Philly's Spatial Reality

Why More Car Infrastructure Is a Dead End

TL;DR: Philadelphia's streets can’t be expanded. There's simply no room to keep prioritizing them - the math doesn't work. We can move more people more safely, for less money, by investing in alternatives.

Last week I was at a zoning meeting where someone earnestly suggested that what Center City really needs is "wider streets to accommodate more traffic."

As someone with a history of bowel obstructions, I could understand the sentiment.

And Philly’s streets are indeed like my bowels: there’s too much mission-critical infrastructure in the way to just “add a lane.”

There's a fundamental reality about Philadelphia that car-centric thinking just can't overcome: we're a dense city built on a human scale. And the parts that are built for cars are way too expensive and dangerous to serve as something to emulate.

But let's take a step back and look at this objectively with some simple math about space.

The Physics of Philly's Space Problem

Let's talk pure spatial geometry for a minute:

• A parked car takes up about 180 square feet (a 9' x 20' parking space)

• A moving car at 25 mph needs about 500 square feet with safe following distance

• A single car lane can move about 1,000 people per hour (assuming 1.2 people per car)

• A 12-foot wide sidewalk can move 9,000 people per hour

• A 12-foot wide bus lane? 4,500 people per hour

• A 12-foot wide bike lane? 7,500 people per hour

This isn't liberal urbanist propaganda – it's physics. Cars are the least space-efficient way to move people through a dense city. Full stop.

The "Just One More Lane" Fallacy

“Couldn’t we just add more lanes? We’re not NEW YORK dense, and I don’t want us to be.”

Well, no, we can’t add more lanes. For two practical reasons:

First, there's literally nowhere to expand. Unless we're planning to knock down all those historic buildings that make Philly, you know, Philly, we're stuck with the street widths we have.

Second, decades of traffic research have conclusively proven that adding car capacity doesn't reduce congestion – it induces more demand. It's like digging out your shower pan to install a wider drain, but still pooping in the shower. Makes it easier for now, but there’s another, better fix. And you’ll end up stepping in it, so to speak.

Dallas, the poster child for road expansion, has spent billions widening highways and remains notorious for its awful traffic. Not because they stopped expanding too soon (as far as I’m aware, they’re still digging that grave), but because the bigger they make the drain, the more friends want to join them in the shower.

And ultimately, you just can’t get a drain big enough to accommodate all that crap.

And on the density question – while I disagree that artificially enforcing low density is good for anyone (see: housing crisis), suffice it to say that Philly’s unique status as “poorest big city in America” is enough to convince me that forcing car ownership on our residents is bad fiscal policy. It’s bad safety policy. It’s bad economic policy.

Even if we add zero new people (which would be a bad thing, because more people in the city makes the whole pie bigger, rather than taking your slice away), the present state isn’t exactly something to be envious of.

Why not let people who love cars continue to have them? But let’s make it possible to get around without them, too.

Philly By The Numbers

Let's look at our actual city:

• Population: ~1.6 million people

• Land area: ~140 square miles

• 2,525 miles of streets (averaging 30-40 feet wide)

• Registered vehicles: ~767,000

• On-street parking spaces: ~400,000

If every adult in Philadelphia owned and drove a car, we would need to devote 68% of our entire city's land area just to parking them. Not driving them – just storing these metal boxes that sit unused 95% of the time.

Thankfully, about 33% of Philadelphia households don't own cars at all. In Center City, that number jumps to nearly 50%.

But here's the kicker: we've still dedicated more space to cars than to humans in most neighborhoods. The typical Philly street gives 80% of its space to vehicles (lanes + parking) and 20% to people (sidewalks). Not to mention parking lots, parking garages, highways through the city…

The Economics Don't Work Either

Beyond the spatial impossibility, the economics of car infrastructure are just as broken:

• Each on-street parking space costs the city about $3,000 per year in maintenance and opportunity cost

• Each new structured parking space (~20 ft) costs $50,000-$90,000 to build

• Roads need to be repaved every 10-15 years at $1-2 million per mile

• The city's street maintenance backlog is already over $300 million

Meanwhile:

• A protected bike lane costs about $250,000 per mile and lasts 20+ years

• A dedicated bus lane is essentially just paint and signage

• A quality bus shelter costs about $15,000 (vs. $50,000+ for a single parking space in a garage)

The Actual Solution

So if more car infrastructure isn't the answer to Philly's mobility problems, what is?

The solution is actually pretty straightforward: make our current street space work more efficiently.

That means:

1. Reallocating street space based on efficiency

   • Converting some car lanes to protected bike lanes and bus lanes

   • Replacing some parking with loading zones, parklets, and bike parking

   • Widening sidewalks on commercial corridors

2. Focusing on moving people, not vehicles

   • Setting targets for transit frequency and reliability

   • Making transfers between modes seamless

   • Improving pedestrian crossing times

3. Stop subsidizing car storage

   • Performance-based parking pricing that reflects real demand

   • Using parking revenue to improve alternatives

   • Requiring new developments to unbundle parking from housing costs

The beautiful thing is that we don't need to invent any of this. These solutions are working in cities around the world with similar constraints to ours.

But I Need My Car!

I get it. Some people genuinely need cars for certain trips. I own a car myself. But the goal isn't to ban cars – it's to make them optional for more trips and more people.

When people who could easily walk, bike, or take transit choose to drive instead (because we've made the alternatives suck), they create congestion for people who truly need to drive.

Every person who switches from driving to an alternative is freeing up road space for someone who needs it more. It's actually the most pro-driver policy possible.

The Path Forward

We need to acknowledge the mathematical reality: there isn't enough space in Philadelphia for everyone to drive for every trip. Not now, not ever. It's not a policy choice – it's spatial geometry.

The question isn't "should we accommodate more cars?" but rather "how do we move people safely, efficiently, and comfortably with the limited space we have?"

And the answer, overwhelmingly, is to invest in space-efficient transportation: walking, biking, and transit.

Trying to solve mobility, housing, and any other city planning problems with more car infrastructure is like trying to get more vegetables in your diet by eating Impossible Burgers. It’s technically what you’re looking for, but it’s probably not going to help how you want it to.

It's time to stop throwing good money after bad and invest in solutions that actually work within Philly's spatial constraints.

Let's make getting around suck less – by making peace with our city's inherent geometry.