March 3


The All New Mumble Strip

By Mike Spack

March 3, 2015

Guest Post by Max Moreland, EIT, Traffic Data Inc/Spack Consulting/

The NCITE February 2015 section meeting was held this week and featured a presentation by Derek Leuer (MnDOT Assistant State Traffic Safety Engineer) on MnDOT’s efforts to improve rural roadway safety.  The presentation had a focus on low cost ways that can be applied system wide to improve roadway safety.

Among the various methods MnDOT has successfully used to improve safety were rumble strips.  Rumble strips are small divots placed on the outside edge of a lane and/or along the centerline of a road that rattle your vehicle and make a buzzing noise if you drive over them.  This rattling and noise sends a clear signal to the driver to pay attention and get back in their lane.  Rumble strips are a cheap and easy safety feature that have significant positive impacts.

When a driver rolls over a rumble strip the buzzing noise adds to the vehicle vibration to alert the driver.  However, this buzzing noise is not only audible to the folks in the vehicle.  Noise from rumble strips can be a nuisance to nearby residents.  Unless you live near a musical highway of course.

One way MnDOT is looking to get the best of both worlds (keeping rumble strips and reducing exterior noise) is through the use of sinusoidal rumble strip design, aka mumble strips.  These mumble strips still vibrate and create noise inside the vehicles, but do not produce much exterior noise.  Here’s a demo video –

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Mike Spack

My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

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