How Far in Half an Hour?

For those who don’t know, public transport in Christchurch is in a bad way. And I spend an unhealthy amount of time thinking about how to fix it. Pre-earthquake Christchurch enjoyed a successful bus system, with reasonably high public transport patronage which was growing every year. Then in 2011 the earthquakes happened and that all changed. The city centre emptied out. Activity dispersed. Patronage plummeted. Various changes have been made to try and fix it. But we’re now seven years on and public transport patronage in Christchurch is still floundering.

To get my fix, I decided to do some analysis on accessibility to the city centre by public transport. Most cities in the world do something like this, but I’ve never seen it done for Christchurch. This website here (www.mapnificent.net) has some nice interactive maps showing how much of the city can get to the CBD by public transport within various times. But Christchurch hasn’t been mapped. ATAP included something along similar lines for Auckland, although far more comprehensively. This paper here (https://marroninstitute.nyu.edu/uploads/content/Cities_as_Labor_Markets.pdf) explains why connecting residents to jobs is a good thing, and this one https://smartgrowthamerica.org/resources/measuring-access-to-opportunity/) goes into more detail about how best to try and measure this.

I took inspiration from these sources, but because I was doing it in my spare time I had to simplify things. I downloaded the open source software QGIS and freely available bus and street information.

I mapped out how much of the city is within a half hour bus and walk trip of the city centre (using the central city bus change as the centre point). A few disclaimers:

  • I only used the high-frequency bus network
  • I based speeds on the timetabled speeds during the AM peak period (arriving at the bus exchange at 8:30am on a weekday).
  • I included a wait time of half the peak period headway (which is 15 minutes on most routes).
  • Likewise I included a transfer wait time of half the peak period headway.
  • I used a commute time of 30 minutes as the cut-off, as this seems to be commonly used internationally.
  • Population data was taken from the 2013 census (this showed 344,000 people living in Christchurch, excluding satellite towns like Rolleston and Rangiora).

Firstly, the map below shows in green how much of the city could get to the CBD in half an hour if there were no buses at all, just walking. The fuzzy grey dots denote population density, the black lines are the high frequency bus routes.

Walking.png

Roughly 23,000 residents (7% of the population) live within this green blob and can walk to the CBD in half an hour.

Secondly, the map below shows in blue how much of the city could get to the CBD in half an hour with the current bus network.

Buses_Now.png

A much larger 106,000 residents (31% of the population) live within this blue blob and can get to the CBD in half an hour by walking and bussing.

Thirdly, I thought I’d see what happened if we put in more bus lanes and bus priority. This increases the bus speeds in congested parts of the network. To simulate this I just increased the routes with the lowest bus speeds (15-20km/h), up to a fairly modest 20km/h average speed (based on timetabled speeds of buses on bus lanes in Wellington and Auckland).

Buses_Priority.png

If we did this a slightly higher 119,000 houses (34% of the population) could get to the CBD in half an hour. It has less impact than I was expecting, mainly because the average speed of 20km/h I used is only slightly faster than what the buses are going at currently.

Fourthly, I thought I’d see what happened if we doubled frequencies on all routes. This halves the waiting and transfer times.Buses_Frequency.png

If we did this, an additional 41,000 houses could get to the CBD in half an hour, bringing the total to 147,000 (43%).

Fifthly, the map below shows the results if we both put in more bus lanes/priority and doubled frequencies.

Buses_Both.png

If we both put in better bus priority and doubled frequencies across the core bus network, then 163,000 (47% of the population) could get to the CBD in half an hour.

Two things stand out to me about these results:

  1. Contrary to what you often hear in the media, a lot of Christchurch is actually not too badly serviced by public transport, with about a third of the population currently able to get into the CBD in half an hour or less, including walking and waiting time. But this is offset by large swathes of Christchurch that are poorly serviced by public transport.
  2. With investment solely in our existing bus network we could get around 163,000 people within a half hour commute of the CBD by bus (a 50% increase on the current 106,000). This would have huge benefits in terms of maximising the city’s labour pool, and would massively boost the usefulness of the bus network in Christchurch for all sorts of non-commuting trips too.

To me it’s encouraging that investing in increasing frequencies and speeds of buses would make a significant different to the number of people able to catch the bus into Christchurch CBD in a reasonable timeframe.

Next post – how would trains change this picture?

Feel free to comment below – I’d be interested to hear anyone’s thoughts on what you would do to fix the Christchurch bus system if you had the chance?

16 thoughts on “How Far in Half an Hour?

  1. When I moved to Christchurch in 2015, I was frustrated over how many services such as public libraries & swimming pools were not served well by public transport – even given the rebuild. The whole city seems laid out for cars. Many pedestrian signals flash on the walk signal so briefly, it feels like you’re being penalised for not being in a car. The best way to get around is by bike & even some of those bike signals favour car traffic even when there is none.

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    1. Yep I agree. I think prioritising driving over other modes has been done far too much in the past few decades. We have a long way to go to giving public transport the priority it needs to operate well. And you’re right- despite making a lot of progress with prioritising cycling there are still heaps of places where signals and intersections make it harder than it should be to bike.

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    2. I agree, the walking priority through out the city seems a second thought.
      If you look at the recent Madras street upgrade , the city has added three signalized intersections which we possibly could of placed zebra crossings due to the low traffic numbers.
      I could go on about pedestrian priority at intersections though…

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      1. Do you mean Manchester St, Tim (with the bus priority corridor)? Madras is a busy one-way arterial, so it definitely needs signals. Manchester St, hmm, could almost get away with zebras, although still need to factor in maintaining the bus priority routing along the corridor. And Manchester will certainly get a lot busier with pedestrians as the adjacent housing developments get built.

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      2. Please do go on! I actually haven’t been down Madras St for a while so not sure what’s happened there. I think in the past walking has quite often been pushed into the background. Ive seen a few recent projects that have made an effort to ensure walking is easy, pleasant and safe. But lots more we ought to be doing…

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      3. Yes. Currently on Manchester it is sooo much faster to use the parallel Huanui Lane https://osm.org/go/uoyhNBunt-?m= for walking or biking. Because the crossing points have no lights etc, the law-abiding don’t have to wait nearly as long. Also safer because you’re not dealing with turning traffic.

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  2. Interesting analysis. I suspect if you add in some of the next-tier bus services (i.e. 30-min frequency ones) you would fill in a few more areas, even with a “half headway wait time” of 15 mins. E.g. the no.29 airport bus gets to about Ilam Rd along Memorial Ave in 15 mins of travel, thus helping to fill in that “hole” in the map.

    Perhaps then it’s not surprising that the proposed Regional Public Transport Plan (about to go out for consultation), proposes adding four additional core routes with at least 15-min frequencies, as well as beefing up the frequency of the existing core routes to 10-minute headways. It might be interesting to plot the effect of the proposed network to see what that would do to city coverage…

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    1. Yep I wrote this article a few weeks ago before the new public transport plan came out. Now I’ve seen the proposed future bus network, it’s definitely something I’m keen to insert into this analysis. The report even includes a target that “90% of households can use public transport to access one or more key activity centre within 30 minutes”, so I’d be interested to know what needs to happen to achieve that target.

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  3. Chris I wonder if you could clarify what you mean by journey time into the CBD please. Does this mean destination = Bus Interchange, or actual desired destination. I assume it would be to Interchange. Take my example. Living just out of the green zone, walk time to work ( hospital ) is around 40 minutes. Bike time to work is 15 minutes , sometimes less. Bus journey can range from 37 to 48 minutes depending on route. The 37 minute option involves 23 minutes of walking , the 48 minute option requires a 35 minute walk. If someone cannot walk that far, there is the option to wait for a bus at the Interchange to travel to the hospital, adding more time again to overall journey. On very wet days I have no problem taking the extra time to bus, knowing that it is only one journey in about 20 that can take up to 3 times longer than biking. I think that routing most of the bus routes from the north around to Manchester St rather than having some approach the CBD via the west ( Durham St ) was a mistake. Access to the entire city west side, ( including Hospital ) is severely restricted. If buses do eventually get to use Kilmore rather than Salisbury, that will help. But at present it is either a long walk from Salisbury to the West End , or a long bus journey then another walk.

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    1. Yes that’s correct, journey time is just to the bus interchange. hmmm.. yea I do see what you mean, I always thought bus provision to the hospital must be alright because it has 2 high-frequency routes right past its front door, but I guess if you’re coming from the north it requires either a detour to the interchange and a transfer, or a fairly long walk. It’s important because the hospital is a massive origin/destination for people.

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  4. Hi Chris, any thoughts about how things are likely to change once CNC is complete and far less traffic will be funneled down Main North Road then Papanui Road?

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    1. In the short term less traffic should mean more reliable travel times, although not faster as buses still have to stick to their timetables (initially anyway). In the medium-long term the law of induced traffic means that in time these roads will just fill up with traffic again. If we want to avoid that happening, we need to take the opportunity given by the temporarily low traffic volumes to make changes to these roads (traffic calming, bus lanes, lower speed limits etc).

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