achieving high BPSH, and compare New Zealand cities performance to cities overseas.