Could burying the M32 solve Bristol’s pollution problem?

The M32 in Bristol. Image: Dun Holm/Wikipedia Commons.

The world may have possibly found a solution to climate change in an unexpected place: the west of England metro mayoral race. It seems that Lesley Mansell, the Labour candidate, let slip what could be a universally applicable method for stopping motorway emissions.

“You could potentially put the M32 underground and then reuse the space on top,” Mansell said at a hustings event held last month by the Bristol Post. “It might seem like a wild idea, but sometimes those off-the-wall ideas can have some positive outcomes. It would be much better if you have got the traffic underground, as we wouldn’t have the carbon going into the atmosphere.”

Of course, it’s a terrible idea. Mansell is possibly correct that the move would create extra space, and she’s possibly correct that wild ideas can work out really well. It’s just that last point where the idea starts to fall apart, as tunnels don’t possess any carbon-destroying abilities.

“[Carbon dioxide] would not be removed by a road tunnel and would consequently emerge into the local atmosphere from the ends of the tunnel,” says Roy M. Harrison, professor at the University of Birmingham’s School of Geography, Earth & Environmental Sciences. There  are many actions we can take to fight climate change, but burying one of the country’s shortest motorways is not one of them.

The M32. Image: Open Street Map.

The motorway is something of a local frustration. Built in 1966, it stretches just 4.4 miles from Bristol’s city centre to the M4 at junction 19. Bristol City Council has tried before to convert it to an A-road, but to no avail. The M32 even has its own entry on PatheticMotorways.org, which documents Britain’s most ridiculous motorways.

Oddly enough, the city council has not ruled out Mansell’s idea. A spokesperson told the Bristol Post that a new congestion task group will be launched soon, aimed at exploring ways of how to improve transport in the local area.

“No decisions or firm plans have been made at this very early stage,” the spokesperson said.

If the task group opts to build a tunnel, for whatever reason, it wouldn’t stop pollution per se, but it would help shape the escaping pollutants. Ventilation shafts would be needed to maintain a somewhat breathable quality of air inside the tunnel. Because of this, building a tunnel would essentially concentrate emissions around a set number of extraction points, rather than allowing them to freely disperse into the atmosphere.

“You could probably build a tunnel with ventilation shafts that suck the air out and have it scrubbed of pollutants,” says James Lee, professor at the University of York’s National Centre for Atmospheric Science. “But I would imagine this would be a very expensive option.”


A tunnel could, in limited circumstances, stop certain emissions from entering the atmosphere. That’s because particles are created from three different sources on cars: combustion, brake wear, and tyre wear. The tunnel would not stop the first kind from leaving, due to their gaseous nature; but the other two could stick to the tunnel walls.

“The reduction in particle loading because of adhesion to the tunnel surface wouldn’t be a particularly effective control technology,” said James Longhurst, professor of environmental science at the University of the West of England.

But it would be wrong to say that city planners never consider tunnels as a method of maintaining acceptable air quality levels. If building a new road would otherwise push an area past national or European requirements for individual pollutants, placing it underground allows designers to concentrate emissions through the shafts, towards areas where the quality is less of a concern.

This is less of an issue with the M32. Bristol’s Air Quality Management Area, a designated zone that local authorities monitor to ensure they meet pollutant targets, only covers a small section of the motorway. The city council is more concerned about the amount of pollution around the city centre, so using a tunnel to manage air quality would do little to help in the areas where it’s needed most.

“The idea of a tunnel is not something one should remove from one’s thinking,” says Longhurst. “It’s just that in the case of the M32, the cost would be very substantial.”

So yes, in very limited circumstances a tunnel can help with air quality management – but no, they don’t stop carbon emissions.

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The Thessaloniki dig problem: How can Greece build anything when it’s swarming with archaeologists?

Archaeological finds on display in an Athens metro station. Image: Gary Hartley.

It’s fair to say that the ancient isn’t much of a novelty in Greece. Almost every building site quickly becomes an archaeological site – it’s hard to spin a tight 360 in Athens without a reminder of ancient civilisation, even where the city is at its ugliest.

The country’s modern cities, recent interlopers above the topsoil, serve as fascinating grounds for debates that are not just about protecting the ancient, but what exactly to do with it once it’s been protected.

The matter-of-fact presentation that comes with the many, many discoveries illustrates the point. Athens often opts to display things more or less where they were found, making metro stations a network of museums that would probably take pride of place in most other capitals. If you’re into the casual presentation of the evocative, it doesn’t get much better than the toy dog on wheels in Acropolis station.

That’s not even close to the extent of what’s available to cast an eye over as you go about your day. There are ruins just inside the city centre’s flagship Zara store, visible through the glass floor and fringed by clothes racks; Roman baths next to a park cafe; an ancient road and cemetery in an under-used square near Omonia, the city’s down-at-heel centre point.

Ruins in Zara. Image: Gary Hartley.

There is undoubtedly something special about stumbling upon the beauty of the Ancients more or less where it’s always been, rather than over-curated and corralled into purpose-built spaces, beside postcards for sale. Not that there isn’t plenty of that approach too – but Greece offers such sheer abundance that you’ll always get at least part of the history of the people, offered up for the people, with no charge attached.

While the archaic and the modern can sit side by side with grace and charm, economic pressures are raising an altogether more gritty side to the balancing act. The hard press of international lenders for the commercialisation and privatisation of Greek assets is perhaps the combustible issue of the moment – but archaeology is proving something of a brake on the speed of the great sell-off.

The latest case in point is the development of Elliniko – a site where the city’s decrepit former airport and a good portion of the 2004 Olympic Games complex sits, along the coastal stretch dubbed the Athens Riviera. With support from China and Abu Dhabi, luxury hotels and apartments, malls and a wholesale re-landscaping of several square kilometres of coastline are planned.

By all accounts the bulldozers are ready to roll, but when a whole city’s hovering above its classical roots, getting an international, multi-faceted construction job off the ground promises to be tricky – even when it’s worth €8bn.


And so it’s proved. After much political push and shove over the last few weeks, 30 hectares of the 620-hectare plot have now been declared of historical interest by the country’s Central Archaeological Council. This probably means the development will continue, but only after considerable delays, and under the watchful eye of archaeologists.

It would be too easy to create a magical-realist fantasy of the Ancient Greeks counterpunching against the attacks of unrestrained capital. The truth is, even infrastructure projects funded with domestic public money run into the scowling spirits of history.

Thessaloniki’s Metro system, due for completion next year, has proved to be a series of profound accidental excavations – or, in the immortal words of the boss of Attiko Metro A.E., the company in charge of the project, “problems of the past”.

The most wonderful such ‘problem’ to be revealed is the Decumanus Maximus, the main avenue of the Byzantine city – complete with only the world’s second example of a square paved with marble. Add to that hundreds of thousands of artefacts, including incredibly well-preserved jewellery, and you’ve a hell of a haul.

Once again, the solution that everyone has finally agreed on is to emulate the Athens approach – making museums of the new metro stations. (Things have moved on from early suggestions that finds should be removed and stored at an ex-army camp miles from where they were unearthed.)

There are other problems. Government departments have laid off many of their experts, and the number of archaeologists employed at sites of interest has been minimised. Non-profit organisations have had their own financial struggles. All of this has aroused international as well as local concern, a case in point being the U.S. government’s renewal of Memorandums of Understanding with the Greek state in recent years over protection of “cultural property”.

But cuts in Greece are hardly a new thing: lack of government funding has become almost accepted across society. And when an obvious target for ire recedes, the public often needs to find a new one.

Roman baths in Athens. Image: Gary Hartley.

Archaeologists are increasingly finding themselves to be that target – and in the midst of high-stakes projects, it’s extremely hard to win an argument. If they rush an excavation to allow the quickest possible completion, they’re seen as reckless. If they need more time, they’re blamed for holding up progress. 

Another widely-told but possibly-apocryphal tale illustrates this current problem. During the construction of the Athens Metro, a construction worker was so frustrated by the perceived dawdling of archaeologists that he bought a cheap imitation amphora in a gift shop, smashed it up and scattered the fragments on site. The worthless pieces were painstakingly removed and analysed.

True or not, does this tale really prove any point about archaeologists? Not really. They’re generally a pragmatic bunch, simply wanting to keep relics intact and not get too embroiled in messy public debates.

It also doesn’t truly reflect mainstream attitudes to cultural capital. By and large, it’s highly valued for its own sake here. And while discoveries and delays may be ripe for satire, having history’s hoard on your doorstep offers inconveniences worth enduring. It’s also recognised that, since tourists are not just here for the blue skies, good food and beaches, it’s an important money-maker.

Nonetheless, glass malls and shiny towers with coastal views rising from public land are good for the purse, too – and the gains are more immediate. As the Greek state continues its relentless quest for inward investment, tensions are all but guaranteed in the coming years. 

This is a country that has seen so many epic battles in its time it has become a thing of cliché and oiled-up Hollywood depiction. But the latest struggle, between rapacious modernity and the buried past, could well be the most telling yet. 

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