That said, it's hard to see the point of sending people there. We'd probably get a lot more exploration done with the same money spent on more rovers.
The Boeing 787 cost $30 billion to develop, and it gets you to California. Subsonically
Sure, but that's quite a different thing. Flying millions of people around the world safely has quite different economics to sending a couple of crazy buggers on one mission.
To be fair to the modellers, it's a very difficult job. But what Richard said has to be the case, that really the uncertainty in these models could be huge, and does not seem to be included.
They have to use some kind of model, just to claim being evidence based, but that doesn't mean that even on our best analysis we can really claim much surety about what the future holds for that intersection under any of the proposals, especially not in light of the huge change to the motorway network nearby.
Given how short the extra lane replacing the tress is in the plans, looks like about another 7 vehicles will sit there between light changes, waiting to sit on the wider motorway overbridge before either continuing to St Lukes or turning onto the motorway westbound. Doesn't seem like much of an overall gain.
It is possible that they will phase the lights going onto the motorway to favour the increased flow capacity that the widening would create, at peak times. But I think you're right, the real bottleneck is actually the on-ramp intersection itself. That's always been how I've experienced it. Even if it's two lanes wide, the fact that it's got lights stopping it half the time means its real flow is only that of one lane anyway. One lane is quite sufficient to fill the bridge completely between phases. There is also the on-ramp flow control lights which carefully meter the flow onto the motorway - at busy times, the flow further back can't really exceed this. It will, in fact, be less, because there is traffic coming down St Lukes Rd and turning onto the motorway there, which is unimpeded by any signals and directly competes for those lanes.
Already, if I have to drive south of Auckland, I’ll generally take the Manukau route – it makes much more sense than driving into town to pile on the southern motorway.
But unless you use St Lukes, the tunnel doesn't actually make your own route have more motorway - you'll still be driving to Maoiro. Nor mine, despite living close west of the tunnel. I'll still have to drive to Maioro Rd. What I won't have to do is contend with people who would otherwise have turned off at Patiki, Pt Chev, or St Lukes, to get to south. So it's quite a big improvement really. And now I do have the option of doubling back to Patiki and using the tunnel, if it really is a lot faster, although time will tell on that.
I wonder (drunkenly) if such apps are statistically significant. Is an entire day's lag even going to show up in traffic flow, with hundreds of thousands of people making choices? By the time tomorrow rolls around even people who don't have smartphones know which way sucks more.
Yet traffic engineers prefer to pretend this common ‘induced demand’ does not exist when they do their modelling to justify moar roads.
I credit even knowing about the idea to a traffic engineer. Her Masters thesis was on "Pedestrian Crossings For the Disabled" so we're not talking about some Randroid here. It was like the Market Efficiency Theory of traffic, the kind of thing they all know about, but only the right wingers actually believe with enough lust to base decisions on. And if it wasn't true, they'd have invented it anyway.
I expect they will have on-ramp flow control lights to deal with exactly this. It’s quite possible for the new flow from the tunnel during rush hour to be throttled back so that it doesn’t jam up SH16 (although it either has to slow SH16 down, or they have to throttle the SH16 on-ramps).
It is never going to be a no-brainer to use one route over another, because people compete to use resources. For the most part, similar routes tend to balance in the time they take, for the simple reason that people will choose the shortest route. So if the number of commuters remains the same, the tunnel will be a preferred choice for just enough people that it’s actually quicker for. The rest will use the existing routes, and be competing initially with fewer motorists. If commute times drop significantly, they’re often just hoovered back up by people making choices to commute rather than not, but that does take a lot longer to happen. In the meantime, added capacity can only be an overall good.
Some areas might actually get more choked, but we do have a very simple technology to adjust this, the taps on the motorway on-ramps.
ETA: Just checking, it looks like all the SH20 on-ramps already have those lights.
Sure, but I've often had to wait 3 phases to get around the corner at Western Springs, coming from the west, and once you get onto the on-ramp you have flow-control lights that can take several minutes to get through. Then you contend at any time approaching rush hour with the motorway only going at a slow pace anyway. So I guess we'll see.
the kind of progressive chap who would give all due acknowledgement to the Ladies’ Rugby Auxiliary, even if they’re not currently winning.
Naturally. There's no losers when every lady provides a plate!
I guess we'll end up seeing. If St Lukes bridge chokes, then 2 minutes to drive 1.5 km through 3 sets of lights to Western Springs, get over the bridge (2 sets of lights) and then through the on-ramp lights and then drive back 1.5 km in heavy traffic to pass within 50m of where you started might seem optimistic.
The other route has 7 sets of lights. I'd think that if 2 cars left simultaneously on the alternate routes, then by the time the motorway seeker was actually on the motorway by St Lukes Rd, the other car would have already crossed New North Rd. Then it's a race for the motorway car to cross 5km in the time it takes the other car to go 2km along Richardson, Stoddard and Maioro.
Will be interesting to see if there's much time saving for the extra 3 km (which also cost more in petrol or road-user charges).