Induced demand and why adding lanes doesn't fix traffic jams

Building more lanes to fix traffic is like trying to lose weight by buying a bigger belt. It sounds logical until you realize you’ve just made more room for the problem to expand.

This is "induced demand." The moment you pave a shiny new lane, people who were taking the train or staying home think the coast is clear. They flood the tarmac, and soon you’re back to a crawl—just with more lanes of gridlock.

Roads aren't just pipes; they're magnets. The more space you provide, the more cars appear to fill it.

Wait, if roads are magnets, does shrinking them actually fix the jam?

Spot on. It’s a phenomenon called "disappearing traffic." When you take a lane away, people don't just sit there fuming in a smaller space; they adapt.

Some start carpooling, others shift their commute times, and some finally realize the train is actually faster. The "magnet" loses its pull.

It sounds like madness to a planner with a ruler, but by making driving slightly more annoying, you nudge the city into a flow that actually moves.

So where do those cars actually go? They can't just vanish!

They don't teleport, mate. Think of it like a leaky tap. If you fix the leak, the water doesn't "go" somewhere else—the waste just stops happening.

When driving gets tedious, people stop making "discretionary" trips. That 10 PM run for a single chocolate bar? Cancelled. That meeting that could've been an email? It actually becomes an email.

It’s called "trip evaporation." The demand doesn't just move; it shrinks because the cost—in time and frustration—finally outweighs the benefit of the journey.

But if we make driving a nightmare, doesn't that just kill the city's economy?

It’s actually the opposite. Think of your email inbox. If it’s 90% spam, you can’t find the one message that actually matters. By making it harder for the "junk" trips, you’re basically installing a spam filter for the streets.

When the person going for a bored joyride stays home, the plumber trying to fix a burst pipe can actually get to the job on time. You aren't killing the economy; you're clearing the way for the high-value work that keeps the lights on.

A healthy city isn't one where everyone is forced to drive; it's one where the asphalt is reserved for the people who truly have no other choice.

Who actually gets to decide which trips are 'essential' and which are spam?

We don’t need a bloke with a clipboard standing on the corner. The city usually does it through "congestion pricing." Think of it as a cover charge for the busiest parts of town.

If you’re a plumber heading to a $500 emergency, a $10 fee is just a tiny cost of doing business. But if you’re just driving because you’re bored, that tenner suddenly makes the couch look a lot more appealing.

It’s not about banning people; it’s about making them ask, "Is this trip actually worth the price of a pint?" Most of the time, for the junk trips, the answer is a flat no.