By Ed Clayton. Part 3 of a 3 part series
Part Two: Guest Post: Auckland’s Urban Freshwater – the Water Sensitive City (Part 2)
Welcome to the third (and final) post in this three-part series. The first two posts looked at the historic state of Auckland’s relationship with freshwater and the concept of the water sensitive city – what a future sustainable city might mean in terms of freshwater. This post reviews our existing transport network and what our current priorities are. It takes concepts of the water sensitive city and then makes the case for a low-carbon rapid-mass-transit system for Auckland’s future.
It is no secret that Auckland has spent the last 70 years investing in private vehicle transport to the detriment of other networks. In the last ten years we have seen a push to complete the motorway network. While we have had public transport successes, such as the Northern Busway, electrification of the rail network and the start of the Central City Rail Loop, funding and government support for these projects appears to be harder to come by (this is changing under the current government).
Motorways are expensive to build. And, with the excellent work recently done by Greater Auckland investigating the costs of past, current and future projects, they are likely to become more expensive with diminishing returns1. Motorways are also dirty. Auckland Council recognises that any road carrying more than 10,000 vehicles per day is a High Contaminant Generating Activity2 (this actually includes arterial roads within the city too). Mitigation of contaminants is required before water can be released to the environment. Swales and detention basins are the most common Low Impact Design infrastructure used to achieve this, but there is some degree of discussion as to how successful these devices are during low-frequency high-magnitude events (i.e. a 1 in 50 or 1 in 100 year storm) where pollutant transport is generally highest3. It is also becoming recognised that some degree of traffic congestion is an inevitable part of a successful city economy4. So, if building more roads is just going to induce demand for more roads, why do we keep doing it?
If we return to discussion points from the first two posts in this series, we now have a problem with our current transport system and the Water Sensitive City concept5. We still externalise a lot of environmental costs associated with transport. We are still doing the ambulance at the bottom of the cliff, to borrow a well-used phrase. The freshwater ecosystem service we value here is still waste removal, albeit slightly mitigated compared to 50 years ago. Pollution from vehicles is still primarily discussed in terms of air pollution, not water pollution. While electric vehicles will reduce some of the air-borne pollutants associated with motorway traffic (tail-pipe emissions) they do not address major sources of water pollution such as tyre wear. Tyres are full of toxic compounds designed to make them harder wearing and longer lasting6. Recent work suggests that tyre wear may contribute 30% of micro-plastics to the world’s oceans7.
So what would be the transport network of a Water Sensitive City? Can we just have motorways and arterial roads with electric vehicles, swales, bioretention devices and permeable pavement? I don’t think we can. And I don’t think bus rapid transport is sufficient for much the same reasons. Some permeable paving struggles to cope with heavy vehicles8 and where it can, the noise generated from high speeds would be deafening for people inside vehicles. Bus transport still results in tyre wear and tail-pipe emissions. Mitigation of runoff still requires land external to a road corridor to provide the detention and treatment services. We need a transport system that is low emission (even no emission, 100% renewable energy powered), does not require a large physical footprint, does not produce large quantities of pollutants and is hydrologically neutral. Light rail can do all of these things.
I know there has been much discussion recently on Greater Auckland around the comparative benefits of light and heavy rail, especially as the preferred option to connect to the airport. This post is not about that comparison. This is about reasoning that instead of bus rapid transit (e.g. Northern Busway and the Congestion Free Network), we should just go straight for light rail. Luckily the change in government is supporting light rail to the airport and out west. But I would argue that we should eventually replace most, if not all, of the major bus corridors across the city with light rail. The Airport to Botany Rapid Transit line would be a great example of doing the right thing first time. Ambitious sure, but let me explain.
If we consider freshwater as underpinning the māuri of a place (as we should), it makes sense to plan our city around this. Freshwater is a resource and we must consider the complete water cycle when we build infrastructure. A transport network that does not have a neutral impact should not be built. Mass transit moves more people per ‘lane’ of network than private vehicles (as proven by the Northern Busway that delivers more people to the CBD than the northern motorway). However, Bus Rapid Transit will create the same types of freshwater pollutants as private vehicles. Light rail does not. Runoff from motorways has been observed to be ten times more polluted than traditional light rail designs9. I believe, with careful design, surface water runoff from light rail could be reduced to a hydrologically neutral condition (i.e. no different from a natural catchment) and with a greatly reduced pollutant load.
Traditional road surfaces are close to 100% impermeable. Almost all rain falling onto the surface runs into drains and gutters. If it doesn’t, and seeps into cracks and fissures in the road surface, wear of the road surface is accelerated, with resulting potholes and other such damage to the surface. Permeable paving is not yet suitable for roads where high speeds and heavy vehicles are present. Road surfaces need to be uniform as vehicles do not follow exact paths (lane changing, movement within lanes etc). Contact surfaces between vehicles and the roads surface need to be large to create enough friction to enable control of the vehicle (large tyre surfaces).
Light rail, on the other hand, can eliminate impervious surfaces within a transport corridor. Light rail units must run on tracks, so follow a predefined path. No tyres, so no tyre wear. They also have a low area of contact within the width of a lane. This leaves the rest of the corridor with no purpose. Usually, if in a corridor of its own, this might be track ballast. Or, if within a road corridor, just normal road surface. But what if we decided to give this area a purpose, make it multi-use? Biofiltration such as swales or rain gardens within a light rail corridor could provide much needed attenuation and filtration of surface water. The idea of ‘lawn trackage’ is not new, although deliberate use of these green swards as biofiltration and water treatment facilities is not always a designed service. Great examples are already in place in several cities, Lyon and Brussels being two of them.
A light rail line consisting of lawn trackage interspersed with raingarden pits would provide detention and infiltration of stormwater and allow recharge of groundwater. If our existing and planned Bus Rapid Transit networks were repurposed to be light rail we could use this network to provide stormwater treatment areas for adjacent road surfaces. Expanding this idea to all dual carriageway arterial roads in Auckland, we could remove one lane of traffic in each direction and have modern light rail running down the centre of each arterial road. This would move more people within existing transport corridors and reduce the impact of road runoff. Think of Melbourne’s network, but with more green surfaces.
This also provides opportunity for placemaking and interaction with freshwater. The perfect example is Queen Street. There is already an Auckland Council Technical Report that investigates ‘daylighting’ the Waihorotiu (returning the stream to the surface), along with three other central city streams10. If Queen Street became a pedestrian, cycling and light rail corridor (along with the extension of light rail along the Dominion Road corridor and further), it would create the chance to open the street up and refocus this heavily used area to be orientated to the Waihorotiu and the interaction of the freshwater and marine environments at the original shoreline. We need to see our freshwater environment to value it. Imagine if you could go to Queen Street and see inanga and other whitebait swimming upstream, eels in the Aotea Square wetland and koura in Myers Park? And clean freshwater means clean marine water, so beaches don’t have to be closed after it rains.
I understand that the network that I have proposed would be expensive. I know that it would take a long time to implement. Funding such a network is not something I have costed. But I would argue that we have never fully understood the costs of our motorway network either, and if we factored in the costs of ecosystem services into large roading projects (and the clean-up of existing pollution) then light rail just might not be so bad.
I think we are at a crossroads now in Auckland. If we keep building as we are, we will never achieve a sustainable, resilient urban fabric. And I know it is economically appealing to look at Bus Rapid Transit as the first step on the path to light rail. However, building one type of transit to then rebuild another overtop later on is ultimately more expensive. And we seem to be addicted to building public transport infrastructure slowly and piecemeal, if at all (the North-western and Eastern busways anyone?). We need to limit city expansion for many reasons, not least that we need to preserve our existing freshwater resources. Good active and public transport choices represent a democratic transport system where the needs of all citizens are catered for11,12. This goes hand in hand with thoughts from Emma McInnes about designing cities where women, children and people with disabilities feel comfortable and safe13. Providing a successful, connected, resilient transport network needs to happen now.
It will require a change in attitude. Funding must come from somewhere, and given the historic under-investment in Auckland, it is time that central government stumps up. But Auckland needs to too. Rates in Auckland are low. Maybe we need to sell this as an investment in our future? Local government bonds? There are many voices calling for changes to our infrastructure to make it climate-change resilient14,15,16. And we have just seen the latest IPCC report on how we need drastic changes to our social, economic and cultural landscapes to lessen the impact of climate change17. The current government is much more supportive of public transport, so lets make sure it gets built in a way that values freshwater.
So, how do you feel about freshwater? Is it a resource that we don’t value, or a nuisance that we need to get rid of? Do you think the interaction between our current transport system and freshwater is good enough? Why do we start with transport infrastructure that is known to pollute and then try to reduce the impacts, rather than design infrastructure that doesn’t pollute?
I’ll close these posts off with a quote from ecologist Paul Shepard in Rachel Carson’s Silent Spring18, still valid after 50 years:
“Why should we tolerate a diet of weak poisons, a home in insipid surroundings, … , the noise of motors with just enough relief to prevent insanity? Who would want to live in a world which is just not quite fatal?”
Acknowledgements: These posts have benefited from the careful review of many people and my thanks go to you all, especially to Martin Neale, Emma Fergusson and Riki Taylor.
References and further reading:
- Auckland Council, (2013) Auckland Unitary Plan stormwater management provisions: Technical basis of contaminant and volume management requirements, Prepared by Auckland Council, Auckland Council technical report, TR2013/035
- Bhaduri, B., Harbor, J., Engel, B. & Grove, M., (2000) Assessing Watershed-Scale, Long-Term Hydrologic Impacts of Land-Use Change Using a GIS-NPS Model, Environmental Management, 26(6), pp643-658
- Wong, T.H.F. and Brown, R.R., (2009) The water sensitive city: principles for practice, Water Science & Technology, 60(3), pp673-682
- Wik, A. (2007) Toxic Components Leaching from Time Rubber, Bulletin of Environmental Contamination & Toxicology, 79, pp114-119
- Sommer, F., Dietze, V., Baum, A., Sauer, J., Gilge, S., Machowski, C. & Giere, R. (2018) Tire Abrasion as a Major Source of Microplastics in the Environment, Aerosol and Air Quality Research, 18, pp.2014-2028 https://www.sciencedaily.com/releases/2018/09/180910160635.htm
- Scholz, M. & Grabowiecki, P., (2007) Review of permeable pavement systems, Building and Environment, 42, pp3830-3836
- Sajjad, R.U., Kim, K.J., Memon, S., Sukhbaatar, C., Paule, M.C., Lee, B.-Y. & Lee, C.-H., (2015) Characterization of Stormwater Runoff from a Light Rail Transit Area, Water Environment Resources, 87(9), 813-822
- Lewis, M., (2008) Stream Daylighting: Identifying Opportunities for Central Auckland – Concept Design, Prepared by Boffa Miskell for Auckland Regional Council. Auckland Regional Council Technical Report 2008/027;
- Sagaris, L., (2010) From sustainable transport development to active citizenship and participatory democracy: The experience of Living City in Chile, Natural Resources Forum, 34, 275-288
- Shepard, P., in Carson, R. (1962) Silent Spring, (p.12), Houghton Mifflin, New York
Note from Admin: my thanks to Ed Clayton for his guest post series. If you would like Talking Southern Auckland to host a guest post on issues concerning Auckland and particularly Southern Auckland feel free to send an email