We’ve all seen the pictures of professional hockey players giving up the battle with Toronto traffic and walking to the arena. To put it kindly, Toronto traffic does not work and it is getting worse. By comparison, Hanoi traffic should not work. Using any traditional urban planning metric, the city of 8.8 million people with 7.6 million registered vehicles is a rolling contradiction: motorbikes, scooters, buses, taxis, and trucks all competing for narrow streets, with pedestrians threading themselves into the mix. Add bicycles and electric motorbikes and the task of traffic management seems even more daunting. There are few stop signs, traffic lights are more like suggestions, and lane markings — when they exist — serve as faint decoration.
And yet, it works. Even well. The city moves. Traffic rarely freezes for long, and somehow everyone seems to know what everyone else will do next. Compare this to Toronto, where gridlock is a civic ritual. How is this possible? The answer lies in a cocktail of physics, culture, and collective intuition.
1. Continuous Flow vs. Stop-and-Go
In Toronto, intersections are controlled by an endless sequence of lights, signs, and signals that force vehicles into stop-and-go patterns. From a physics perspective, every stop is an energy sink: momentum is lost, fuel efficiency drops, and congestion builds as queues form behind each point of control.
Hanoi’s system minimizes full stops. Scooters and bikes bleed speed rather than halt entirely. Traffic lights are fewer and far between, and when there is a red light, you’ll often see a constant trickle of turning vehicles navigating gaps. This creates a form of laminar flow — continuous movement, even at low speeds, prevents bottlenecks from locking up the network. Dr. Baher Abdulhai from the University of Toronto is working on this problem, among others.
A renowned civil engineer and expert in Intelligent Transportation Systems (ITS), Dr. Abdulhai leads the ITS Centre and the iCity Centre at U of T. His work includes modeling and optimizing traffic networks using AI, which offers a compelling angle on dynamic systems like Hanoi’s complex traffic flow.
Lesson for Toronto: Replace some full-stop intersections with continuous-flow designs such as roundabouts, dedicated turning pockets, or pedestrian-priority crossings that slow traffic but don’t stop it entirely.
2. The Physics of Small Units
In Hanoi, the dominant vehicle is the scooter. Scooters have a far smaller footprint than cars — physically and in terms of reaction time. They can accelerate and decelerate quickly, occupy gaps that cars can’t, and change lanes (loosely defined) without disrupting overall flow.
From a particle-physics analogy, scooters are like smaller molecules in a fluid: they have more freedom of movement, making the “traffic fluid” less viscous. Toronto’s traffic, dominated by large cars and SUVs, is more like a slurry of big, slow-moving particles.
Lesson for Toronto: Encourage smaller, more agile vehicles in dense areas — not just scooters, but microcars, cargo bikes, and e-bikes. The more varied the scale of mobility, the more options traffic has to self-organize.
3. Decentralized Decision-Making
Toronto traffic is centralized — every driver defers to rules, signals, and signs. The expectation is that the system tells you what to do. In Hanoi, traffic is decentralized: every driver makes micro-decisions based on immediate context.
This creates a self-organizing system similar to flocking behavior in birds or schools of fish. Each rider follows three principles:
- Maintain your own path and speed as much as possible.
- Avoid collisions at all costs.
- Be predictable in small movements.
Because everyone expects everyone else to be making autonomous decisions, reactions are faster and more adaptive. In Toronto, any deviation from the prescribed order (a sudden lane change, a driver running a light) is an anomaly — and anomalies create chaos.
Lesson for Toronto: Over-regulation can sometimes make a system less adaptive. Give intersections “shared space” design principles where drivers, cyclists, and pedestrians negotiate movement by sight and interaction rather than by rigid control.
4. Human Density Awareness
Hanoi’s drivers operate in close quarters. The average following distance is measured in inches, not meters. This would be terrifying in Toronto, but in Hanoi, it’s the norm. The physics is simple: less empty space means more vehicles can occupy the same stretch of road without increasing congestion.
The cultural component is trust: riders expect competence from others and assume that the person next to them does not want to crash. Toronto’s driving culture defaults to distrust, so drivers maintain large gaps, reducing road capacity and amplifying slowdowns.
Lesson for Toronto: Narrower lanes and slower speed limits in urban cores can increase density without sacrificing safety, as they encourage closer, steadier travel.
5. Friction as a Friend
Urban planners in North America often aim to eliminate “friction” in traffic — meaning anything that slows movement. Hanoi embraces low-level friction: uneven road surfaces, parked scooters, roadside vendors, and wandering pedestrians. These constant micro-obstacles slow the average speed, but also prevent the catastrophic collisions that happen at high speeds.
It’s a paradox: slightly slower traffic is more fluid because it remains safe enough to stay in motion.
Lesson for Toronto: Slow traffic in city centers not by banning cars outright, but by designing streets that naturally keep speeds low while maintaining flow — think shared streets, curbside vending, and more pedestrian mixing.
6. Noise as a Signaling System
The honk in Hanoi is not an expression of rage; it’s a form of echolocation. Riders tap their horns to signal position, intention, or awareness. A short beep says, “I’m passing.” A double tap says, “Don’t drift left.” This constant audio chatter allows riders to anticipate movement without relying on mirrors or blind-spot checks.
Toronto drivers honk as a last resort — by the time they do, it’s already too late to adjust.
Lesson for Toronto: While transplanting honking culture wholesale would be a disaster, the principle is valuable: more signaling, earlier signaling, and normalizing non-hostile communication between drivers could reduce surprise maneuvers.
7. Flexible Road Hierarchy
Toronto streets are strictly zoned: arterial, collector, residential, each with fixed speed limits and rules. In Hanoi, the functional hierarchy changes in real time. A narrow alley might act as a primary route during rush hour. A sidewalk might temporarily become a scooter lane. This flexibility means that when one route is blocked, the system quickly redistributes flow without needing official detours.
From a network theory standpoint, Hanoi’s traffic grid is scale-free — multiple alternate paths exist, and users constantly discover and exploit them. Toronto’s is rigid and more easily paralyzed.
Lesson for Toronto: Encourage permeable street networks and allow for adaptive use of space. Build redundancy into the road system so traffic can re-route dynamically.
8. Cultural Calibration
Finally, physics alone doesn’t explain it — culture does. Hanoi’s traffic works because people enter it with the expectation that chaos is normal, and everyone’s job is to keep moving without harm. There’s a social contract to merge, yield, and weave with minimal fuss.
In Toronto, driving is competitive: merging is seen as weakness, yielding is an inconvenience, and “winning” your lane is a small personal victory. This fosters antagonism, which reduces cooperation and amplifies gridlock.
Lesson for Toronto: Culture change is slow, but urban design can encourage it. Spaces that require cooperation — like shared streets and bike-priority zones — can normalize more collaborative driving behavior over time.
The Takeaway for Urban Planners
Hanoi’s traffic isn’t a miracle. It’s the product of continuous flow, small vehicle dominance, decentralized decision-making, and a culture of trust — all underpinned by physics principles that cities like Toronto could adopt. It’s also true that there are more accidents in Hanoi, largely attributable to the dominance of motorbikes which account for 70% of accidents.
Ironically, the key lesson is that less rigid control can lead to more order. In traffic as in fluid dynamics, systems with more adaptive components and fewer bottlenecks can maintain flow more efficiently than systems ruled by rigid, centralized controls. You can get stuck in Toronto traffic at a single intersection for 45 minutes or longer.
One of the main complaints about Toronto is its traffic. Taking some lessons from Hanoi, despite its flaws, would help. Thanks to the rigidity of Toronto municipal politics, however, as anyone who has grappled with zoning knows all too well, this is going to be a challenge. With local experts like Dr. Abdulhai from the University of Toronto, though there is hope.
