By Jonathan Krall

Everybody wants to fix traffic congestion.

“Our roads are congested! We should do something about it,” say otherwise-sensible adults all the time. And otherwise-sensible community leaders reply by saying they are working on it. Whenever I see this issue raised in the press, I imagine a petulant child saying, “I want a pink unicorn! With sparkles!” And a parent who patiently replies, “I’m working on it.”

It isn’t the same thing, but it’s pretty close.

The reason we have traffic is because we have an overabundance of people who would happily drive if there were less congestion — and we do very little to discourage them. We let people take up space on our roads at bargain-basement prices, and people rush to fill them. Because we have a better-than-average transit system, those people fed up with driving on crowded roads already have switched to transit, bicycling, car-pooling or telecommuting.

Sixty percent of Alexandria’s commuters drive to work each day. Many of the rest, and many in adjoining jurisdictions, are waiting in the wings to snap up road space if we decide to build more lane miles here. This is why building more roads cannot reduce congestion in a crowded city: People will rush to fill the new lanes. Less congestion-tolerant drivers will switch back to transit, and we will end up where we started.

All we get when we add lanes is more cars, sitting in traffic, spewing pollution. (A 2009 study showed that IQs of children in the most auto-polluted areas of New York were lower, on average, by 4 points. This same effect has been found in Krakow, Poland, and Chongqing, China.) In a crowded city, trying to fix congestion by building more roads is like trying to fix a crowded bar by giving away more free beer. Everyone will drink their fill and leave, right? It doesn’t work.

What we can do is add capacity to our transportation system — without adding more roads — so that those congestion-intolerant drivers won’t get back behind the wheel. Single-occupancy vehicles take up a lot of space. Trains, buses, vanpools and even bicycles take up much less space — per person moved — than cars. Replacing a traffic lane with a dedicated transit lane adds capacity, improves speed, decreases pollution and reduces noise.

For those of you who are still holding out for that pink unicorn, though, there is hope — of a sort. We could stop giving our roads away at such low prices. A concept called “congestion pricing” has been implemented in a few city centers. For example, London’s experiment in congestion pricing celebrates its 10th anniversary this year. It has kept congestion in check and, as expected with the capacity-adding strategies discussed above, inspired thousands to give up cars for bicycling and transit.

Congestion pricing is effective but less popular than adding and improving transit. Put simply, transit-related investments may not reduce congestion, but they do improve quality of life. Adding transit lines, improving transit-stop information, and filling gaps in our sidewalk and bicycle networks are improvements that make transit easier to reach and easier to use. Even if you can’t come up with a pink unicorn to satisfy a petulant child, you can improve their quality of life so much that they will thank you for it when they grow up.

– The writer is a member of the Alexandria Bicycle and Pedestrian Advisory Committee.