A Gut Yontif for L.A. Drivers

As I was out driving on the recent Yom Kippur holiday (sorry Mom and Dad, but at least I fasted!), I enjoyed what seemed like a miracle: swiftly flowing traffic in the middle of the day on the streets of West L.A.

This was no fluke; there’s a big improvement in the Westside traffic situation every year on the Jewish high holidays. To many, this seems mysterious. True, West L.A. and the southern San Fernando Valley have large Jewish populations, but not that large. How can the removal of a relatively small number of cars be responsible for such a marked drop in congestion?

The reason is the non-linear way in which traffic congestion builds. Each car added to a road creates a very different amount of delay, depending on how congested that road already is when the car enters.

Quite obviously, many cars can be added to a facility without creating congestion at all as the road fills up.

However, when a road reaches capacity, order breaks down very quickly. At that point additional cars impose a comparatively large amount of delay, quite out of proportion to their small numbers. This slows vehicles upstream and ultimately throughout the entire road system.

The bad news? Since the addition of a relatively small amount of new traffic can cause lots of congestion, modest increases in, say, population or economic activity can result in considerable trouble.

But the good part is the converse: getting a fairly small number of cars off the road can greatly improve conditions. This augurs well for solutions like congestion pricing (which I blogged about here and here), because if dissuading only a few drivers will make a significant difference, the tolls may not have to be draconian.

Another option is hoping the Presbyterians do their part by discovering some new driving-light holidays of their own. But that’s pretty doubtful at this point. So why not think about congestion pricing? A small toll can have big effects.

Happy holidays!

(Hat tip: Martin Wachs, RAND Corporation)


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  1. CK says:

    In that case, we should continue to push for car-pooling, bicycling to work, and taking public transportation as well?

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  2. jimi says:

    Maybe Jews are just the worst drivers?

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  3. Eric M. Jones says:

    Alternatively, perhaps a lot of people become Jewish just for a day.

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  4. Jonathan Brown says:

    I’ve noticed the same thing in Boston traffic. In fact, my theory – rooted in conjecture which I will share with you now – is that if just 3% of the commuting population is off the road, traffic is fine – barring weather disruptions. Jewish holidays, Arab Holidays, school vacations, seem to work. I’m not a big fan of congestion tax – but maybe there could be a way of incenting more people to work from home….?

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  5. Dan says:

    Why not pay people to ride buses (or provide the ser vice for free).

    It could decrease vehicles on the road and stimulate the economy. (More people might shop if they can get there free (or get paid a small fee to ride)).

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  6. Traciatim says:

    CK beat me to it, I was going to mention that this should make the case that in order to improve traffic situations everywhere there should be huge pushes on to support public transit. Possibly even make the public transit system free or incredibly low cost.

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  7. MG says:

    Making public transit free can encourage riders, because everyone loves soemthing free. Additionally, this can improve bus efficiency. If the drivers doesn;t have to wait for people to deposit their exact change or show their pass, people can get on the bus quicker, and even use the backdoors to get on, so the bus can just get on it’s way faster. And if buses are quicker and punctual, that encourages ridership even more. Everyone wins.

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  8. Mike says:

    Some public schools now close on Yom Kippur. I think this has a more significant affect on things than getting all (or should I say many of) the Jewish drivers off the road.

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