How good is the interim NW busway?

This is a guest post by Pshem Kowalczyk, a long-time follower of the blog.

With great fanfare, just over six months ago (on 12 November 2023), AT launched its interim busway for the NorthWest region, with the new WX express service at the heart of the changes. I live in Te Atatū Peninsula, so these changes have impacted me directly. I realised I tend to catch the bus much more often these days, although I still predominantly commute on my e-bike.

The NW interim busway solution comprises a number of key routes:

• WX1 – between city centre and NorthWest shopping centre, travelling along the motorway between Newton Rd and Hobsonville Rd
• 13 – between Henderson train station and Te Atatu Peninsula
• 11T/W – between city centre and NorthWet shopping centre, travelling along Great North Road, the motorway between Pt Chev and Lincoln Road and Waiumu Rd (11W) and Triangle Road (11T)

A number of other routes that intersect with the busway services were also either updated or created.

The “busway” as such is made up of a number of stretches of bus shoulders (mostly between Pt Chevalier and Westgate), but it lacks continuity across the motorway interchanges, and critically – there’s almost no bus priority between Pt Chevalier and Newton Rd.

[Editor’s note: over the last decade and a bit, despite massive investment spent widening SH16, NZTA egregiously and repeatedly threw NW public transport under the bus instead of building a proper facility akin to the Northern Busway, This ranks right up there as one of the most regrettable planning failures for Auckland.]

Auckland Transport provides a GTFS (General Transit Feed Specification) API, which allows for querying things like real-time departures or bus occupancy. So, I decided to tap into that feed and started collecting information about bus movements in order to figure out how well the interim busway system is performing.

It’s important to acknowledge that the analysis that I’ve done has some limitations:

• Some bus runs are not being tracked at all, hence their performance is not reflected here
• Occasionally I saw “glitches” – buses disappearing from the system (perhaps due to a bus failure or other incident)
• AT’s system doesn’t store “historic” data, so once the bus run is finished the data disappears, if my system didn’t manage to query the data in time – it also would be lost.

And a note: you can click on any of the graphs below to open them at full size in a new tab.

Journey times: how long does it take?

The first thing I looked at is how long it takes for the buses to travel between various bus stops. I used the data from February and May (workdays only). The graph below shows the WX1 travel times between NorthWest (Stop 5959, Kedgley Road/Maki Street) and Karangahape Road (Stop 7135, Rainbow Bridge/Karangahape Rd).

The main takeaway here is that the actual travel times vary a lot throughout the day as a result of congestion and are on average 10-12 minutes shorter than the timetable suggests, even at peak. Also between February and May, travel times improved a bit.

In the westbound direction, between Karangahape Road (Stop 7136, Rainbow Bridge/Karangahape Rd) and NorthWest (stop 5941, NorthWest Shopping Centre) the WX1 travel times look like this:You can see clearly here that westbound services get caught up in traffic congestion: it takes 50% longer for the run during the afternoon peak than during inter-peak. In this case as well, the timetable is more pessimistic than the actual run times. The travel time in that direction is getting worse over time, too, as we can see in the graph below which shows median travel time by week (during the afternoon peak):

For comparison, here’s the travel time for the NX1 service between Albany and Victoria Park (the data covers the same days as for WX1 above):

Even though the outbound travel times are not exactly flat, the variation is fairly small – the NX1 only takes about 4 minutes longer at peak than at other times. What’s interesting here is that the timetable is definitely more optimistic than the actual travel times.

Reliability: how close to the advertised timetable?

As a user of the bus system, I also want to know how likely it is that my bus will be at the bus stop at the advertised time. So I looked at a number of bus stops and routes to see how well they actually perform. The key routes run with the following nominal frequencies:

• WX1 – every 10 minutes, peak and interpeak
• 13 – every 7-8 minutes at peak, 10 minutes interpeak

In theory, these frequencies should allow for a “turn up and go” type of service.

First, let’s have a look at the most frequent route – the 13. I checked the time between buses for two of the stops: 5102 – Roberts Road in Te Atatū South and 5080 – Abbotleigh Avenue Te Atatū Peninsula (data collected for workdays in May):

These two graphs show the distribution of the amount of time between buses, i.e. the waiting time for a person at the bus stop. A few things can be seen here:

• In about 75% cases (the big rectangle in the middle of each column plus the bottom “whisker”) the wait time is quite close to or even less than the advertised timetable
• The reliability visibly drops at the later stop (Abbotleigh Ave)
• The buses tend to bunch up at peak time (note how the bottom “whisker” reaches 0 minutes between buses)
• There can be about 20 minutes between buses in the worst case scenario

But all of that means that overall the service is actually quite good.

Let’s now look at the flagship service: the WX1, at Te Atatū Interchange stop A (towards the city centre) and at the Rainbow Bridge on Karangahape Road (towards NorthWest):

The graphs above show that 75% of buses show up around the advertised time or earlier, with half of them arriving within a few minutes of the schedule. The afternoon (17:00, 18:00) buses from Te Atatū Interchange towards the city centre seem to be the most unreliable, perhaps as a result of the outbound services being delayed. There’s some bunching up happening throughout the day as well.

But again, this service actually looks quite good.

Here, I couldn’t resist comparing the frequency and reliability of the WX1 at Te Atatū with the NX1 at Akoranga.

This comparison does show that the WX1 has some way to go before it achieves the frequency and arrival time reliability of the NX1. The graph shows that in the worst case scenario the wait time for an NX1 bus is never much longer than 10mins, whilst for the WX1 it’s easily over 20 mins.

Occupancy: how busy are the buses?

The next thing I decided to check was bus occupancy: how full are the western express buses? AT reports occupancy as a single number, from 0 (the bus is empty) to 5 (the bus is too full to pick up passengers).

I checked what occupancy looks like for the WX1 at Te Atatu Interchange stop A (citybound) and at the Rainbow Bridge on Karangahape Road (Northwest-bound).

If these numbers are to be trusted, it seems the likelihood of being left behind, even at peak, is not huge. I’d be interested to hear of people’s experiences with this.

Over the period the WX1 has already been operating, the mean occupancy looks quite stable. This graph shows morning peak for the citybound service at Te Atatū Interchange:

Where are the congestion pinch-points?

Finally, I checked where the biggest pinch points are, by comparing travel times between stops during peak time (7am-9am or 4pm-6pm) with the inter-peak times (10am-2pm).

The graphs below show how much longer the travel is likely to be at peak, with the especially bad (or unreliable) stretches highlighted. What I found quite striking here is how long can it take for the WX1 to simply get from Lower Albert Street to Victoria Street West in the afternoon peak.

AT has recently made some improvements to Te Atatū Rd, and from mid-May the T2 lane in Te Atatū South became operational, making it easier for the Route 13 buses to travel along Te Atatū Road. The graph below shows the travel time between Henderson Station and Te Atatū Interchange in May, before and after the T2 lane became operational.

As you can see, the new bus lane saves about 3 minutes on each bus run.

Another thing I wanted to verify was the claim at the Te Atatū Interchange that the citybound 11T/W takes about 5 minutes longer in peak than the WX1.

Which turns out to be true: and off-peak, the difference is closer to about 8 minutes.

Finally, I decided to settle a long outstanding question – which day of the week is the worst when it comes to travelling from the NorthWest to the city. This graph is based on all the workday data from the beginning of the year, and shows the morning peak travel time from the Northwest to the city.

It’s clear that for travel time, both Wednesday and its close runner-up Thursday are not great (or conversely great days to take the e-bike instead, if you can):

As for the return journey in the evening peak, city-to-NorthWest: Thursday just edges out Tuesday and Wednesday as the longest bus ride home of the week.

Interestingly, Friday comes out best in both directions, with Monday second-best. What’s that about?

To summarise my analysis – and to answer the question in the title – quite good, actually! The interim busway seems to be performing reasonably well, despite the fact that buses regularly get caught up in traffic. The high frequency and relatively good reliability make this service a great addition to the network. Let’s hope more priority measures can make the services even better.

Share this