The Road Is An Ecological Trap: An Interview with Ben Goldfarb

Saul here. Here’s one of the abiding ironies of our society: we’ve reconfigured our living spaces for the benefit of the only entities that regularly kill us.

Think about it. In most of the urban sprawl across the planet, big predators are rare or secretive. The leopards of Mumbai hide from their human neighbors and console themselves with pigs. When Americans go out to buy groceries, they don't have to listen for the howl of wolves. But if you live in a city where you ever walk (or bike), then you experience — dozens of times a day — the need to look over your shoulder for the car that might kill you.

In building habitat for the car — the street, the parking lot, the vast arterial highway — humans have transformed the world at large, disrupting ecosystems and creating shatter zones were strange new ecologies formed. The car has created new niches while blasting apart old ones. It’s inspired new management solutions at the intersection of human and animal pathways. And above all else, car habitat is draining the natural world in a flood of blunt-force trauma and resource extraction.

And along the way, along with the banks of suburban culverts and rural right of ways, amid the fishbone mining roads are of Amazon and the countless miles of US Forest Service roads in the American Rockies — some new rough thing rolls, struggling to be born.

Welcome to Heat Death, the newsletter that always brakes for turtles. Our guest today, Ben Goldfarb, has specialized in stories of ecosystem engineers: species that remake the world around them. In his 2018 Eager: The Surprising, Secret Life of Beavers and Why They Matter, he argued that the industrious rodents are the hidden hand behind the North American landscape — a territory thrown into chaos by the depredations of the fur trade, which effectively removed the landscapes they had built along with the beavers themselves.

In today's entry, Asher sits down with science journalist Ben Goldfarb to discuss his new book  Crossings: How Road Ecology is Shaping the Future of Our Planet — a story of ecosystem engineering on an even vaster (and more terrible) scale.

In this wide-ranging interview, they discuss how wildlife has adapted — or not — to the open roads; the surprisingly mainstream position of wildlife crossings; why green transit is as bad for animals as the internal combustion kind; and what life after cars might look like.

It’s Heat Death. Stay with us.

Asher: I loved the book. It made me deeply unhappy and upset.

Ben Goldfarb: [Laughs.] Well, I guess that's the reaction I was hoping to elicit. It's funny: My book Eager was very upbeat, about this cool, fun rodent [Beavers] that was saving the world. And I spent the next four years immersed in the land of flattened toads. So, yeah, I definitely have some misgivings about what a downer it is.

What got you interested in road ecology? And then what started you on the road, if you will, to making this your next project after Eager?

The origins of this book came in 2013. I was right at the outset of my journalistic career. And I was on this big reporting trip in the Northern Rockies — Alberta, British Columbia, Wyoming, Montana — writing about habitat connectivity, which is something that I studied in grad school, and was just fascinated by.

And I ended up taking a tour of wildlife crossings on Highway 93, in Montana, just North of Missoula. And I tell this story in the book, but I went out with this guy, Marcel Huijser, who’s one of the deans of road ecology. And we went up on top of a wildlife overpass on the Flathead Reservation, which is the land of the Confederated Salish and Kootenai Tribes. I was just so totally enchanted by being on top of this wildlife overpass — I was just captivated by the idea of infrastructure as a form of empathy for other species.  But I'm also fascinated by the the great imaginative challenge of building wildlife crossings. How do you see the world through the eyes of a grizzly bear or an elk or a marten? Or any animal? It seems like there's a fascinating technical challenge there. And how do you take the road, this fundamentally alien structure to other species, and create some kind of passage that makes that road surmountable?

It just struck me as this profound act of interspecies imagination and empathy. And that was what got me fired up. That was where the book came from.

So what is road ecology, then?

Road ecology is basically the study of how our transportation infrastructure shapes the natural world. It’s at once narrowly focused on the impact that roads have on non-human organisms. But it's also an incredibly broad field, right? The impacts of those roads are unbelievably vast and diverse.

There's obviously the road kill, the carcasses you see by the side of the highway. But there's also this truncation of migration routes — traffic forms this moving fence that prevents animals from getting where they need to be. There’s the sonic impact of roads — road noise pollution is this profound form of ecological disruption that's impacting everything from songbirds to frogs to grasshoppers.

You've got the fact that roads and our cars are just hemorrhaging zinc and cadmium, and microplastics, and tire particles — it's an unbelievable, incredibly deleterious chemical cocktail that's just leaching into the environment all the time.

And the biggest road connection is almost tough to fathom — just the ways in which roads shape landscapes. The way that their impacts transcend themselves, right? Before you can cut down an old-growth forest, you need a logging road network to get the trees out. Before you can poach an elephant, you need some kind of transportation infrastructure to get the ivory to market. So, I mean, there's the impact of the road itself, but there's also the huge landscape-scale changes that roads facilitate. I think that's part of road ecology, too.

One of the things that I was really struck by in the book is the way that you depict roads as an almost digestive entity: they go in, and then the landscape starts bleeding out back along them into the larger network. Roads crack the landscape open, in a way.

I should’ve used that metaphor! I mean, one chapter of the book is about road ecology in Brazil. The Amazon is case in point for what you're talking about: there’s something like 100,000 miles of illegal logging roads in the Amazon that have really made the supplanting of rainforests with cattle pasture and soybean fields possible.

The classic Amazonian road pattern — that you see in other places as well — is what's known as the fishbone pattern of road construction, where there's one main highway that gets punched through — in this case, by the Brazilian government, who built a bunch of main Amazonian highways in the 1960s and ’70s. And then those highways spawned this whole network of feeder roads that are often unauthorized or illegal; they're the ribs of the fish moving off the spine, up into the forest. And everywhere that those little fish ribs penetrate, deforestation increases manyfold. So, yeah, roads are kind of these these lines of penetration that facilitate all other industrial activities.

You talk a lot about fragmentation — things that are trying to cross roads and finding that the roads have these barriers, or are the barrier themselves. I was chatting with someone about the book recently and the thing it brought to mind was the idea that ever interstate highway is a continent-wide table saw that's just going all the time.

[Laughs.] Right.

Can you talk about some of the different ways that wildlife try and deal with roads successfully or unsuccessfully?

I love thinking about the answer to that question. Because animals do have really, really diverse responses to roads, which cause problems in different ways, right?

There's a great scientific paper that classifies animals into this spectrum of road responses. On one end of the spectrum, you've got what researchers refer to as non-responders, which are animals that will blithely wander into traffic, no matter how many cars are going by. And those are very often amphibians and reptiles — wonderful, wonderful organisms, of course, but maybe not as perceptive as a raccoon would be. And those animals just go hopping in traffic, often on spring migrations, and they get flattened en masse. So there it's really roadkill that causes this catastrophic population declines.

And then on the other end of the spectrum, you've got what researchers refer to as avoiders, which are animals that really stay away from roads, even when traffic is very, very low. Grizzly bears are the classic road avoiders. There have been studies showing that 10 cars an hour, which is basically one car every six minutes — which is an incredibly low traffic rate! — is enough to prevent a grizzly bear from crossing a road. So the result is genetic isolation, where bears aren't finding other bears, they're unable to reproduce as a result, and become genetically fragmented and inbred over time.

So I find that fascinating, because you have these two polar opposite responses, right? You've got animals that just go wandering into traffic no matter what, then you’ve got animals that avoid the road altogether. And yet, both of those responses are incredibly deleterious in their own ways. So just returning again to that notion of ecological empathy or interspecies imagination. I think it's really important that we understand how different animals perceive the roads, because it potentially calls for different solutions.

There’s also the third way, which is the cautious acceptance of the road. White-tailed deer obviously are somewhat cognizant of the road dangers, but also the road habitat that stretches and spider webs through the whole country is really good for them. So they make what seems to be a measured trade off: there’s the possibility of getting hit by a car, but the road margin is a good place for them to be.

Can you talk a little bit about some of the other animals that try and make a living, even if it's precarious one, alongside the road?

Yeah, that's a great point. Certainly one thing that I was really cognizant of while writing this book is that, yes, roads are generally this profound force of ecological disruption, but they're also novel ecosystems, right? And every ecosystem has its beneficiaries. Deer are a great example because, as the Interstate Highway system expanded suburbia into the American hinterlands, that process of suburbanization ended up creating great habitat for whitetail deer in the form of all of these little edge habitats, where backyards bumped into little oak thickets and whatnot.

Obviously, scavengers are classic road beneficiaries, right? We’re seeing populations of black vultures who basically expand their range along highways, which are just these linear carcass trails for them.

And then pollinators are another great example as well. We basically turned the entire American Midwest into corn and soy monocultures. Some of the last remnant strips of native prairie are these roadside right of ways, that are collectively this huge category of public land that doesn't get planted and converted to cropland.

But as you alluded to, there is this trade-off: the road is an incredibly dangerous place to live. Millions of migrating monarch butterflies get hit by cars, even as they're using roadside habitats to complete their migration. Golden eagles get hit all the time: they’re laden with these big belly-fulls of roadkill venison, and it takes them a while to take off. So there is this trade-off. Certainly, in some cases, the road can probably be in an ecological trap: it entices animals with the promises of carrion or nectar or some other resource, and then it kills them.

Well, mortality is the shaping hand of evolution in some ways, right? So, are there examples of ways that roads have definably altered evolutionary trajectories of animals in ways that we can see not just in behavior, but also down to morphology?

Yeah! It’s kind of mind blowing to think that this selective pressure has been acting for basically a century. Which is obviously a blink of an eye in evolutionary terms. There’s definitely been an evolutionary impact. The classic example of that is the story of cliff swallows, this bird that frequently plaster their mud nests on highway overpasses and bridges. They're making a living in and around traffic and those kinds of infrastructural spaces, right? We have really helped them expand their range. And they're a rare species that's really benefited from our infrastructure in some ways, but it has come with this evolutionary trade off.

Charles Brown, a swallow researcher, showed a few years ago that swallows' wings were becoming shorter over time. The reason for that is that long wings are good for straight-line flying over long distance, while having short wings is better for agile flying in close quarters. And so if you're a swallow living under a highway overpass, and you're constantly at risk of being hit by 18 wheelers, it behooves you to have shorter wings to make those tighter rolls and turns and pirouettes to avoid traffic.

So the long-wing swallows have been culled from the population by unnatural selection. And the swallows in Nebraska have evolved shorter wings as a result.

Can you talk a little bit about the different ways that people have tried to get around this problem by creating crossings? In the book you discuss some attempts that worked really well, and some that have fallen flat on their face in pretty embarrassing ways.

There have been some embarrassing failures — famously, a toad tunnel that was built in Davis, California, and didn't get really used by any toads, because it was just much too narrow. And it was made a mockery of by Stephen Colbert, back when he was with The Daily Show.

To me, the big picture is that well-built crossings do work really well. And I mean, there are just a bunch of great examples all over the country and really the world. Western states — like Wyoming, Montana, Colorado — historically have been the leaders in building underpasses, mostly, for mule deer and elk. And the reason is that in Western states, you have these big migratory herds of ungulates that cross roads in very predictable places and form these big collision hotspots that are relatively easy to address with a broad highway underpass, or a big box culvert.

But one of the cool things that happened in the last 10 to 15 years or so, is that I think the transportation departments have expanded their focus. It used to be that they would devote all of their attention to preventing collisions with big animals, like deer and elk, that were dangerous for drivers, right? And the construction of crossings and roadside fences was really driven by this concern for human safety, you know, not the animals themselves. They were just trying to prevent collisions with a moose that would kill you.

Whereas in the last decade, I would say, transportation departments are broadening their view to include animals like amphibians and reptiles, which obviously, aren't a human safety issue. Nobody's ever died hitting a garter snake. But roads are this huge population-level threat to amphibians and reptiles, as we've talked about. Europe was the pioneer here. They built toad tunnels dating back to the 1960s in many countries. And over time, that movement has   expanded to include North America. Now, you see states like Vermont building these wonderful amphibian passages which — they're not these grandiose structures. They can be a little culvert that's a couple of feet wide; you would drive over without ever knowing who it was there. And yet, a well-placed, well-designed amphibian tunnel is highly effective. So think that's been the history of wildlife crossings, in some ways, is moving the obvious victim in many car crashes to the more subtle ones.

You talk also about some remarkably elaborate wildlife crossings that are being pioneered now, which are trying to figure out how to coax an animal over the road.

I think that the field is expanding in that direction. In California right now, the biggest wildlife overpass in the country is currently being built to connect a population of inbred cougars in the Santa Monica Mountains with genetic reinforcements.

And there, the overpass has to span U.S. 101, which is the busiest freeway in the country. And that's 10 lanes of traffic plus shoulder — just a massive, massive freeway. That creates all kinds of problems, right? I mean, there's the headlights, there's the noise pollution, and there are these stimuli billowing off the highway and potentially preventing animals from wanting to use that crossing.

So there, the design challenge has really been: How do you create an ecosystem atop of a bridge that's going to be enticing enough for an animal to want to cross 10 lanes of incredibly busy traffic? And that's through the use of vegetation screens, and berms, and other features that block some of that noise and light pollution. And it's also through the inclusion of real habitat elements — shrubbery and trees, and thickets, and little pools for amphibians and all kinds of topography and habitat features that animals might find appealing.

I think that's really a departure in some ways from the early history of ecology, which was basically: OK, build a structure and throw some dirt on top of it, some gravel, maybe plant a shrub or two and then basically call it good. But there is evidence that animals will avoid really bright or noisy crossings.

So I think that the more we learn about how creatures interact with these structures, the more we realize that, hey, we really need to put more attention and care into making these things true ecosystems in some ways. Because a bunch of bare dirt might not cut it.

When we're talking about infrastructure, one of the things that's happening right now is a huge amount of building out that's happening all over the world — you quote somebody as calling it the 'infrastructure tsunami.' Even though a lot of our road systems in America are not well maintained, obviously more and more are being put in in all of these different countries.

Can you talk a little bit about the building out that's happening, and the degree to which any of those roads are taking into account these questions about things like animal mortality and ecosystem fragmentation?

Yeah. Definitely. We're gonna get something like 50 million new miles of roads on this planet by 2050. And the vast majority of those roads are going to be built in developing countries, which also happens to be where most of the planet’s remaining intact habitat is located.

And I obviously benefit from infrastructure in all kinds of ways, as all Americans do. I think there's no denying that highways and rail lines, fiber optic cables, shipping ports, and all of the infrastructure that's part of the tsunami, is ultimately going to be beneficial in a lot of ways for human wellbeing. Right? I mean there are all kinds of advantages: say you're a farmer in Sub-Saharan Africa — if you have a good highway that connects you to markets, you can access education and health care and all of the other services that we take largely for granted in the United States.

So the infrastructure tsunami is from a human welfare standpoint, probably a pretty positive thing. Right? But it also risks inflicting profound damage on biodiversity. I mean there are more potentially catastrophic projects than you could possibly name being planned for the Mongolian Steppes and Indonesian Borneo and Kenya, where mostly Chinese investors are building infrastructure at just a mind-blowing rate just off of national parks.

Basically name a species of charismatic megafauna, from African elephants to Asiatic cheetahs to gorillas, and this new wave of infrastructure is probably the greatest threat to its survival in a lot of ways. So it's really incumbent that if this building is going to happen, to do it right. And maybe that means rerouting highways to spare intact core habitats. Maybe it means building wildlife passages when a highway truly, truly can't be prevented. You can at least make it a little bit less catastrophic.

And that's happening in a lot of places! When I started working on this book, my attitude was basically like: Well, there are all of these great road ecologists in North America and Europe, and surely they are going to Myanmar and Malaysia and telling those transportation agencies and governments how to do things right.

But actually, there's so much innovation in the developing world — because we're stuck with our calcified, difficult-to-improve interstate system, whereas they're still creating infrastructure and as a result they can be more creative from the get-go.

So in India, for example, there's this huge stretch of elevated freeway — something like 15 or 20 miles — going through this tiger reserve, where the highway is actually up on pillars above the rainforest, and animals can  move below with no problem. And that’s more thoughtful and innovative and radical in its own way than anything in the United States, right? I think the exchange of knowledge is much more bi-directional.

That was one of my favorite little grace notes in the book: the person you spoke to who was like, Oh, they just lifted the road up. You can do that.

Another aspect of infrastructure, obviously, is the race to try and put AI vehicles onto roads, and you have a really interesting chapter about some the potential opportunities, as well as the potential threats.

Yeah. Obviously, autonomous vehicles have experienced all kinds of hiccups. Even a few years ago, the industry was talking about our vehicle fleet being largely autonomous by 2030. And certainly, that's not going to happen. But self-driving cars are already on the roads, and their share of the market is only going to increase.

And I think that, from one perspective, that's probably not the worst thing for biodiversity, right? I mean, we humans are incredibly fallible. We have all kinds of blind spots and attentional biases. I mean, our vision is not very acute. Certainly there's a world in which autonomous vehicles are much better at detecting and avoiding large animals than we are. You can imagine a world in which deer-vehicle collisions — which happen constantly, all over the country — become almost a thing of the past.

So that's the good news.

I hear a "But" coming.

The bad news is, basically everything else, right? [Laughs.] The companies that are building autonomous vehicles, as far as I can tell, are not particularly interested in wildlife. And, as a result, basically their sensor technology is only equipped to detect animals that are as large as a human. So if the animal is the size of a small person, an autonomous car is likely to avoid it. And if it's anything smaller, it won't, right? So, you and I drive around, presumably braking for squirrels and snakes, but an autonomous car is not going to do that. You would have to imagine a world in which large animal collisions go down and small animal collisions remain static or even increase, you know?

The bigger issue, in some ways, is that it's almost certain that the combination of autonomy and electrification is going to dramatically increase total vehicle miles traveled over time. If you don't have to drive, and your car is this great little mobile work or entertainment station, where you can hop on Zoom or watch Netflix or whatever, then commuting is no longer such a burden, right? You could theoretically live further from your workplace and commute more often and longer distances. The inconvenience and displeasure of commuting has sort of constrained the total miles traveled by our vehicle fleet. But autonomy could shatter that. Most projections basically say that autonomous cars are going to dramatically increase [vehicle miles traveled].

So you can easily imagine this moving traffic basically becoming this impenetrable brick wall, as automobility and traffic rates just dramatically increase due to autonomy.

Right. Theoretically, the thing about the suburbs is that you have to be at least a little bit close to the city, because you have to be awake to drive there. But what if you don’t? What if we develop these municipal footprints out further and further, rather than actually consolidating?

Yeah. I think that's exactly right. We've been talking about the movement of human beings, but the first thing that autonomy is going to transform is shipment of goods, right? The first frontier, I think, of self-driving cars is ultimately going to be self-driving trucks. You can imagine warehouses pushing further and further out into the hinterlands because there's no reason a self-driving truck couldn't be active all night long, right? A human driver needs to take a break once in a while. Darkness, which is this reprieve for animals right now, could become just as dangerous. And you could imagine huge fleets of trucks, going from warehouse to city shipping all of our plastic crack to us in urban areas.

That's definitely a plausible and concerning future, one in which our civilization is more sprawling and less consolidated.

It seems like once the roads go in, human management of landscapes then has to increase a lot to account for the impact of the road. You have a road, you have to manage a lot to deal with the level of disruption that the road brings.

Is there a willingness in policy circles to do that really intensive road mitigation work?  

It's a good question.

The irony there is that early on in the history of the public lands management agencies — the Park Service, the Forest Service, the Bureau of Land Management — the idea was that roads are going to make our lives much easier: we'll put roads in, and then we can properly steward these lands that God has given us. We can cut down beetle-infested trees when infestations strike and we can properly manage the elk herd, the trout. Roads were how we could steward nature in this very heavy-handed way. But as you said, ultimately, the roads create many more problems than they solve.

But that mindset, that we need the road system to manage nature — I think that’s a really persistent mindset. I think you probably see that most powerfully in the world of wildfires. The Forest Service is the largest road manager in the world, which is a mind-blowing fact. And I think that a lot of the rationale for maintaining this huge road network is that — hey, we can get in there and fight wildfires as soon as they break out. And the roads themselves, they often  function as fire breaks as well. There's no flammable material on the road. There are no trees!

So there's this attitude that road networks are essential for fighting fire. But the great irony there is that roads are also the catalyst for wildfire. You’ve got a trailer throwing off sparks into brush or a hot muffler in tall grass, or just campers backpacking along the forest road, and they light a campfire, and it gets out of control. There are all kinds of studies basically showing that wildfire ignitions are much, much higher along road networks, because, again, roads lead people into the forest, and people start fires.

So in some ways that fire tension epitomizes what you're talking about, which is that we still have this idea that we need roads to conduct proper management of nature, even though roads are the forces that are creating some of those issuesin the first place.

You spent four years working on this — traveling around, reporting, really taking the temperature of the field. What do you think the future looks like here?

I mean, certainly the future includes many, many, many more wildlife crossing structures. There's a big pot of money that was allocated in the 2021 Infrastructure Act devoted to wildlife crossings. Right now, as we speak, the federal government is about to decide how that money is divvied up and allocated. Basically, every state in the country is going to have some proposal for how they would spend this federal grant money. So there's no question that wildlife crossings, which have historically been the very marginal pet projects of crackpot engineers, are going to become just the way that we do business. Every time you add a lane to a highway it's going to include a couple of wildlife underpasses. We’re already seeing that happening. I think that is undoubtedly going to increase.

So, theoretically, we're going to have more permeable highways to animals. That's good. But — I think the other trends are probably pretty bad. We're seeing more vehicle miles traveled now.

Even after COVID?

COVID was like a brief hiccup where traffic declined only momentarily and then came   roaring back by the summer of 2020. In some ways, Covid actually accelerated a lot of the negative trends that we were talking about earlier —  it basically encouraged remote work. People wanted to be close to nature, that's all good. But as a result, they move out into these historically intact habitats, so you see this increased sprawl, in many cases new development, that land trusts and other environmental groups are powerless to stop.

So, yeah — [chuckles cynically] I think that the future is going to include more driving and certainly more road-facilitated development in places that had been undeveloped.

I think one of the interesting tensions that I addressed more head-on in the book is just the ways in which the electrification of vehicles is going to accelerate that as well. I keep using the word irony, but there's so many ironies in the world of transportation. But there's just been so much policy focus on encouraging the electrification of our vehicle fleet for the sake of climate change, but obviously, electric vehicles do nothing good for wildlife. And, in fact, you could imagine a scenario in which they do a lot of bad, right? By making it cheaper to drive, because you don’t have to fill the gas tank.

You could imagine a world in which EVs, like self-driving cars, dramatically increase traffic. So a future in which our vehicle fleet is electrified is probably good for the climate ultimately, but does a whole lot of nothing, I think, for wildlife.

Well, you opened the book with a really interesting exploration of how cars took over in the first place and how that was not inevitable. There was a lot of work done by the automobile interests to make that happen, in the face of strong resistance by people who were expressing pretty much the same concerns that are being addressed today.

Basically, the thought seems to be that cars are a problem. And if we just electrify them, they won't be a problem. But an electric car is still a car.

What you put your finger on is the fact that today we view cars as this inevitable part of our urban landscape. We live in a world designed for cars, dominated by cars, because the car is a superior technology whose victory was inevitable.

But that's not the case at all. It’s incredible to read about this ferocious backlash to cars that erupted as the first Model Ts began to overrun American cities in the early 1900s. People hated cars, right? Cars were unbelievably dangerous. They killed children at astronomic rates. There were constant safety parades held in American cities where people would get out and protest the way in which cars had taken over their lives and their urban habitats.

Eventually that barrage of car industry publicity negated all of that backlash. [Editor’s note — as well as an enormous public investment in roads, which Goldfarb also discusses in the book.]   Cars were increasingly perceived as good and beneficial and unavoidable. And they just took over, you know? And then for about 100 years, the backlash was essentially non-existent.

I think that what we're seeing today is a bit of the return of the backlash. My favorite podcast is The War on Cars. It's a great podcast about urban walkability and bikeability and livability. You see Gen-Z  rejecting cars, right? Teen driving rates are way down — certainly younger millennials drive a lot less than their boomer parents did. Some American cities — and definitely a lot of European cities — have taken measures to kick cars out of urban cores and return pedestrianism to its proper place in the community fabrics.

Those are all good things, certainly. The challenge from the road ecology standpoint is that a lot of that urban livability stuff is not really where the wildlife conflicts are. It's great to create cities that don't really require cars. But that's not going to do a whole lot of good for an elk migration in Wyoming, right? It’s hard to foresee the technology that is going to dethrone the car across the vast majority of American landscapes, if that makes sense.

Of course. The infrastructure is so built out at this point. But I’m curious — do we have a sense of how railways impacted the landscapes they moved through?  

It’s funny, there’s a little subfield of rail ecology. Unfortunately, the takeaway from a lot of the studies that have been done on railroads and wildlife is that they're really detrimental. In some cases they actually have higher roadkill rates than highways do — maybe on a per-vehicle basis, I guess — because trains can't brake, obviously, unlike drivers. And they also become these ecological traps, which, of course, happens on roads as well. Freight rail is used to ship huge volumes of grain and other food products that inevitably spill, and the rail line turns into a trap. It’s a huge issue in Banff National Park, where grizzly bears get killed frequently foraging along along the track.

So, what then, is the ideal future? To bring the conversation back around to the imaginative challenge of building a world where animals are flowing around and under and over roads — instead of just across them into their deaths — what should people should be working toward?

It's funny — it's a great question, and I don't really have a good answer. The best-case scenario, I think, involves society-wide rejection of automobility. The best-case scenario is that we win the war on cars. But that just feels so far-fetched. I mean, maybe if I lived in Seattle, that would feel possible, but now I live in rural Colorado where you basically have to have a car. And I'm stuck using it if I want to get basically anywhere outside of the little town I live in.

So, you know, Asher, I just don't have a good answer for you. Because frequently, it's funny, working on the book, I felt like I was collaborating with cars in some ways. Or at least not rejecting them soundly enough, right? I mean, in some ways, it's wonderful to talk about wildlife passages, but that's also a capitulation to the dominance of the car. Right? A wildlife crossing is basically an admission that the road and the traffic on the road is always going to be a problem, and we're basically stuck with it. So in devoting huge portions of this book to wildlife crossings, there were certainly times when I felt like, I was not being radical enough, or I was letting the cars’ dominance be a self-fulfilling prophecy — if you don't truly challenge it, the car is going to remain our dominant mode of transportation.

So, yeah, I feel like in some ways that maybe the book doesn't hit upon an ideal enough solution. I don't know. I mean, what do you think the ideal solution is or the ideal world? What does the ideal world look like to you?

That was why I was asking you! I think it's tough. There’s ideal world that is totally utopian, and the ideal world that feels difficult to imagine, but potentially reachable. The utopian world is one where transit is bundled and consolidated into a couple of main transit corridors, with the urban landscape drawn back along them. And a ton of wildlife crossings along those major transit corridors to try and mitigate the fact of their existence.  

But to me, the even more imaginable ideal thing is that every new road that’s built is raised, like the ones going through tiger habitat in India. And if that means that it's a little bit more difficult and a little bit more dangerous, that feels like a reasonable trade-off to me ecologically.

But I don’t know. Because I also, of course, drive a lot too. Like you, I’m out all of the time. And I don't feel great about it. I wish that there was more muscle behind finding infrastructural solutions, even if those maintain the dominance of cars. But also, I just don't know how you get rid of them at this point. Beyond broad and catastrophic societal collapse, which would do it pretty quickly.  

[Laughs]  I like your centralized transit corridor idea. I think that hits upon the fact that there's so much redundancy in our transportation system, right? Not only can you get from point A to point B anywhere in the country, you can get from point A to point B in a million different ways, because we have this incredibly — nonsensically! — elaborate and densely woven road network. And you could imagine a world in which a lot of that redundancy is stripped out of the system.

In the book I talked about the decommissioning of forest service roads — the notion that only a tiny fraction of forest road networks are really necessary from a management perspective, and the rest could be returned to nature pretty easily. Although, of course, that's not happening yet.

We also have a chapter about the destruction of urban freeways in some cases. Again, the total number of miles of urban freeway that have been destroyed is probably in the double digits, right? So, it's not like this is happening on any massive scale. But I do think the fact that roads have been destroyed proves that they are not necessarily immutable features of the landscape. They're things that we made, and they're also things that we could theoretically unmake.

So I like your transit corridor idea, because I think it hints at the fact that roads are not necessarily permanent features. They can be destroyed, if we have the will to contract the redundant network we've built.

Is there anything that you wish that you dug into? As befits a book about roads, it's a really wide-ranging survey of the topic. Anything that got cut for time, or interesting little byways and alleys that you wish you'd been able to go down?

Man. Yeah. There’s so many. I think that the final draft of the book was about 30,000 words shorter than the first draft. So a lot ended up on the cutting room floor.

You touched upon it with your question about train ecology. In some ways, road ecology is a subfield of transportation ecology, and there are all of these other little subfields of transportation ecology that I am fascinated by, and don't really explore in the book. I mean, marine road ecology is just unbelievably complex and interesting. Vessel strikes and ship noise are some of the most profound negative things we do to marine mammals and all kinds of other species.

There's a great article in New York Times Magazine about Atlantic sturgeon and the fact that a huge proportion of sturgeon deaths are caused by ship propellers. You'd never think about vehicle collisions being an existential threat to a fish, right? But, in fact, they are. So I would have loved to have explored marine ecology. There's also a whole field of aviation ecology involving the mitigation of airplane-bird collisions, mostly around airports — a fascinating history of airports trying to solve bird strikes.

In some ways, the book does feel impossibly broad at times, but in some ways, I wish it had been even broader, to encompass more forms of transportation.

I think it’s honestly an incredible accomplishment and you should be very proud of it. Ben, thanks so much for coming on.

My pleasure.

Ben Goldfarb is an environmental journalist whose work has appeared in Biographic, Hakai, and many other places. His new book, Crossings, gets our highest recommendation and is available here, or wherever finer books are sold.

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