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Where were rumble strips developed? |
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The first rumble strips were installed in 1955, in New Jersey, U.S.A. They were called “singing shoulders.” They were wavy bumps installed at the concrete-paved shoulder of a bridge. In the 1960s, rumble strips of various designs were adopted in many states. In the U.S., a method of milling paved roads was developed in the 1990s and it spread rapidly. Its profound effects have been reported recently. The rumble strips in the U.S. are mainly installed on highway shoulders as a countermeasure against run-off-the-road accident. CERI has introduced rumble strips designed for centerlines as a measure against head-on collisions. |
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How effective are they? |
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In Colorado, U.S.A., it is reported that head-on collisions were reduced by approximately 36%, after installation at the centerline of two-lane local roads for 27 km in length, in a comparison between before and after 44 months of installation.
In Japan, the first milled rumble strip was installed on a 700-m section of National Highway 5 in Yakumo Town in July 2002. Since then, no head-on collision has been reported on that section. We will continue to monitor this for the long term.
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How many installation locations are there, and what is the installation length in Hokkaido? |
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As of June 2005, rumble strips were installed on 27 routes and its length adds up to 291 km. For details, please see Diffusion. |
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Are they safe for cyclists and motor bikers? |
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Two experiments were conducted (one in 2002, with 62 test drivers; and another in 2003, with 105 test drivers) for motorcycles and bicycles at our Tomakomai Winter Test Track.
The experiments included free driving/riding on a road installed with rumble strips. These trials were video recorded and analyzed by researchers. The experiments included a questionnaire on the safety of the strips for driving/riding. No dangerous driving/riding was identifiable on video observation. However, the questionnaire survey revealed that some respondents felt in danger when riding bicycles on grooves 15 mm in depth. Consequently, the 12-mm depth is adopted for rumble strips as the standard on national highways. Note that currently rumble strips are installed at the centerline of sections with double solid-yellow centerline markings (no overtaking), so few bicycles pass over the strips. Just crossing a rumble strip with a bicycle is not problematic.
For motorcycles, rumble strips are safer than center poles or jiggle bars (the square-shaped convex metal with reflector).
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Does installation reduce the pavement durability? |
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July 2006 marked the fourth anniversary since rumble strips were installed. In some locations, spalling occurred, sometimes exposing the pavement joint. This is attributed to the thinness of the overlay. For details, refer to Caution after installation.
On road sections with a single solid-yellow centerline, the paint reduces spalling and prevents water penetration by sealing the joint. |
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Are they still effective in winter? |
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On snow that has not been compacted, the noise and vibration still can be noticed even if the rumble strips are covered by snow. Also, under road conditions where the snow removal standards for main highways are applied, snow caught in grooves disappears. For more details, see Evaluation of rumble strips. |
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Aren't there noise problems? |
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We measured the noise at the roadside when a passenger car (1800 cc) drove on grooves 12 mm in depth. The noise was 70 dB, only 1 dB higher than that measured for the vehicle driving on the regular surface. Also, since the rumble strips are installed at the centerline of no-passing sections, vehicles rarely encounter them. Therefore, no issues of environmental standards arise. |
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How are specifications determined? |
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Refer to Rumble Strip Installation Guidelines (Draft) |
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Is it OK to install them at curves? |
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In Hokkaido, you can find many rumble strips installed at curves. Currently, the 9-mm depth is adopted for curves, whereas the 12-mm depth is adopted on straight sections. The shallower depth at curves was adopted because motorcycles may pass on the centerline rumble strip. It is possible that the depth of rumble strip will be set uniformly at 12 mm in the future, as a result of observation after installation. |
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What are the installation costs? |
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According to figures from 2002, the cost was 1,500 yen per meter. But the cost may vary by road condition, such as the slope or snow accumulation. Also, it is possible that the costs in Hokkaido may differ from those in other regions. Contact us for more information. |
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Are there instances of rumble strips installation on sections with single yellow lines (no-passing) or at shoulders? |
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In 2003, CERI developed specifications for rumble strips on single solid- yellow centerline markings (no overtaking) or at shoulders, and tested such strips at the Tomakomai Winter Test Track. The Hokkaido Regional Development Bureau is planning a trial installation with these new specifications on national highways in fiscal 2004, to confirm their safety. |
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