Jeffery A. Jones
Human factors considerations in the design of rumble strips.
Proceedings of the 17th Canadian Multidisciplinary Road Safety Conference, Montréal, Canada.
Russo, F. A. & Jones, J. A.
published: 2007 | Research publication | Jones Lab
Rumble strips are raised or grooved patterns constructed on highway shoulders, centerlines,
and approaches to transition zones (e.g., railway crossings). When a vehicle makes contact with
a rumble strip, a low-tech multisensory alarm is activated. Although a number of technical
reports have considered different aspects of construction on crash statistics, human factors
considerations are less prevalent, and no study has examined the perceptual consequence of
altering the frequency of the repetition pattern. In Experiment 1, the effect of frequency on
perceived urgency in an auditory-only simulation of rumble strips was considered using a
magnitude-estimation task. Frequency of noise bursts was varied between 3.125 to 200 Hz
(corresponding to a groove-to-groove spacing of 8889 to 139 mm at 100 km/hr). Results
indicated that the ideal frequency range (yielding the highest urgency) was between 12.5 to 25
Hz, which is lower than the range (~90 Hz) produced by typical rumble strip spacing (~307 mm).
A psycho-acoustic explanation of this result is that the frequency range between 12.5 to 25 Hz
is within the range in which sequential noise bursts can be resolved but below the range in
which noise bursts fuse and give rise to a pitch percept (Miller & Taylor, 1948). In Experiment 2,
participants estimated pitch strength and matched the pitch of simulated rumble sound to a pure
tone. As expected, pitch strength estimates and the accuracy of pitch matches were consistently
low between 17 to 50 Hz but increased linearly with frequency beyond 50 Hz. On the basis of
this auditory-only simulation, it appears that rumble-strip spacing leading to audible but infra-
pitch sound is ideal.
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revised Mar 14/08
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