Safety First

Tag: Safety First

Springing Forward

It is that time of year where the days get longer, aided by a single leap and bound.  This Saturday into Sunday, much of the US will push its clocks forward by one hour.  Despite the “Daylight Savings” moniker, there is no actual daylight saved — it just shifts an hour from the morning to the evening.   The consequences of this likely will affect whether some people live through the rest of March or not, as I pointed out in the New York Times Room for Debate section a few years ago.  My contribution has to do with the changes in pedestrian fatality risks and total fatalities associated with the time change.  I also wrote a more general piece for the Appleton Post-Crescent.  Below is my semi-annual rehash of a previous post…

So, what does a time change look like?  Glad you asked:  The figure from the sunshine authority,, shows daylight patterns for our own Appleton, Wisconsin.  Each day starts with midnight at the bottom and goes to the top, and the months go left to right.  The blue line is the dawn and the red the dusk.

The Appleton Day
Appleton Time

The switch to DST in March and the switch back to standard time in November are clear — they are the discontinuities (the “breaks”) in the sunrise and sunset curves.  Because we “spring ahead” one hour, the sunrise time on Sunday morning will be one hour later than it was on Saturday.  An early morning walk that was in that daylight on Saturday will be in the dark on Sunday.  To have a sunrise at the same time as Saturday’s, we will have to wait until early April.  The opposite happens in the evening.  Sunset will be one hour later starting on Sunday.  There will be less light in the morning, but more light in the evening.

Light and visibility are extremely important determinants of traffic safety, particularly for pedestrians.  Paul Fischbeck and I looked at data from 1999-2005 on fatalities and travel patterns, and determined that the morning risk increases about 30% per mile walked, while the afternoon risk falls close to 80%.

The figure below shows pedestrian fatality risks from 1999-2005.  The blue and maroon bars show fatality risks per 100 million miles walked in March and April, respectively.  Note that for the 6 a.m. time slot the risks increase about 30%, whereas for the 6 p.m. time slot the risks take a sharp nosedive.  At midday the risks stay right about the same (we found no statistically significant difference in risks for that time period).  Overall, total pedestrian fatalities decrease in the Spring both because risks fall more in the evening than they rise in the morning, and there are many more people out later in the day.

Ped Spring

These data are rather crude in the presentation, as they do not focus specifically on the days leading up to and immediately following the time shifts, which is how researchers typically isolate the effects of the time change.

Here are some references for those interested:

S A Ferguson, D F Preusser, A K Lund, P L Zador, and R G Ulmer “Daylight saving time and motor vehicle crashes: the reduction in pedestrian and vehicle occupant fatalities,” American Journal of Public Health 1995 85:1, 92-95

J M Sullivan and M J Flannagan, “The role of ambient light level in fatal crashes: inferences from daylight saving time transitions,” Accident Analysis & Prevention, 2002 34:4, 487-498

D Coate and S Markowitz, “The effects of daylight and daylight saving time on US pedestrian fatalities and motor vehicle occupant fatalities,” Accident Analysis & Prevention, 2004, 36: 3 351-357

Consider a Jacket

One of my favorite features at the Cheap Talk blog is Consider the Equilibrium, where, as you might expect, the authors consider the equilibrium outcome in scenarios ranging from bike sprinting to inferring the quality of Asian restaraunts.

This week they tackle the dicey problem of dual-zone vehicle climate controls.

Oh, and coincidentally enough, I was telling my Econ 280 class yesterday that men should ride shotgun because she is safer.

I talk the talk, but do I ride the ride?  

Safety First

“The safer they make the cars, the more risks the driver is willing to take. It’s called the Peltzman effect.” — Some CSI Episode

The basic idea is so simple that it’s hardly controversial.  If you reduce the cost of doing something, you would expect more of it.  The classic Sam Peltzman paper has to do with making cars safer, which reduces the costs (in terms of potential injury or fatality) and hence increases “driver intensity,” as Peltzman puts it.  The startling result is that the behavioral changes completely offset the technological improvements, though this does not have to be so.

This is similar to the “rebound effect,” where improving energy efficiency or fuel economy, for example, causes people to set their thermostats more aggressively or to drive more miles (that is, because the marginal costs go down).

The Peltzman effect has crept into my RSS feed twice in the past week.  From this morning’s Marginal Revolution:

The NHTSA had volunteers drive a test track in cars with automatic lane departure correction, and then interviewed the drivers for their impressions. Although the report does not describe the undoubted look of horror on the examiner’s face while interviewing one female, 20-something subject, it does relay the gist of her comments.

After she praised the ability of the car to self-correct when she drifted from her lane, she noted that she would love to have this feature in her own car. Then, after a night of drinking in the city, she would not have to sleep at a friend’s house before returning to her rural home.

Well, that certainly makes me feel safer.

One of the classic jokes associated with the Peltzman effect is that NHTSA should put a spear extending out of the steering column, making the driver exercise extra caution so as not to be impaled. In that vein, the good folks at Organizations & Markets alerted me to this cartoon:

Pretty funny.

Peltzman is one of the most prominent empirical economists ever.  Certainly, having an “effect” named after you is a pretty big deal.  Some of the more astute of you also recall Peltzman from the Stigler-Peltzman capture theory. Love him or hate him, he is an interesting character.  I recommend this interview at EconTalk.

Liability for Harm Versus Regulation of Safety

That’s the classic question that Steven Shavell posed 25 years ago, and the debate over whether these two are potentially substitutes continues today.

The BP catastrophe has certainly brought more than its share of discussion on the issue.  Paul Krugman weighs in on the side that the continuing spill is Exhibit A that liability is a failure the private sector needs a stern regulatory hand to guide it.  Tyler Cowen frames the argument and takes Krugman to task on one point:

There is in fact an agency regulating off-shore drilling and in the case under question it totally failed.

Point, Cowen.

Of course, not all regulation is as inept as the Minerals Management Service (MMS) seems to be in this case.  One problem is that MMS is charged both with regulating environmental and safety concerns AND is responsible for approving leases to the provide sector.

And, which do they choose? According to the Washington Post:

Minerals Management Service officials, who can receive cash bonuses in the thousands of dollars based in large part on meeting federal deadlines for leasing offshore oil and gas exploration, frequently changed documents and bypassed legal requirements aimed at protecting the marine environment, the documents show.

Emphasis is mine, though the point sort of jumps out at you, doesn’t it? But, it’s not like the appearance of financial impropriety is a new thing with the MMS.  On the heels of the spill, in fact, President Obama recommended bifurcating the agency to mitigate the clear incentive compatibility problem.

Continue reading Liability for Harm Versus Regulation of Safety