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Three types of rumble strip with different specifications installed on a test basis Test-driving/riding by road users
As there was a concern that motorcycle and bicycle steering would be disrupted, we installed rumble strips with different groove depths (9, 12 and 15 mm) at the Tomakomai Winter Test Track, which is owned by CERI. We had 62 subjects (ordinary road users) drive a vehicle or ride a motorcycle or bicycle on the test track to confirm the safety of vehicles passing over the strips. After the drive, we surveyed the users on their subjective evaluation of rumble strips. Grooves 12 mm in depth received the most favorable comments; thus, this depth was adopted as an installation standard.



Noise and vibration are effective even under such conditions. Snow melts and the road surface appears in sunny days Anti-freezing agent dissolves snow in grooves.
The photo shows rumble strips in winter. As the left photo shows, the noise and vibration occur even on snowy roads where the road markings are invisible, which was unexpected. This is a great advantage in warning deviating drivers even when road markings are covered by snow in winter. The snow removal and anti-freezing agent remove snow caught in grooves. No problems were identified regarding road maintenance.

Rumble strips have great potential as a “trump card” against head-on collisions. CERI hopes that this technology becomes widely applied and as many people as possible can be saved from fatal accidents.
Evaluation under winter road conditions
National Highway 274 in Hidaka Town, January 20, 2004
Vibration and noise were observed under winter road conditions. Vibration and noise can be observed even when markings are invisible due to snow cover.


Braking distance test under winter road conditions
Braking distance was tested under winter road conditions at Tomakomai Winter Test Track. The deeper the rumble strips, the shorter the braking distance, due to the uneven surface.

Noise in a vehicle driving on a rumble strip
The noise in a car driving on a rumble strip is 15 dB or more higher than on a regular road. The deeper the rumble strip, the louder the sound. Likewise, the faster the driving speed, the louder the sound.
Measuring method
A noise meter was fixed to the headrest of the front passenger seat. The measuring conditions were as follows:
Noise meter: regular noise meter (NL-22), manufactured by Rion, measuring interval of 0.1 sec
Vehicle: Nissan Wingroad (2001), 4 WD 1800 cc, 185R14 tires
Aggregation method: The highest noise in each drive was collected. The value for each speed is an average for three test-drives.
Vibration in vehicle driving on rumble strip
The vibration in a car driving on a rumble strip is 10 dB or more higher than on a regular road. The deeper the rumble strip, the greater the vibration. The vibration takes a local minimum at 60 km/h, but after that point, the faster the driving speed, the louder the sound.
Measuring method
A vibration meter was fixed to the steering column. The measuring conditions were as follows:
Vibration meter: general-purpose vibration meter (VM-82), manufactured by Rion, measuring interval of 0.1 sec
Measuring vehicle: Nissan Wingroad (2001), 4 WD, 1800 cc, 185R14 tires
Aggregation method: The average of the 10 greatest vibrations when driving on the rumble strip was collected. The value for each speed is an average for three test-drives.