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An Alternate East-West option

This page originally comes from post in November 2013.

Late last week we detailed a couple of options about the East-West link. The first was a suggestion by a local business group involving an 8 lane motorway between Onehunga and Highbrook which was primarily along the northern edge of the Manukau Harbour and while it is pretty extreme, isn’t overly that much different to the official Option 3. The second we looked at was Option 4 which was a motorway between Highbrook and the Mangere end of SH20A which would result in over 500 houses needed to be demolished.

Before I go further that I think it’s worth pointing out that just because I don’t agree with the motorway proposals that it doesn’t mean I don’t agree that something needs to be done in the area to improve transport. So I guess the question really becomes – what would we do differently?

Firstly as I mentioned there is definitely an issue that needs to be addressed. The presentation from earlier in the year shows that Neilson St in particular is one of the busiest freight routes in the country carrying more freight than any other local arterial and more than most of the RoNS as shown by the image below. There are also some fairly high traffic volumes on the nearby South Eastern Arterial (SEART).

East-West Freight movements

The next image from the presentation shows where the main traffic flows are

East-West Key Movements

AT also monitor travel times along the route that is Neilson St – Church St – SEART – Ti Rakau Dr and say that travel times along the route are unpredictable with the worst sections being Onehunga Mall to Captain Springs Rd, Beasley Ave to Gt South Rd and around Harris Rd in East Tamaki. I would classify Auckland Transports current four official options as either trying to make alternative routes more attractive with some local upgrades and a few new connections or massive duplication of what already exists through new motorways being options 3 and 4.

What seems to be missing is improvements to the existing route and when you look at the route closer it seems much more could be done.

Onehunga Mall Area

AT say that work has been going on to improve the Neilson St section between the SH20 off ramps and Onehunga Mall by widening it and the NZTA have recently finished upgrading the southbound on-ramp. Long term the documents indicate that the NZTA want a diamond interchange on to Neilson St which would likely simplify the Onehunga Mall intersection but I have heard the tried to get that when the harbour crossing was built but that it was denied consent. As such vehicles using the northbound on/off-ramps need to use Onehunga Harbour Rd. I wonder if longer term a connection could be made to the southern section of Galway St which would likely take pressure off that intersection. The current routes are shown below in red and blue while the connection I’m suggesting is in yellow.

East-West Onehunga Mall interchange

Neilson St

On Neilson St to the east of Onehunga Mall travel times are still an issue and when you look at a map you can see that the road drops down to a single lane – but a really wide one – all the way through to the intersection with Church St. To go further, we also know that freight movements are incredibly important in comparison to moving single occupant cars and so why not make that newly added lane a truck only lane allowing heavy vehicles to bypass the traffic if there did happen to be congestion. Further if Metroport is an issue – which people seem to say that it is – then a signalised intersection could be added to assist trucks from there to get into and out of the port. The total section to be widened is less than 2km and shown in blue while the Metroport entrance is the red dot.

East-West Neilson St widening

Church St – SH1

I’ll deal with the motorway next but this section seems to be the trickiest as the route is already four lanes wide and there are three major and likely difficult intersection with Neilson St, O’Rouke Rd and Gt South Rd. In addition the road also needs to cross over the rail line which further adds to the constraint. It is this section where probably the majority of the money needs to be spent. I’m normally against this in an urban area but I think we should perhaps consider grade separating these three intersections. The intersections do splay out a bit to provide turning lanes however there would still probably need to be some land take effectively ramps the bypassed roads but that would certainly be much less than if we needed to take land for a brand new all the way from Onehunga to Highbrook. The purpose of these three grade separated intersections would be to prioritise the through movement, both East-West but also North-South along Gt South Rd. Again the route is shown in blue and the intersections to be potentially grade separated are in red.

East-West Church St

SH1

For trucks heading between Onehunga/Penrose and the commercial areas to the east of Sylvia Park the SEART provides a connection through to Carbine Rd while trucks heading south towards Otahuhu can use Gt South Rd. However one of the major problems is for trucks travelling between the Onehunga/Penrose area and Highbrook as currently the only real option is to detour along local roads to get to the Mt Wellington interchange. To address this south facing ramps directly from SEART to SH1 could be considered. This would save about 1km in distance but also cut out a number of intersections so probably provides a lot greater time saving than just that.

The downside is that extra work is likely to need to be done so that any vehicles using these ramps don’t cause issues with the north facing ramps on the Mt Wellington Hwy interchange. This would most likely require the ramps to be weaved. In addition the bridge crossing the Mt Wellington Hwy would almost certainly need to be widened.

In total it would look something like this with the blue line being the current route for trucks heading south with the yellow being the new connections added. To get to Highbrook they would just use the motorway and the interchange and connection built not that long ago.

East-West SH1

Cost

The big thing in favour of this option would likely be the cost compared to the other full scale options. These are admittedly guesses but let’s say:

  • Onehunga new connection – about $2o million.
  • Widening Neilson St – $15 million
  • Church St – $30 million per interchange = $90 million
  • SH1 connection including Mt Wellington Hwy interchange upgrade – $100 million.

So all up we are have a total of ~$240 million and we have significantly upgraded the route which would then look something the blue line below while the red line represents Option 3 and the Yellow line Option 4. To put that into context I have heard suggestions that each of these could cost in the vicinity of $1.5 billion or more.  Sure Option 3 in particular is a much shorter route but is it really worth spending what could be ~$1.2 billion just to get that last bit of savings while causing massive disruption in the process. What’s more even if in the long term we do need something like Option 3, upgrading the existing route could put off the need for the project by decades saving us huge amounts in the meantime or we could put the motorway plan money to better use elsewhere.

East-West Total

In summary let’s focus on the existing route through a series of upgrades to both the road and to the intersections, possibly even grade separating some of them. Let’s see what kind of impact a concerted effort to improve the corridor can have before we jump straight to the nuclear option of more motorways that plough through residential neighbourhoods. If after all of that we still need the motorway solution then we can look at it again however that doesn’t mean the work suggested above will be wasted, just that it will have a different use.

Lastly if the road transport and business groups still think the motorway options are the best then it might also be worth someone asking them just how much of a toll they would be prepared to pay to use it, or are they expecting everyone else in the city/country to pay for it? I’m not saying it has to all be paid for with toll money but if the trucking companies aren’t prepared to pay for a substantial amount of it through tolls then you have to wonder just how valuable the road is to them over a more standard upgrade as suggested above.