Bone-jarring park speed bumps widened

The in basket: Peter Madsen writes, “We were at Anderson Point County Park August 13, and I think that the county really got carried away with the speed bumps they installed. They are higher and more abrupt than any I’ve seen elsewhere, and even at dead slow speed our 2009 Accord bottomed out on the one next to the park entrance. So far it isn’t dribbling oil all over the place….

“Isn’t there some sort of a standard for speed bumps?” he asked. “More and more, your replies in this column strongly imply that there’s some federal or state standard for everything with regard to traffic. I’d think that the normal speed bump should be navigable by the normal average sedan without fear of damage. But those speed bumps are too abrupt and too high.”

The out basket: Peter e-mailed later that day to say a Facebook post from someone else said the bumps had been smoothed, and by the time I got out there, four of the five were widened to a comfortable level. But the fifth one, the one closest to the parking lot, was bone jarring. It was as bad as some you will encounter in some mobile home parks or the ones that were briefly in place at South Park Village Shopping Center in South Kitsap a few years ago before, I assume, shopper protest got them lowered and/or widened.

Doug Bear of Kitsap County Public Works, which did the work for the parks department, said, “The original speed bumps installed were not viewed as being effective in slowing traffic. They were built up, then residents and park visitors felt they were too abrupt. So the bumps were lengthened to create 12 feet long speed humps which are in place now. These conform to the existing county standard.” The fifth one was to be smoothed that day, he said.

As for standards for installing them, Jeff Shea, the county’s traffic engineer says, “Traffic calming devices that cause vertical displacement are usually called either speed bumps, speed humps, or speed tables.  Speed bumps are generally small and generally very abrupt.  They are used in parking lots quite often.  They are designed to force a vehicle to nearly come to a stop to maneuver over them. Kitsap County doesn’t use these on public roads.

“Speed humps are less abrupt, but do require a significant speed reduction to go over them comfortably.  They are normally spaced to allow motorists to achieve the posted speed between the bumps while decelerating and accelerating.  Speed humps are used by the county on local streets.  Speed tables are even less abrupt and are used primarily on roads that have bus traffic and larger vehicles on them.” Tracyton Boulevard has speed tables.

“The Manual on Uniform Traffic Control Devices doesn’t spell out how to build nor does it give specifications for the shape of the device,” Jeff said.  “The MUTCD gives the signing and marking requirements if speed humps or tables are used.

“The MUTCD doesn’t require signs, but recommends them with an Advisory Speed sign below the warning sign.  If (pavement) markings are used, it specifies how those markings should look and be placed.

“There is no federal requirement on the dimensions of a speed hump or table. Kitsap County tries to get their speed humps to about 3 inches (tall).  The width of the speed hump is usually about 12 feet. The speed humps can be formed into several shapes.”

Getting the humps to look as planned is a challenge, he said.  “Kitsap County builds their speed humps from asphalt. It is extremely difficult to screed the hot material into one of the shapes and compaction of the asphalt will impact the actual final height of the speed hump. This explains why speed humps around the county can vary in their impact to motorists.

“We could build them closer to the specifications, but that would take concrete.  Concrete costs significantly more and requires a much longer cure period before traffic can drive on it.

“A speed table is simply a speed hump with a flat top,” he said.  “The flat area is normally about 10 feet long.  The flat top makes if a little more comfortable for long wheelbase vehicles to maneuver over the device.  It also allows passenger vehicles to traverse a little faster than over a speed hump.”

I notice that the county’s signs warning of them call them ‘speed bumps’ and urge a 10 mile-per-hour speed to cross, though they really are speed humps. Bremerton’s signs say “speed humps” and urge 15 mph, though there’s not much difference in the two jurisdictions’ humps.

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