BY LIAM HOGAN

Well we laid in the hollows and we laid in the flat

And if it doesn't last forever well I swear I'll eat me hat

Well I've wandered up and down the world and sure I've never felt

Any surface that was equal to the hot asphalt.

There's a delightful Irish (or, perhaps, Scottish) hornpipe, with a jolly melody and a lively beat, which pays tribute to Irish road workers and asphalt layers. 'Hot asphalt/ash-pelt' has been sung by the Dubliners, by the Wolfe Tones, by Ewan McColl and others, and, like any good folk song, has lots of variations. In common to all of them are boasts about 'who can please the ladies best', a verse about leaving home for higher wages, and someone—either a policeman or a boss—who's violently assaulted and dunked in a tub of hot tar. Some variations feature a narrator who is a deserter from the British Army, and in others the narrator's asphalt-preserved corpse is hung in a museum as a scientific exhibit, after he dies of cold. Sex, violence, death: it's got everything a good folk song needs. (And for the researchers, it's listed in the Roud Index as #2134). The only wonder is that there aren't more songs about asphalt.

Asphalt concrete, sometimes called bitumen or (in America) pavement, is the road and footpath surface that defines the modern city, and the roads that link them. Like the Portland concrete used in buildings, it's a mix of an aggregate (rocks, rubble, pebbles, gravel, or anything) with a binding agent (mineral tar, a petroleum byproduct). Like Portland concrete, it's waterproof, it's cheap and easily made in large quantities, and it's hard-wearing—enough—to be very useful.

The one thing we all learn as children is the sheer hardness of asphalt. Every child with scabby knees and elbows has learned the hard way to treat the hard ground with respect. The lessons keep on coming, too. Learner motorcyclists, compelled to attend safety classes, learn about the risks of degloving injury to riders who don't wear protective clothing, a skin and muscle trauma exactly as violent and disgusting as it sounds. 'Bitumen doesn't give a shit', is the blunt advice to riders too fashionable to wear jackets, leather gloves, and full-face helmets.

We experience the road viscerally. Behind the wheel or handlebars of a vehicle, or through the soles of our shoes, we get a lot of tactile information. The road vibrates, hums, squeals, thumps. In bare feet it freezes, bakes, and scratches. Road engineers even use the road surface to give warnings: highway markings sometimes include raised bumps to warn drivers when they're moving out of their lane, and 'rumble strips' perform the role their name suggests to indicate when drivers should slow down.

The relative hardness and toughness of asphalt, compared to alternatives like dirt, gravel, stone, wood, and lime, is what makes it so good for modern vehicles with tyres. It's predictable, even, and waterproof, unlike earlier road material. Cobbles work well enough for pedestrian streets but are hellish at speed on wheels (as riders in the famous Paris-Roubaix bicycle race, for which the trophy is a mounted piece of rock from the road, know). Hard packed dirt and grass is wonderful in the dry, but washes away in the wet, or worse, turns to mud. Gravel, rock, and lime roads offer more permanence—and there are stone roads thousands of years old—but for modern vehicles at speed they're incredibly dangerous and slippery.

It's not well remembered that the first major benefactors of paved roads were not motorists, but walkers and cyclists. Nineteenth and early twentieth century roads were either gravel, cobbles, dirt, or (in some cities) wood. In the horse and bullock era they were liberally coated in dung and urine, and were only cleaned by hand. Most importantly, in the pre-motor age, they were social places where people congregated amongst the traffic, without the very strict segregation between pedestrian and car-space we know now. Public campaigns for better roads, which really meant better road surfaces, were part of progressive and urbanist movements around the world. Asphalt roads could be shaped so that water and debris washed off into drains and gutters, and rolled flat so that rubber-tyred vehicles in turn rolled along comfortably. When cars and trucks started displacing animal traffic, citizens experienced the change as a liberation from streets full of horse dung, unpredictable animals, and the stench of dead beasts. No more muddy horse shit? Wonderful!

Now that we are more familiar with the speed and inertia of cars and trucks, we’ve come to accept exceptionally violent roadscapes. To animals, a road is a barrier between habitats. Crossing carries the constant risk of being unexpectedly crushed, squashed, thrown apart, broken, or turned simply into a pinkish mist of flesh. Roads are a double lure for animals who feed on carrion, like crows, falcons, and Tasmanian devils, who are drawn to the roadside as a food source only to become victims themselves. Local councils and State Governments spend vast amounts of money regularly maintaining the surface of roads, smoothing, repainting, and cleaning. A clean road is testament to workers who're paid to pick up animal carcasses, and to scrub the surface clean of blood and bits.

For humans, the first thing one learns as a child about roads is that you must look both ways before you cross one and, better still, hold the hand of a grown-up as you do. At Easter, on the ANZAC Day long weekend, at Christmas and at other holidays, news services report on the road toll not as a set of individual tragedies but as tally, ticking up. Peter Norton's Fighting Traffic examines the automobilisation of American cities and the compromises we've made with this road violence, in order to both prioritise road space and to contain it. [1] The separation reaches the absolute: cars go in one space, and people in another.

In wartime, asphalt roads become even more violent—and desirable. Mud bogs down armies, and reliable roads make them mobile. Roads have been important to move forces quickly since humans have engaged in organised conflict, but mechanised war makes good road infrastructure critical. Tanks and tracked vehicles can move where they like through the mud, but the road network is itself a military objective, to be captured or defended. With the expectation that air bases might come under attack, many military aircraft are designed specifically to be able to take off and land on ordinary highways. In the hotter periods of the nuclear age, before arms limitation treaties, missiles deployed on transporter-erector-launcher vehicles moved around countries in Europe, America and Asia to avoid detection, turning highway systems into colossal weapons systems—and into targets.

However, the danger and violence that has come with asphalt concrete is somewhat misleading. It is a mistake to view bitumen roads as essentially hard surfaces. In contact with human or animal flesh, it's true, scrapes hurt. In geological terms, asphalt roads are butter-soft. Alan Weisman's The World Without Us makes us think about what would happen to the human world if we weren't in it. [2] At first, without cars, snakes would bask and foxes hunt on the hardtop. The wolves, he writes, would come back to Brooklyn. But eventually, it would, and will, all disappear.

Anyone who lives in a suburb with street trees has seen how easily the asphalt surface breaks when a root system grows up underneath it. Leave a footpath or just a year or two and the flat tape will turn into a cracked, mountainous, bumpy ride full of crevasses and mounds. Where we might see a highway as a permanent black scar across the landscape, seen in the long term it's a thin film of oily stuff stretched tight across some gravelly ballast. In a flood, it washes away; when the earth quakes it cracks like the crust of a pie. When it's hot the surface bubbles, and in the cold it freezes.

As soon as a tiny crack starts, the wear begins. One piece of gravel in a cavity moves back and forth with the rain and wind, working at the sides. Soon there are more and more pebbles eating at the edges of a bigger pothole. Eventually enough topsoil accumulates to let seeds germinate and grow, putting down roots which push apart the surface like tiny wedges. In cold climates, water gets underneath the bitumen and turns to ice, lifting the surface as it expands; over many summers and winters it might as well be a giant lifting the road and shaking it out like carpet. The next time you drive on a new highway bypass, look left or right at the older road that has been replaced; you'll see this fossil road slowly disappearing back into the scrub.

The asphalt surface of a modern road or highway is a thoroughly human thing. It is useful and valuable, because the transport uses we make of it are of value to us. It is violent and hard and dangerous, because humans are violent and hard and dangerous. Without workers and money to keep rolling, smoothing, painting, inspecting, scrubbing, and replacing, this surface is as ephemeral as a line drawn from point to point on a map. Asphalt roads are only as enduring as the engineers and workers—Irish or otherwise—are willing to make them.

Liam Hogan (@liamvhogan) is a student urban planner and is fascinated by public transport in Australian cities.

  1. Peter Norton, Fighting Traffic, MIT Press 2008.
  2. Alan Weisman, The World Without Us, Thomas Dunne Books, 2007.
Near Hopetoun, western Victoria. Image by Misho Baranovic. For more of Misho's work, see mishobaranovic.com.

Near Hopetoun, western Victoria. Image by Misho Baranovic. For more of Misho's work, see mishobaranovic.com.