Musing about traffic forecasts

I wonder if there is any point to making traffic forecasts. Everybody likes weather forecasts and economic forecasts, and even global warming forecasts and peak oil forecasts. But I don’t see any traffic forecasts being made, and I’ve been thinking about why.

First off, I can’t see any direct benefit of making traffic forecasts. In the end, the information isn’t all that informative. The signal, the interesting and novel bit of information, must be something you didn’t know already, otherwise it isn’t informative. Traffic is always the same, save for the occasional incident, and the average driver sees and measures it every day. Therefore a prediction of traffic probably contains very little information to the consumer of the prediction, and so it isn’t likely that anyone will be willing to pay for traffic information.

Second, there is no benefit to the forecaster. With financial forecasts, you can make some real money. If I predict China does/doesn’t have an economic bubble and will/won’t go down the toilet, I can place bets (oops, pardon me Wall Street isn’t Las Vegas, so I really mean “buy stock in or sell short”) companies that will be affected by what I predict are the most likely outcomes. This is not the case with traffic. Even if I predict an accident on Interstate 5 at 8:05 AM next Tuesday, and it happens, and people plan accordingly, they’ll save a small amount of time and most likely be inconvenienced even more by adjusting their schedules and deviating from their usual routine. And the prediction isn’t likely to come true, and when discounted accordingly any traffic prediction is worthless. So who would pay me to make my forecasts?

It all seems pretty pointless. Unless one is stuck in traffic, wondering why no one could predict this jam and why no one is doing anything about it.

Which brings to mind the idea that people are uninterested in traffic forecasts because traffic is at once our own fault, and eminently repeatable. We condition ourselves to leave at the same times everyday to get to our destinations at the appropriate time given our daily re-appraisal of prevailing traffic conditions. The only unknowns are traffic accidents, which can’t really be predicted, and unknown trips, for which the prudent allow copious amounts of time.

And that leads to my last point. What if we could predict traffic accidents? Should we do so? Suppose we could say with some confidence that every day from 8am to 8:30am on such and such a stretch of highway the relative risk of an accident is 1,000% higher than usual, perhaps due to a regular surge of traffic at that time or they way the sunlight hits drivers’ eyes, etc. Sure the absolute risk of an accident would still be microscopically small, but over a year you might see 2 or 3 more accidents at that time and place than elsewhere. So suppose we go out on a limb, and publicly predict a higher relative risk of an accident, and then lo and behold an accident does occur. Will we the predictors be held legally liable for the accident? Will the victims’ families drag us into court and ask the judge “If they knew there was a higher risk of an accident, why didn’t they do something about it?” I’d answer that I did do something about it…I made a prediction and publicized it.

In the end it is probably better to just keep quiet, and tell people traffic is bad because they like to travel about all day long.


Instead, we’re researching how to predict traffic accidents from observations of the dynamics of traffic flow.

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