Christchurch’s Riskiest Intersections for Cycling?

Hot on the heels of the recent cycling fatalities in Christchurch, and with the potential for massive new investment in cycleways in Christchurch, The Press has come up with an “interesting” article looking at where the “riskiest” intersections for cycling are around the city.

Blenheim Rd / Hansons Lane – is this Chch’s riskiest intersection for cycling? (c/ Fairfax)

In principle their approach makes sense: first they obtained reported cycle crash data from 1990 to the present day throughout the city. They also obtained cycle count data from Chch City Council for each intersection that was available. By determining the ratio of crashes to cyclists at each site, they were then able to rank different sites in terms of risk. From this, they determined that the top 3 in terms of risk were: Blenheim/Hansons, Papanui/St.Albans, and Harewood/Johns/Russley.

The Press’ interactive graphic map of relative cycling risk

There’s one big methodological flaw with this exercise in terms of its present-day value: it is looking at crash data over 23 years. That is a very long time to use for assessing cycling safety (by comparison, most road safety studies use no more than 5 years, 10 at most). Cycle patterns and traffic patterns will no doubt have changed over that time; particularly in the last two years since the earthquakes. The sites themselves will also have changed; it may be precisely because they had a bad cycle safety record that many might have been upgraded. When I look at the “high/medium risk” sites on the map, about three-quarters have had some kind of cycle-friendly treatment done to them in the past 20 years (e.g. cycle lanes).

Another thing that this assessment won’t show is evidence of risk mitigation or “danger reduction”, where some people may avoid a particular location because they deem it too risky (multi-lane roundabouts are a common example). Because not many people use it, there aren’t many crashes and so it might fly under the radar. And yet, many people might like to go that way if the option was a bit friendlier for them.

The other thing The Press totally misses (again…) is a bit of context. Let’s have a look at the “riskiest” site, Blenheim/Hansons. In 23 years it had 6 cycle crashes (2 severe, 4 minor). Over that same period, from the cycle count data I also have (which only captures peak hour periods, so needs to be scaled up for all-day counts), conservatively at least 300 riders a day have used that intersection (possibly 400-500). 300 a day over 23 years translates into 2.5 million cycling trips. So that’s one cycle crash for every… 400,000+ riders going through the intersection. Even if you allowed for some under-reporting, they still sound like pretty good odds to me.

This is not to say that there aren’t intersections around that couldn’t benefit from some improvement from a cycling perspective. But, by plastering most of page 2 of Saturday’s Press with a big article and graphic about the city’s “riskiest” sites for cycling, the newspaper have probably only succeeded in once more putting a few more people off riding, because of a misperception about the true safety of cycling. As alluded to in an earlier post, even without new cycleways to help us, the truth is very different.

¬†What’s your “riskiest” intersection in the city to ride through?

5 thoughts on “Christchurch’s Riskiest Intersections for Cycling?”

  1. The Press does an excellent job of bad reporting in my opinion …
    But on to the intersections: I find the Sockburn roundabout (multilane) absolute horror. I avoid it like tha plague, but occasionally I see cyclists risk their ife there. The so-called cycle lane, which goes on the curb, isn’t much safer than the road either.

  2. I try and stay on cycle friendly roads but two intersections on Shakespeare Road are very un-friendly. These are Wilsons Road at the bend where it connects to Shakespeare /Opawa Rds – the Stop sign is often treated as a Give Way especially with left turning cars in a hurry. And the cute split for traffic onto Brougham (I hate these splits whatever they are called); free turn left or straight ahead to the lights. This is one piece of road it is better to ride with dense traffic present since it is easier to weave through slowed cars. Cars aiming for the free left turn are often speeding up…

  3. A friend of mine noted: the thing about Blenheim/Hansons is that it’s the alternative route that was put on signage for cyclists when the cycle lane was taken out of Curletts Road (between Main South & Blenheim) after the earthquakes.

  4. I nominate the (double lane) Johns Rd/ Sawyers arms Rd roundabout. Yep I know I should be avoiding this like the plague but I do not really have another option, I have to cross this one or commute by car. Today I had entered the fully empty roundabout and was just about to cross the second lane and a Meadow Fresh SUV coming from the south side accelerates aggressively and missed me by not much. He also made some rude gestures, usually this cheers me up but not today. This roundabout is never going to work for cyclists, time for a tunnel or overpass I would say!

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