Trying to understand and be able to explain the difference between speed bumps and speed humps.

[liitts]

I need to be able to explain the difference between speed bumps and speed humps to an audience that believes they're the same devices and has a vested interest in maintaining that belief, both for themselves and others. First, of course, I need to thoroughly understand the difference, and I'm working on that. In working on the presentation I will be giving, I have come up with a little narrative that I think will be understandable to them and won't be as dry as just saying the travel distance across one is thus and so and across the other thus and so. What I want to say is:

"Let's say the front wheels of your car start across and get to the top of the rounded traffic calming device in front of you. If the next thing that happens is that those same front wheels go over the top and down onto the level roadway, you have just crossed a speed bump with your front wheels. However, if the next thing that happens is that your rear wheels climb and reach the top of the same traffic calming device, your car is crossing a speed hump."

My question is: Is the above a correct statement?

If you wonder why I'm so interested in this, see [link leaburgdamspeedbumps.info]leaburgdamspeedbumps.info[/url]

Any help you can give me will be greatly appreciated!

 

[IRstuff]

It does appear, as discussed in your website, that speed bumps are no longer in vogue.

http://www.ite.org/traffic/hump.asp

This is a good resource.

http://www.ite.org/traffic/tcstate.asp

Chp 3 discusses humps, and not bumps:

http://library.ite.org/pub/48b037de-a555-47f5-2651-bb412d17bab5

Note that humps are defined with specific lengths, typically 12 to 14 ft, but even longer ones exist, although they might be considered speed tables at that point.

http://www.ite.org/traffic/table.asp

which are 22 ft in length.

Chp 6 explains that bumps can cause vehicle damage, opening up the possibility of liability claims:

http://library.ite.org/pub/e27834ad-2354-d714-5110-7536dcc4a8c0

see pg 132 and 133 in particular,

In Vicksburg v. Harrellton, a landmark case, the Mississippi Supreme Court ruled that speed bumps constituted an inherent danger to motorists. The Connecticut courts reached the same conclusion, but had another reason for declaring them a public nuisance: Their low design speeds could so delay emergency vehicles as to cause serious injury or loss of life.9 An occasional bump can still be found on a public roadway.

I got all this from Google...

Hope this helps.

TTFN
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[TerryScan]

I do not believe your presentation quote above lends much clarity to the difference between a speed bump vs hump.

The simplest difference appears to be that Speeed Bumps are typically 1-3 ft. from beginning to end while Speed Humps are typically 10-14 ft. This variance results in a radically different surface slope resulting in a significantly different impact on the travelling vehicle.

 

[GeoPaveTraffic]

The big design aspect of a speed hump is that they are designed for a specific speed. A vehicle crossing at that speed or slower just feels a hump and not a jarring bump. A vechical going faster than the design speed will feel more of a bump.

A speed bump on the other hand is jarring at any speed.

I generally agree with your description of a speed hum, although I expect that examples could be found that do not agree.

Mike Lambert

 

[chicopee]

From the explanations given above, both terms seem to give credence to the term "silent policeman."

 

[IRstuff]

Currently, what I encounter is the classic speed "bump" located in a large parking lot, at a store, mall, or school, where the priority in liability shifts from car damage to risk to pedestrians in the parking lot.

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[MikeHalloran]

To me, the clearest distiction is the radius of the transition between pavement surface and bump/hump surface.

I.e., the typical speed bump has a sharp transition at its leading and trailing edges, so that an abrupt shock motion is induced in a traveling wheel of any radius.

Whereas, a speed hump has a transition radius greater than the radius of the typical vehicle wheel, so a shock is induced to the vehicle only when the vehicle is traveling faster than a certain critical speed. The critical speed is determined by the relation between the vehicle's natural frequency in bump, and the frequency corresponding to the hump's leading edge at the vehicle velocity, taken as an inverted cosine.

The shortest speed humps around here comprise a complete inverted cosine cycle of about six feet in length. Longer ones have flat tops and are about half a car length.





Mike Halloran
Pembroke Pines, FL, USA

 

[GeoPaveTraffic]

Good explaination Mike H.

Mike Lambert