When One More Lane Isn’t Enough… So You Dig a Highway Underneath
Digging a Highway Under the 401: The Most Car-Brained Idea Yet
“One more lane, bro—just one more lane."
This meme perfectly encapsulates 70 years of North American highway expansions. Stuck in traffic? Just add another lane—problem solved, right?
This car-brained logic has dominated traffic engineering in North America since the 1950s, when the Interstate Highway System was born. The prevailing wisdom? More traffic means more highway lanes, which means fewer red taillights in front of you.
But take a look at I-5 in Santa Ana. Compare the same vantage point over 75 years, and you’ll see a small, narrow freeway that has morphed into a sprawling 10-lane highway with elevated HOV lanes—yet traffic still clogs the road.
Obviously, this continent and its urbanized areas have grown exponentially since the inception of the interstate, so it makes sense that highways would expand as well. But the problem lies in the bottleneck—both physical and metaphorical—that highway expansion creates for the growth of an economy and a region.
Take Atlanta, where “we full” has become an unofficial slogan for residents who believe the metro area has too many people and doesn’t need any more—because of "traffic." But how can an urban area be objectively full when Atlanta's metro area is 60% larger than Tokyo’s yet has 35 million fewer people?
The answer? Car dependency and highways. A staggering 76% of Atlanta’s commuters drive alone, meaning the region’s growth is constrained by how many cars can fit on a highway. When there are no viable alternatives, of course the city feels full.
A perfect example of this flawed urban design is the well-known (though slightly outdated) comparison between Atlanta and Barcelona, which highlights the inefficiencies of car-centric development.
Induced Demand is a Real Thing
Traffic engineers for the most part know and have seen that highway expansions do not work, as induced demand is very present and unrelenting. Induced demand is the idea that when more of a good or service becomes available, more people will use it.
The thought process behind expanding highways is simple. If demand stays the same and capacity increases, congestion will therefore decrease. But the reason this fails in almost every instance is that when drivers hear that a highway widening was completed, they shift their commute patterns to then use said highway, where demand is now increased and increassed capacity is then met, which results in traffic is the same as before.
Think of it another way, if you put cheese and crackers out at a party and you run out, you must assume that no one will eat more once you replenish them, which is never the case. My family used to share a 10GB phone plan, which kept our data usage low. But once we switched to an unlimited plan, we used nearly 80GB—simply because we could. Highways work the same way: when capacity increases, people drive more
Even Robert Moses, the infamous highway builder of the 20th century in NYC also knew that more highways and expansions meant more traffic.
Moses’s unprecedentedly ambitious traffic devices, together with his highly publicized promises that they would solve the traffic problem (and the easing in that problem that occured for a few months every time a new facility was opened), raised hopes; with hope, motorists dated to look again at what they were being subjected to. And when, a few months after each new facility opened, the jams began to build up again, their consciousness, newly reopened, was rubbled all the more raw. In the last two or three years of that decade, with the Triborough Bridge and the West Side Highway and the Interborough and Grand Central parkways open and congestion worse than every, there was another howl of public anguish.
The Power Broker, Page 913
Why We’re Stuck in a Car-Dependent Loop
We keep expanding highways in North America for the same reason we lack great transit: our deep dependence on cars makes it politically and socially difficult to change course. After decades of doubling down on car-centric infrastructure, a single transit line won’t be enough to reverse car dependency. Real change requires bold, systemic shifts, not incremental tweaks.
When faced with this reality, policymakers and planners often take the path of least resistance:
Path A: Expand highways and continue to fuel suburban sprawl.
Path B: Build A LOT of transit and gradually shift travel behavior and voter preferences.
So far, we’ve stuck with Path A, but the only way to break the cycle is to commit fully to Path B—not just with small one off projects, but with a true reimagining of how our transportation system move people.
A $100 Billion Highway Tunnel? Seriously?
The 401 freeway is the busiest in the world, moving 400,000 cars per day. If you assume an average car occupancy of 1.7 people, that’s 680,000 people daily—for comparison, London’s Elizabeth Line moves even more passengers per day.
Originally built in the late 1940s with just two lanes in each direction, the 401 has expanded nearly every decade and now stretches to nine lanes per direction in some areas. But instead of simply adding yet another lane, Premier Doug Ford wants to build an entirely new highway—underground.
While details are scarce, the tentative proposal suggests constructing an underground tunnel beneath the 401 between Scarborough and Mississauga, where congestion is at its worst. Beyond this, little is known.
Why Is This an Awful Idea?
Induced Demand
Even if you add lanes or tunnels, bottlenecks like local streets and exit ramps will continue to limit capacity. Unless road infrastructure is expanded across the entire regional network, congestion will persist no matter how many highways you stack on top of each other.
Cost and Project Size
The rumored cost of the project is $100 billion CAD, but if we use Seattle’s highway tunnel as a comparison, the real cost could be closer to $138 billion CAD. That’s equivalent to building 3,563 km (2,212 miles) of GO Rail expansion.
Even the most ardent highway expansion advocates would agree that this project would require additional infrastructure improvements, making the total cost even more staggering.
Remember Boston’s Big Dig? Expect similar cost overruns, delays, and logistical nightmares.
Timeline and Future-Proofing
Building this tunnel would take decades under Ontario’s regulatory framework. By the time it’s completed, emerging technologies like autonomous freight and electric vehicle infrastructure could render its benefits obsolete. Future-proofing a $100+ billion project of this scale would be nearly impossible.
There Are Already Highways
The controversial new Highway 413 (shown in green on the map above) is set to start construction soon, and Highway 407, which runs parallel just five miles north of the 401, could handle more traffic—if it weren’t a toll road. The 407 is underused precisely because it costs money, while the congested 401 is free.
Better Solutions
Build East-West Rapid Transit Options: There are very few rapid transit options connecting Mississauga and Scarborough without detouring through downtown Toronto. During rush hour, transit takes nearly two hours, more than double the time of driving. Expanding GO Rail, light rail, or BRT would provide viable alternatives to the car dependency driving congestion on the 401.
Subsidize and Incentivize Commerical Use of the 407: The 401 corridor is one of the busiest freight routes in North America, with nearly 40,000 trucks per day. Of these, 85% stay within the Greater Toronto Area (GTA), while the remainder travel to Western New York, Michigan, and Quebec.
Since the 407 is a toll road, most trucks avoid it for the free 401, worsening congestion. Research from Environmental Defence found that subsidizing truck tolls on the 407 could divert 12,000 to 21,000 trucks daily from the 401, saving at least $94 billion in the long term. (Given a NPV of $6 Billion CAD over 30 years)
Let’s Focus
The definition of insanity is doing the same thing over and expecting a different result. After 18 lanes, it should be obvious that Ontario won’t solve congestion with more lanes, less so more highways.
Let’s get serious. We need to stop doubling down on the past and start building a future that prioritizes smarter, more sustainable transportation.
“One more highway, bro—just one more highway."