An NZ Herald article notes that the Mangere Bridge was formally opened earlier today, by the Minister of Transport. Here’s an extract:
Motorists in Auckland are set to benefit from reduced journey times to and from the airport after the new duplicate Mangere Bridge across Manukau Harbour was officially opened today.
The New Zealand Transport Agency (NZTA) and the Manukau Harbour Crossing Alliance completed construction of the 650 metre-long bridge seven months ahead of schedule.
People were given the chance to walk and cycle the new bridge today before it opens to motorway traffic.
The $230 million project, together with the existing bridge which opened in 1983, increases capacity on the Southwestern Motorway (State Highway 20) to 10 lanes across the Manukau Harbour – with eight lanes for general traffic on the bridges and two shoulder lanes for buses.
Ah well at least the bus lanes mean there might be some benefit for public transport users.
The benefits of the project were trumpeted by NZTA Chief Executive Geoff Dangerfield:
The duplicate bridge is on one of the country’s most important routes, NZTA chief executive Geoff Dangerfield said.
“The additional traffic and bus lanes will reduce congestion, and shorten travel times for commuters, visitors and exporters who depend on travel reliability to get to the airport.
“Time savings of up to 20 minutes are expected for journeys between the CBD and the airport at peak,” he said.
The duplicate bridge has a fourth southbound lane dedicated to local traffic between the communities of Onehunga and Mangere Bridge. The existing bridge beside it will be refurbished to carry four northbound lanes.
I’ve underlined what I think is the most important bit here. NZTA reckon there will be a 20 minute benefit for people travelling between the CBD and the Airport at peak times just because the motorway has been widened by a few lanes? Crikey, if the benefits are that great then one wonders why we’re even bothering with the Waterview Connection. That project is being justified on the basis that it’ll save people 15 minutes off a trip between the Airport and the CBD. Any more motorway projects to speed up this trip and driving sounds like it’ll be about as fast as teleporting from the city out to the airport.
But being serious here, this “20 minute savings claim” make me think very much of a post I did a few weeks back questioning the veracity of these “time savings benefits”. I’ll re-post my concluding paragraph:
What I think we need to measure is the ability of a project to “increase the number of people within “x” minutes of “y” location” (ie. measure the number of people whose accessibility has been enhanced), rather than hope that a particular project will save a certain number of minutes off travel time, and then measure those minutes. We must take into account induced demand: both in terms of triple-convergence, but also in terms of longer-term changes such as whether the project is inducing people to travel further, or whether it’s encouraging land-use patterns that will eat away at the project’s benefits over time. I think it is only then that we’ll be able to truly measure the benefits of our transport investment accurately, and I think such a change could throw up some interesting results.
There may well be an advantage of having a greater number of people within a 30 minute drive of the airport, for example, as a result of this project. But if that’s the case then that’s what we should and must measure. It won’t sound quite as “sexy” as a claim that “this project will save you 20 minutes off a peak time trip”, but it will actually be true.
I fully expect that within a few years the Mangere Bridge will become just as congested as it is now with four lanes. Mark my words, motorway widening has never fixed congestion before so I don’t see any reason why it would start fixing congestion now.
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He left off the end of the comparison ‘compared to when the current bridge was closed for several weekends to enable construction to take place’.
I can’t see this new bridge saving even 20 minutes even on day 1, this doesn’t meant it shouldn’t have been built but it does seem like quite an extreme claim.
Yes you’re right Matt, that doesn’t mean the project shouldn’t have been constructed. It makes sense that if the Mangere Bridge is at capacity now, and you’re trying to encourage more traffic off state highway 1 and onto state highway 20 as part of the Western Ring Route, then you will need to widen that part of the route.
However, I just wish that it was being sold this way. The benefits it will bring to SH1, the benefits of having more people within x minute of the airport and so forth. Just I wish they’d lay off the ultra-optimistic time savings benefits for the route itself.
Just another thought, it would be interesting to ask Joyce how long he thought it would be till traffic was congested again, I wonder if he has even heard of induced demand
I doubt he’s ever heard of it Matt. There’s an interesting leap of faith that widening a motorway will “fix congestion” once and for all. You would think that after this not working again and again and again that we’d learn the error of our ways in this blind belief – but clearly not.
PS – this is the 9000th comment on this blog. Yikes!
I think half the problem is he grew up in New Plymouth and now lives on a lifestyle block north of Albany, and has an extensive background in running media companies and no background in transport at all. He has no personal experience with living in a large city, and seems to just apply small town approaches to transport. I suppose if the main road into New Plymouth is congested you could probably fix that by widening, likewise he can only ever drive to go anywhere from his house, so he assumes other people are the same.
Remember this was NZTA Chief Executive Geoff Dangerfield who said this though, not Steven Joyce (on this occasion).
Perhaps I’ve never travelled across the Mangered brige enough, but I honestly can’t recall a time in my life when travelling to the airport that this bridge slowed down our journey due to slow traffic. At 700 odd metres the bridge takes around 30 seconds to cross at 80km/hr – I fail to comprehend how having 4 more lanes is going to make me go back in time 19 1/2 minutes when I drive across it next time?!?…
Google driving directions states it takes 35 minutes to get from the CBD to Auckland Airport, like you’ve pointed out, it seems that NZTA is trying to tell us that by 2013 when the WRR is open it will take a total of 1 minute to reach the airport from downtown due to 20 minutes of time saved due to the new bridge and 15 minutes saved due to the Waterview tunnel.
How can people like this be in charge of mind-boggingly huge sums of money?
I lived in Mangere Bridge for 23 years, and hope to god this helps ease the friday night traffic build up that happens, and understand that if it does, it will be for a few years at best.
Myself and a lot of family/friends who live in the area are just plain baffled as to why a railway line wasnt built across it at the same time, time will tell.
Len Brown: Big opening of the new bridge over the Manukau harbour this morning. The completion of the western ring road is well on the way. Took the opportunity to reiterate the need to deliver with pace, the plan for rapid rail for our region, rail to the airport, complete the inner city loop, and rail across the Waitemata harbour to the shore.
11 hours ago · Comment · Like
10 people like this.
Eddie Manukau Fast Forward being the key………..
11 hours ago · Like · 2 people
Julie Fairey My toddler kept insisting there should be a train when we walked across.
10 hours ago · Like · 1 person
Glow Worm Funny how the young are so good at stating the bleeding obvious…
8 hours ago · Like
What’s the point of rail to the airport if the trip (at least on paper) has been reduced to virtually nothing in a car?
Awsome, so once these two are finished and the planned upgrade of SH20A to motorway standard has been done we’ll be able to arrive at the airport 7 minutes before we leave the CBD! It all sounds like a Douglas Adams novel.
…perhaps they do realise that time savings are fleeting. For example Mangere Bridge widening saves 20 minutes, but it is all gone by the time Waterview opens, Which means they can claw the same 20mins back again for a few months, before moving on to the next project to save 20mins. Eeek, it all just means a constant program of motorway projects is needed just to keep traffic in check, sounds all very familiar.
Is there any “road congestion index” we can use to measure congestion with? If so it will be great doing posts looking at the impact motorway widening projects have on congestion. If not we will have to use average daily traffic divided by number of lanes.
It will be interesting doing a comparison in 10 years time.
Its a shame you didn’t do a timed trip across the mangere bride a few weeks ago so you can do another one today to see if there really is 20 minutes faster trip.
I fail to see how a 30sec trip could be any faster…
“At 700 odd metres the bridge takes around 30 seconds to cross at 80km/hr”
“I fail to see how a 30sec trip could be any faster…”
In their defense (or more woe on us, whatever you like), they also widened and added lanes to many kilometres of the motorway on each side of the bridge (and the two suburbs north and south of the bridge also added back-and-forth traffic to some degree). So it’s not just the bridge itself that will speed up (for a while) but also the motorway itself, where the bridge in recent times had become the bottleneck.
Of course now that this bottleneck is fixed, and traffic will indeed flow faster for a few years, why would a worker at the Auckland Airport or in Favona NOT drive there, rather than take a crappy bus service taking him much longer? Induced demand: here we come. Airport rail: Here we go – just reduced the likelihood of rail happening again (notwithstanding the bridge foundations being strengthened somewhat for a future line).
I feel pretty bad harping on about this, knowing that the folks who built this bridge are such great and efficient people. But I’d rather see their skills employed in building railway lines, busways and green transport corridors (walking & cycling routes).
I think the NZTA are getting ahead of themselves. Maybe, on a good day, you might get a 20 min saving once the Waterview connection is done, and as Nick says, most of SH20A is upgraded to a motorway. Until then, it will probably be quicker from the CBD to use SH1 then onto the the new SH20 Manukau connection when it is opened soon.