And it’s not just low overpasses SEPTA would have to worry about: some traffic signals dangle above the street at a height low enough for double-deckers to hit.

Even though TfL has operated double-deckers since the 50s, London also has some low overpasses where only single-story buses can operate. So why couldn’t SEPTA do the same thing, and run shorter buses on those lines?

Because the United Kingdom never had a race problem like America (at least, not until recently).

In America, transit authorities like SEPTA need to comply with Title VI of the Civil Rights Act of 1964. Title VI prohibits discrimination on the basis of race, color and national origin by any recipient of federal financial assistance.

If SEPTA gave some neighborhoods better buses than another – like upgrading the buses servicing Chestnut Hill but using old jalopies in Strawberry Mansion– then it would violate Title VI.

To prevent that from happening—even inadvertently—SEPTA has a policy of rotating its buses. “The buses get shifted from depot to depot,” said SEPTA’s Smith. “Our average bus is 6.5 years old; we try to maintain that [age] at all the depots.”

Adding a series of new buses that couldn’t run on certain lines due to height restrictions would add a bunch of logistical headaches that SEPTA simply doesn’t want to deal with.

WINDING YOUR WAY DOWN ON BAKER STREET… IN A BENDY BUS

Title VI isn’t the only federal law that makes double-deckers rare in America. The so-called Buy America Act requires transit agencies that accept federal funds to purchase American-made equipment.

Perhaps not surprisingly, there aren’t a ton of US companies that make double decker buses. That’s started to change recently, with Las Vegas and Minnesota finding American companies to do completion work on buses designed and partially built by Scotland’s Alexander-Dennis Ltd., thereby technically complying with the federal law. It’s what legal experts call a “loophole.”

Neither of the companies SEPTA currently purchases buses from—New Flyer and Nova Bus—offers double-deckers.

Now, I know what some of you are thinking right now. “STOP FEEDING ME YOUR LIES, SAKSA! THOSE ARE BOTH CANADIAN COMPANIES! THAT’S WHY SEPTA BUSES REEK OF MAPLE SYRUP!”

First off, hey, why are you shouting? We’re talking about trade regulations and bus fleet acquisition, nothing to get too worked up about.

Second, you’re right, Nova Bus and New Flyer are both headquartered in Canada. But thanks to NAFTA and some World Trade Organization rules, goods made in the Great White North can sometimes satisfy the Buy America Act’s requirements. And, under the act, where the manufacturer is domiciled is less important than where the product is primarily built.

MORE REASONS THAN ALL THE UMBRELLAS IN LONDON

It’s not just far-reaching federal laws and low-hanging overpasses that make SEPTA less than keen on double-deckers, though.

Articulated buses sit more people than double-deckers. “Basically, instead of going up, we’ve gone long,” said Smith. SEPTA’s articulated 60-footers can fit 105 passengers (including standing passengers), but London’s New Routemasters can only hold 87. The double-decker’s novelty would wear off pretty quickly once they began skipping more stops than today’s articulated buses already do.

Overpasses and low traffic lights aren’t the only height restrictions SEPTA would have to deal with. Its bus depots weren’t built for tall vehicles. Same goes for SEPTA’s bus loops and repair shops. Building new or retrofitting the old facilities to make double-deckers fit would cost a prince’s ransom.