Setting Of Speed Limits - Consultation

[Berries]

Thing with CAS is the way the data is collected.

Cops who attend crashes have a variety of pressures which adversely effect the quality of the information which makes its way into the database.

Yet people drawing information out of CAS seem to think it accurately reflects the crashes that have been reported.

More than happy to cut the guys on site some slack. Problem is when they say a crash is serious and describe the injuries which are clearly serious and it gets recorded as minor you would think that NZTA would want to correct the data when told. Nope. Took this to director level at MOT and NZTA and none of them give a shit. At least 30% of serious injury crashes were incorrect in some areas.

I cared for a while as it was my job. Now it isn't I am less bothered.

[rastuscat]

More than happy to cut the guys on site some slack. Problem is when they say a crash is serious and describe the injuries which are clearly serious and it gets recorded as minor you would think that NZTA would want to correct the data when told. Nope. Took this to director level at MOT and NZTA and none of them give a shit. At least 30% of serious injury crashes were incorrect in some areas.

That's the thing. CAS is really valuable, as long as anyone using the data is cognisant of the pitfalls of the data collection.

I've done hundreds if not thousands of crash reports, having started at ACC Traffic before the 5 page crash report was a thing. I know how the way data is collected influences the analysis. Even the mindset of the data collector influences the resulting assumptions.

The key is for whoever is taking the data to realise that it has drawbacks.

[rastuscat]

This is the crux for me. Nothing to focus on = boredom = mind wanders = not paying attention = increased risk. Not able to overtake = frustration = more risky behaviour.

Just magically reducing the speed doesn't fix this, but it does reduce the kinetic energy in a crash. However, this argument has flaws. Why don't you make it even slower (note, I absolutely don't want this)

That's the balance that we need to accept as a society. Efficiency v Safety. I guess the problem is human error, which few of us think we will commit.

Obviously the economic effect of everyone going 30 kmh everywhere would be too great. Even if it meant a 90% reduction in death and serious injury, which it likely would.

So we need to settle on the amount of trauma we are prepared to tolerate in return for increased mobility. The balance has swung between the last government and the current one, which is why this issue arose.

We hear of those who want to be allowed to go everywhere at whatever speed they want, because they are awesome drivers. Okay, so if the population as a whole can prove they are awesome drivers, maybe that would work.

But are we all awesome drivers? Given the number of deaths and serious injuries we collectively cause and suffer, it seems unlikely. But we are all human.

The human trait of optimism bias causes us all to believe that we won't crash. So we believe that the speed we travel at shouldn't be limited, as we aren't going to crash. Which rather flies in the face of the evidence.

Because crashes happen every day to people who didn't think they would.

[Berries]

And then you get this rubbish -

temporary-speed-reduction-after-spate-highway-crashes

A lower speed limit for the next six weeks for a weather related temporary issue. I can almost guarantee there will be a few signs thrown up and no positive traffic management to force a speed reduction yet due to the media reaction over a couple of crashes the Police will have to be out there pinging people for speeding.

Obviously they won't be out when it is foggy as you can't see shit or when it is icy because the risk is too high so the likelihood is they will be there when the fog has lifted, the ice has gone and there is no reason not to be able to do the national speed limit. Anybody would think that the technology is not available to have a sign turn on when the temperature drops to a certain level. Oh hang on, they already use them.

This knee jerk reaction then gets shafted by the fire brigade saying 50-60km/h is a safe speed when it is icy, apparently even when it is so icy you can't even stand up on the road. Top advice that.

[rastuscat]

This knee jerk reaction then gets shafted by the fire brigade saying 50-60km/h is a safe speed when it is icy, apparently even when it is so icy you can't even stand up on the road. Top advice that.

I work at a local council these days, where people expect us to grit every frozen spot, so they can continue to do 1000 kmh wherever they want.

Despite the fact that grit only adds about 10% to the coefficient of friction of any slippery road, so doesn't really solve the problem, it only partially mitigates the risk. Then presents a risk to motorcyclists, well after the ice has gone.

Oh, I'm sorry, it's not safe to do 1000 kmh everywhere.

[Berries]

Fucking hell. 50km/h for 28km of rural road for six weeks because three people failed to drive to the conditions during a cold spell.

Overkill much?

[rastuscat]

Just in case you hadn't see it.

Simeon insists on making decisions based on evidence. Here it is.

[Berries]

No shit Sherlock - concern-motorists-may-ignore-changed-speed-limits

Anyway, should also mention in relation to post #31 that another example of the poor crash data quality is the number of actual SH crashes now being classed as local road crashes. Any data like that shown above which shows a reduction in the rate of SH crashes should take this into account yet it is an issue that has been pretty much kept quiet. I would take any crash stats that are used to try and prove a point with a pinch of salt. it is pretty bloody easy to use the same data to prove the opposite view.

[SaferRides]

Just in case you hadn't see it.

Simeon insists on making decisions based on evidence. Here it is.

I'm sure there is some dubious data shown there. For those of us old enough to remember, the SH2 90 limit was introduced in connection with realignment of the most dangerous section of the road. Someone correct me if I'm wrong, but if there was a period after the road realignment before the 90 limit on the remaining road, it was not very long. It won't be the only example in that figure.

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[rastuscat]

I'm sure there is some dubious data shown there. For those of us old enough to remember, the SH2 90 limit was introduced in connection with realignment of the most dangerous section of the road. Someone correct me if I'm wrong, but if there was a period after the road realignment before the 90 limit on the remaining road, it was not very long. It won't be the only example in that figure.

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I drive through Weka Pass 8 times a week. It was 100 kmh before the 2016 Kaikoura Earthquake, and reduced to 80 kmh a short time after the Eq.

In the 7 years before the speed reduction on 1 July 2017 there were 35 crashes categorised as death or serious injury crashes.

In the 7 years since 1 July 2017, there have been 17.

Little else changed, just the speed limit. Have we all suddenly become better drivers? I think not.

And yet lots of people I speak to maintain that it should go back to 100 kmh, as they were perfectly safe at that speed.

See, nobody thinks they will crash, until they do. But then it's too late.

[R650R]

I drive through Weka Pass 8 times a week. It was 100 kmh before the 2016 Kaikoura Earthquake, and reduced to 80 kmh a short time after the Eq.

In the 7 years before the speed reduction on 1 July 2017 there were 35 crashes categorised as death or serious injury crashes.

In the 7 years since 1 July 2017, there have been 17.

Little else changed, just the speed limit. Have we all suddenly become better drivers? I think not.

And yet lots of people I speak to maintain that it should go back to 100 kmh, as they were perfectly safe at that speed.

See, nobody thinks they will crash, until they do. But then it's too late.

It would be interesting to see these crash rates referenced against other routes unchanged. For example I know avoid some 80k routes for my recreational rides cause 80 sucks. Now how many other people are perhaps doing same? Even say a 10% drop in usage would reduce crash rates because the other party has to be there in right place at wrong time. A bit like how congestion can reduce crashes purely because you can’t pull out to pass to start with.

Let’s not forget two years of crippling lockdowns on travel, reduced migration and tourism activity, reduced economic activity and older less safe vehicles slowly leaving the fleet.

[onearmedbandit]

This I agree with. I know of quite a number of riders who no longer ride to Akaroa, there will be plenty more I don't know of. This alone will count towards a reduction in crashes. Oh well net result is the same.

[rastuscat]

It would be interesting to see these crash rates referenced against other routes unchanged. For example I know avoid some 80k routes for my recreational rides cause 80 sucks. Now how many other people are perhaps doing same? Even say a 10% drop in usage would reduce crash rates because the other party has to be there in right place at wrong time. A bit like how congestion can reduce crashes purely because you can’t pull out to pass to start with.

Let’s not forget two years of crippling lockdowns on travel, reduced migration and tourism activity, reduced economic activity and older less safe vehicles slowly leaving the fleet.

The speed reduction in Weka Pass on 1/7/17 was a direct result of SH1 being closed in late 2016 on the Kaikoura coast, and SH7 becoming the main road North. Traffic basically quadrupled. Crashes started to climb, quite a few as a result of overtaking manoeuvres arising from slower vehicles holding traffic up.

So to say that the decreased crashes were as a result of people not wanting to suffer the lower limit is a bit of a stretch. Covid didn't start until March 2020, and traffic went back to normal maybe 18 months to 2 years later.

Avoiding routes with lower limits is called displacement. It happens. But it's overall effect is marginal. If people want to go to Akaroa, they will go to Akaroa.

But if people want the roads to be a recreational space, they may be displaced by lower speed limits.

[SaferRides]

So how have traffic volumes and speeds changed over the periods before and after the limit was reduced, if the data exists?

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[Berries]

So how have traffic volumes and speeds changed over the periods before and after the limit was reduced, if the data exists?

You could interpret it as crashes going up due to significant increases in unfamiliar traffic and then back to the way it was when SH1 reopened again 18 months later? I would check but have lost access to the database.

After the earthquake I had to do a driveover of the alternative route to SH1 to identify pinch points and potential safety issues, and there were shitloads. Am amazed a truck was not lost over the side in some spots. The problem was doing any kind of improvements was limited by the need to keep the road open. With the need to make sure crashes did not go through the roof NZTA went with the only option they had which was to lower the speed limit. Here it was the only quick fix given traffic was already causing issues but as in many other areas, and i am guessing here, once whatever problem was fixed they never came back to put the speed limit back to what it was.

But if people want the roads to be a recreational space, they may be displaced by lower speed limits.

The road is a recreational space for motorcyclists isn't it, unless commuting?