Traffic safety center at transportation research board 2007
Closing the Gate on Rail Crossing Crashes
An Evaluation on Where Best to Intervene
Between 2000 and 2004, 593 crashes occurred at public, at-grade rail-highway crossings, resulting in 99 deaths and 205 injuries. In a presentation at the 2007 annual meeting of the Transportation Research Board, "Rail Crossings: A Strategy to Select Countermeasure Improvements for Rail-
Highway Crossings in California," UC Berkeley Traffic Safety Center Director David Ragland said that the only way to prevent these types of accidents is to make it physically impossible for drivers to go around--or through--crossing gates. (Ragland's co-authors on the report were TSC researcher Douglas Cooper and graduate student Kara MacLeod.)
Of the crashes that occurred, 73 percent occurred at crossings equipped with gates, 59 percent involved vehicles moving over the crossing, and 27 percent involved vehicles that had driven around or through lowered gates. An unbelievable number, 21 percent, involved a vehicle running into a moving train.
In order to best utilize state and federal funding available for making the state’s 7,719 at-grade rail-highway crossings safer, Traffic Safety Center researchers collected and analyzed rail/vehicle crash statistics updated for the first time since 1999, analyzed the effectiveness of different types of railroad crossing warning devices, and prepared a cost/benefit comparison of various warning devices.
Among the methods they considered were
Long-arm gates, which extend across 3/4 of the roadway and discourage "drive-arounds;"
Median separators, a curbed area with reflectorized tubes that prohibit “drive-arounds;"
Four-quadrant gate systems, which extend across the approach and departure sides of roadway lanes inhibiting nearly all traffic movements over the crossing after gates have been lowered; and,
Photo enforcement that would capture the both a photograph of the violation, the driver, and the vehicle’s license plate.
Given the limited funding available, the researchers concluded that the highest benefit/cost ratio can be achieved with the use of long-arm gates. Installing median barriers where standard two-quad gates already exist came in a close second.
"The application of either of these countermeasures to the spectrum of multiple crash sites would—in theory—pay for itself within one year," the researchers concluded.
Why Big Objects Appear Slower
The larger question—why do people ignore warning signs, arms, flashing lights?— was addressed partially in a poster by TSC researchers, Joseph Barton of the Department of Mechanical Engineering, and the late Theodore Cohn of the School of Vision Science and Optometry (and presented by Barton). Their poster, entitled “A 3D Computer Simulation Test of the Leibowitz Hypothesis,” suggests that large objects, such as trains, are perceived as moving more slowly than they really are, and this may account for the higher accident rate involving larger vehicles such as buses and trains. This theory was first advanced by H.W. Leibowitz in 1985.
To test the theory, Cohn and Barton used five men ranging in age from the early 20s to the mid-50s with corrected normal eyesight to identify which sphere—a larger or smaller one—was approaching more quickly. The observers consistently believed the smaller object was moving faster—even when the larger sphere was, in fact, traveling twice the speed of the smaller. The reason for this misperception is the observers' reliance on monocular cues when making judgments about the speeds of approaching objects.