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. Mike B says:

    The school holiday effect is far larger than the Jewish effect. I notice the same thing on election days in the city where I work because city public schools are closed on those days. Remove the buses, school staff and parents from the highways and thhe roads run very smoothly during the peak periods.

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  2. brett says:

    it’s definitely not ‘jews are the worst drivers’ – it’s OLD people are the worst drivers. get them off the road for the day, and everything gets better. see?

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  3. GEP says:

    Yes, yes, public transportation should be FREE. Just think of all the problems that would solve. Pollution, accidents, gas prices would drop. I remember visiting Ketchum, Idaho, years ago, and enjoyed their free buses. Hope they still have it.

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  4. Michael H. Wilson says:

    I’ve noticed a similar thing in Portland, OR. Every time there is a holiday where government employees are off the seats on the lightrail to downtown are virtually empty. As a friend once pointed out, you could roll a bowling ball down the center of one of the lightrail cars and not hit anyone.

    If the goal is to reduce the number of vehicles on the roads why not repeal some of the regulations that make it difficult for private owners/operators to enter the business?

    I could be wrong, but I understand that in most cities across the country it is difficult, if not impossible to compete in the urban transit market. Wouldn’t jitneys, ride sharing taxis and private bus companies help in a number of ways?

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  5. agb says:

    For three months, July, August, and September 1986, I commuted by car into northern Manhattan on the Palisades Parkway in northern New Jersey then across the GW Bridge. My trip took 1 1/2 hours in July and August, no delays, 2 hours after Labor Day, major delays both on the Parkway and at the bridge. Maybe a guess of 10% fewer drivers during the summer months. A small amount does make a huge difference in the carrying capacity of a road.

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  6. Heavy D says:

    IT was a new twist to the term, “Let My People Go!”

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  7. Al Dugan says:

    Not too hard to figure out. I commute by car 27 miles into Manhattan from NJ every day and have done so for the last 30 years. This current downturn in the economy has led to perfect traffic conditions. If I wasn’t so worried about my job, I would be happy that it takes me less than an hour to get in and 45 mins to get home.

    Easy to figure out how much the toll collections have dropped at the major crossings.

    I would much rather know the percentage of Jews who took off work on Yom Kippur vs the percentage of Jews who went to services. Any guesses?

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  8. Jonathan says:

    Same thing happened during the 1984 L.A. Olympics. Just enough people shifted their schedules because of a fear of traffic-to-end-all-traffic. As a result, traffic was the smoothest it has ever been.

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