The Atlanta Bus Crash
Useful information from a risk analytic perspective

9 Mar 2007 in Regulatory Science, Information Quality

The tragic bus crash outside Atlanta killed five Bluffton University baseball players, the driver, and his wife. News reports indicate that many more remain hospitalized, some in serious or critical condition.

There is a great deal of commentary in the press and in the blogosphere, much of it focused on assigning blame. We are not going to add to that.

We provide links to the most useful information we've found of interest to highway risk analysts, who take seriously their commitment to improve safety but also realize that they cannot prevent all catastrophic bus crashes.

The crash occurred at the end of a left exit off a high occupancy vehicle (HOV, or carpool) lane. HOV lanes are popular in major urban areas but rare in the country. Left exits also are rare, but less so for HOV lanes. The Atlanta Journal-Constitution has published a helpful video of the exit ramp from the driver's perspective. Because the video was shot in daylight, it does not fully describe what the driver saw. Moreover, it cannot capture what he thought he was seeing:

Here is a graphic, also from the AJC, showing the intersection:

The prevailing hypothesis seems to be that the driver was unfamiliar with the neighborhood and did not know that he had exited I-75. This leads to the inference that the driver had inadequate information, such as insufficient warning or signage.

But more information is not always better. Helpfully, the AJC has raised the alternate (and opposite) theory of information overload. Below is an AJC graphic showing the signage before and at the exit ramp. Thus, just as it is plausible that the driver had too little information, it's also plausible that he had too much.

Atlanta Journal-Constitution Graphic: Information Overload?

Recognizing that blogs do not sample representative opinion, it is nevertheless instructive that the AJC's inquiry whether readers thought the exit posed a safety hazard elicited varied (and even opposite) responses, many of them strongly worded.

It is technically impossible to design an off ramp that satisfies all of the respondents. Some reader suggestions are intuitively appealing, such as the installation of roadway rumble strips on interstate highway exit ramps. However, it is inappropriate to assume that they will achieve the desired objective. For example, they could exacerbate a driver who is confused about his location and cause him to overreact. Also, their effectiveness is partly due to novelty. If they were installed at all interstate highway exits, drivers could become accustomed to them and subsequently pay less attention. This is what happened to center high-mounted stop lamps.

Risk experts often opine that untrained members of the public do not understand probabilities. In an interview with AJC reporters Kevin Duffy and Christian Boone, the father of one of the students killed says when he heard that there were six fatalities he had an excellent grasp of probability:

"I had a six out of 35 chance ... my son was dead," he recalled thinking.

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