Traffic and Its Avoidance

Traffic is by all accounts the biggest problem for urban mobility. Even Elon Musk famously agrees even though he hasn't acted on that in any useful way. Cars create traffic, traffic slows cars, slow cars make everyone annoyed and everything worse.

So the logical thing to do is to try to shift people out of cars for trips. 

Why focus on reducing cars instead of reducing, say, trips? Multiple reasons, but in short: cars take more space per person than other modes and cars produce longer trips than most modes; thus the same number of the same purpose of trips can be undertaken with much less traffic if you get people out of cars.

Well, if you do it right.

1. Transit Needs Out of Traffic

Just providing something other than a car doesn't do it alone, because if the other option is less pleasant, less useful, and/or markedly slower than the car option, even in bad traffic, people will still use cars.

And many transit options are all those things. Transit inherently has to deal with not being under the control of the individual: I don't get door-to-door trains, so it's marginally to very less convenient depending on parking, distance to train station, etc. And I don't control the timing either, but high frequency can mitigate that. What's worst, in my opinion, is when transit is still slower, or at least as slow, once you get on it.

Like this:

Can you see the buses? Can you see how they are stuck in the same traffic as all the cars?

Well, consider that they also stop more often (to let people on and off) and they become slower than the traffic, which is already very slow.

This means people are disincentivized from using it, because it's both slow and less convenient.

2. There Are Multiple Options to Avoid This

The good news is, you don't have to go all the way to a metro system to get ahead of traffic.

Now obviously grade-separated rail is good for this, since it literally doesn't intersect with car traffic, like this subway line in Toronto.

Nary a car in sight.

But you can also grade-separate light rail:

Or, naturally, real heavy rail:

And even a bus:

Well, in theory a bus: even though Connect is a BRT it's not actually grade-separated. But you get the idea.

You can also use signal priority to make sure transit (like these trams) moves before other traffic even at grade, thus reducing the traffic penalty on the tram or bus (metro/heavy rail are almost never subject to this):

The tram is at-grade with traffic but not actually in mixed traffic (itself an improvement) and signal priority lets it move as it goes rather than waiting.

It's rare in the US for, as far as I can tell, no good reason.

3. Adequate Replacements and Substitutes

One big issue in my recent trip to Toronto was that not only was the streetcar out for maintenance but its replacement buses ran in mixed traffic (see the first pic in this blog, which includes 2 of them). So even though the streetcar itself isn't optimal, since it runs slowly at grade, the substitute was even worse since it was repeatedly stuck in traffic.

Now, if that's occasional it's not the end of the world. But if the system isn't reliable and you end up with inadequate replacements/substitutes often, then even good transit on its original terms can end up repeling its audience back to cars and reinforcing the traffic vicious cycle. 

A city like Amsterdam (where buses can run on tram lines and there are multiple routes on transit from point to point) or London (where there are multiple modes from place to place) is much more resilient than a Toronto or worse a Quad Cities. And that ends up increasing traffic anytime something goes wrong--and it's a ratchet, only decreasing demand.

Traffic can be defeated by a robust, resilient, grade-separated or signal-prioritized transit system. Or by bikes, but that's a different article.