FAQ on the Waitematā Harbour Bridge Proposal

This is a guest post by Nicolas Reid, Technical Director – Public Transport and Rapid Transit at MRCagney and author of Transit By Design.

In this post – shared by kind permission (via Linkedin), Nicolas answers a number of frequently asked questions regarding his proposal for the next Waitematā Harbour crossing.

As we said a few weeks ago, this proposal strikes us smart, affordable, deliverable, and delightful. A multi-modal bridge, designed to complement the existing one, enabling freedom of movement for all kinds of journeys. A brilliant bridge like this – built beautifully – would be an iconic addition to our great harbour city.

This conversation belongs to everyone in Auckland, and we think this bridge proposal is a great one.

A few weeks ago I posted our concept for a multimodal bridge in Auckland, as a smaller-scoped, more affordable yet high benefit solution to the next Waitematā Harbour Crossing. Naturally that kicked off quite a lot of robust discussion!

I’ve had many questions from people asking about what it is we’d come up with, where it goes and why, so I thought I’d write up an FAQ and post here. I’ve also added a couple more diagrams with more details like everyone was asking for.

So let’s keep the discussion going. Please add your ideas, opinions or critiques in the comments below, plus any further questions or clarifications. I’d love to hear what you think, what we have right and what we have wrong.

What is proposed?

A multimodal bridge with rapid transit, motorway lanes, plus walking and cycling. In combination with the existing bridge, the Waitematā bridge would effectively add across the harbour:

• Two new rapid transit lanes (busway to begin with, then light rail or metro)
• Two new bus lanes
• Two extra counterpeak motorway lanes
• Separate walking and cycling paths

It would allow the motorway to run at four lanes each way at all times, dedicated to carrying state highway lanes through to SH1, SH16 and the port. There would also be two lanes dedicated to traffic accessing the city centre and central suburbs. The state highway lanes would be separated from the city traffic lanes to a large extent, effectively bypassing the city centre and city commuter traffic queues. The movable barrier system would no longer be needed, as the current peak traffic capacity would be available in both directions at all times

The motorway lanes on the new bridge would be four lanes southbound, leading to the four lanes on the Victoria Park flyover. However, during planned maintenance, the new bridge would run as two motorway lanes in each direction. Initially this would allow the original harbour bridge and then the clip-ons to be closed in long stages for major renewals, while still keeping the same lane capacity as today.

What isn’t proposed

This proposal doesn’t add any more peak direction traffic capacity. The traffic lanes that are added are for the motorway in the counterpeak direction, and interpeak. This aligns the motorway lanes across the harbour with the capacity of the motorway on both sides at all times. It takes advantage of the spare capacity afforded by the current movable barrier design, but allows the maximum use of the existing state highway network both ways, not just in the peak direction.

This bridge also doesn’t add any extra off-ramps or traffic capacity to the city centre or local streets – getting more cars into town is not part of the design concept.  However, city traffic may flow a bit more freely given less interaction with the motorway and vice versa.

The existing car commuter access to the city centre is maintained, but a huge amount of additional capacity is provided with the rapid transit lanes from the upper North Shore, the dedicated bus lanes from the lower North Shore, plus the walking and cycling links.

Is the bridge the pinch point, or the approaches?

Like the often repeated myth of the ‘planning disaster’ that led to the Auckland Harbour Bridge being doubled in width with the clip-ons, there’s also a truism going around that the Harbour Bridge itself isn’t the problem for traffic congestion, it’s the approaches that are the pinch points.

That’s not really true, because the congestion occurs where the approaches narrow down to meet the pinched capacity of the bridge.

The harbour bridge is eight lanes wide. Meanwhile, the motorway either side of the bridge is ten lanes wide for general traffic, and twelve lanes wide when you count the bus lanes and dedicated off-ramps. To put it simply, there is already considerably more capacity in the highway and busway network either side of the harbour bridge than on the bridge itself.

We already have five motorway lanes in each direction leading to and from the bridge because of the movable barrier system. This shifts the eight lanes on the bridge to be five in the peak direction, and three in the counterpeak direction…. Which means that going north in the morning or south in the afternoon means experiencing the traffic that results from squashing five lanes and the buses into to just three lanes over the bridge.

To be blunt, that’s a 20th Century approach to traffic management aimed at prioritising car commuters driving to office jobs downtown, one that’s no longer the most efficient outcome, and it’s a big part of the current problem: we actively take lanes away from the strategic state highway corridor to give them to single occupant commuters going to downtown.

Why build a new crossing near the existing bridge?

A bridge from the North Shore to the city centre is exactly where it is needed to complete the missing rapid transit, walking and cycling crossings of the harbour.

It’s also where there is spare counterpeak capacity on the motorway that can’t be used currently, leading to traffic congestion that is as bad going north in the morning and south in the afternoon as it is in the peak direction.

It’s also what works best in conjunction with the current bridge to get buses and private vehicle traffic to the city centre and central suburbs.

Putting a new crossing anywhere else requires pushing motorway or local roads through existing city neighbourhoods or suburban areas to reach it on both sides, plus the addition of new rapid transit lines and walkway and cycleway links. That means many kilometres of house demolition and road building, or many kilometres of very expensive tunnels and viaducts.

Why not right alongside the existing bridge?

This is an option that some people prefer, based on the idea that a new bridge will blend in with the old one and have fewer physical or visual impacts. It also means a slightly shorter bridge.

However, the route overall is longer than going straight across the harbour. In particular, it requires adding extra lanes for the new modes along 1.5km of waterfront through Saint Mary’s Bay, in an area that is already very constrained. This would have big impacts on Westhaven Drive, the marina access and what remains of St Marys Bay beach.

Likewise on the northern side, there would more impacts on Northcote Point. The direct route across the harbour skips St Marys Bay entirely, and in fact would allow the current roadway to be reduced by three lanes in width, freeing up space to make public realm improvements to the waterfront.

Why a bridge and not a tunnel?

In short, bridges are lot cheaper than tunnels. That means a bridge is both more affordable in the first place, and better value for money in the second.

It also makes for a smaller and shorter construction programme with less risk, shaving years off the build and reducing the likelihood of lengthy delays and costly blowouts.

As well as being faster and cheaper build in the first place, bridges are much cheaper to operate day to day. Long tunnels have an extra layer of fire and life safety risks that mean much greater monitoring and control systems, more arduous evacuation requirements, and more frequent service disruptions to manage them.

All else being equal, a bridge will have more robust operations than a tunnel on the same corridor, which translates into higher capacity too.

We’ve proposed a cable-stayed bridge because this looks to be the best design for the context. Cable-stayed bridges are strong and stable, and they can span significant distances across water without needing dozens of piers driven into the seabed. They are resistant to wind loading and suitable for earthquake zones.

Most importantly, cable-stayed bridges can be built relatively quickly and cheaply without the need for falsework supporting the deck from below. Having said that, I’m definitely not a bridge engineer and am interested to hear if there are better approaches.

What about rail?

This bridge proposal is compatible with several options for bus and rail to run in the rapid transit lanes. The width of the rapid transit lanes and the grades of the bridge and its approaches are suitable for Auckland’s’ current conventional busway buses, as well as special rapid transit buses, light rail or metro rail.

The most pragmatic option is to use these lanes to extend the existing busway across the harbour to the city centre, as much of that infrastructure already exists, and the improved busway would perform very well.

Light rail would be an excellent outcome with improved performance and capacity, but it would require adding at least the first stage of a light rail network to the harbour crossing project, a big increase in scope. Likewise metro rail would be a very high-performing option, but it would come at a very high additional cost added.

Light rail or heavy rail could be part of the harbour crossing programme from the start, or they could be added as a subsequent stage.

Heavy rail is not proposed, as allowing for it would add a huge amount of cost to the crossing for little extra benefit. The North Auckland Line already carries heavy freight north around the harbour, while the transport needs of the North Shore are better served by rail modes specifically designed for urban rapid transit.

Heavy rail built to mainline specifications does not fit within the proposed bridge design envelope as it is proposed. It requires broader curves and shallower grades than what light rail or metro rail designed just for urban passenger transit is capable of. In simple terms, Heavy rail would require structures that are twice as long so they can be half as steep, and curves that are twice as broad. This design constraint isn’t just for the bridge crossing itself, but the approaches to it.

Furthermore, there isn’t spare capacity in the rail network or the City Rail Link to add in an extra heavy rail line from the North Shore. The capacity of the city tracks and stations is all planned to be utilised for the existing lines. This means heavy rail across the harbour would also require expanding the scope to include an equivalent to a second City Rail Link to connect the harbour crossing to the city centre.

Will this proposal fix the traffic?

No infrastructure project will fix peak traffic congestion, but this will ease the level of congestion, reduce the impact of commuter traffic on the state highway, and stop it spreading as much across the day. It will reduce the impacts of delays and disruptions.

More importantly, it would let a lot of current and future residents travel quickly and easily without being in traffic at all. The improvements to buses, rapid transit, walking and cycling would allow hundreds of thousands more people to cross the harbour each day without contributing to traffic congestion at all.

Does it do everything we will every need?

A new bridge will last a hundred years. It might not solve all our transport problems for a hundred years, but it will still keep working and moving tens of thousands of people per hour for all that time. With a relatively small scope and cost, this can be the next step in a longterm programme of improvements. It won’t necessarily be the last crossing improvement ever built, and it doesn’t need to be.

Will a business case reveal the most efficient outcome?

Unlikely. Business cases tend to land on the most effective outcome regardless of efficiency or affordability. It’s an unfortunate outcome of the current planning process that business cases effectively only lead to one conclusion – the biggest most expensive outcome.

Business cases aim to eliminate a smorgasbord of often-competing problems and achieve maximal benefits across them all, trying to do everything in one project. This means doing more and more, a process looking for the biggest solution. The more problems you can come up with, the bigger the solutions are, and the better the business case.

In this process, the real cost of a project is only worked out after the problems are defined, the concept has been selected and the engineering solution is designed. Cost-effectiveness has little input into the design and evaluation process, and affordability is often disregarded as simply “that’s what it costs to fix the problem”.

This approach encourages scope creep, leading to massive projects that are unaffordable, poor value for money, high risk, and have very long timeframes to build and implement.

What is needed for a crossing that we can actually afford?

A better approach is to look the main issues and the main benefits, and find the smallest project that works with the existing context to solve most of the problems, with a close eye on the scale and cost of the project as part of the design process.

That leads to more affordable and more cost-effective projects with lower risk and shorter implementation times.

The motorway and public transport connections on the North Shore. Motorway lanes in blue, city access lanes in orange, bus lanes in green. New embankment with rapid transit and active modes in red.

The Waitematā Bridge and Auckland Harbour Bridge, and connections to existing network at Fanshawe Street and the Victoria Park Viaduct and Tunnel.

I hope that answers the main questions so far. Once again, please do add your ideas, opinions or critiques in the comments below, plus any further questions or requests for clarification. I’d love to hear what you think, what we have right and what we have wrong, and what else to think about.

– Nicolas Reid

If you’re keen to support Greater Auckland’s work pushing for a brilliant, beautiful bridge as the heart of a top notch 30-year transport plan for our city, you can donate here. And as always, please feel free to share our work widely. This conversation belongs to ALL Aucklanders, and we all deserve to be part of it!

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