Speed Bumps And Speed Humps

May 18, 2009

Do Speed Bumps Provide Any Safety Benefits?

I found the following forum post at the US Department Of Transportation - Federal Highway Administration website which I would like to share with you here.   The thread provides an overview of the varied opinions  that exist related to Speed Bumps and Speed Humps on public roadways and highways and their safety benefits.

This discussion thread focuses on the element of safety and the question…

Do speed bumps provide any benefit to safety?

Re: Do speed bumps provide any benefit to safety?
Willie S ,

There is an effort underway to install speed bumps in my community. I am
struggling with this issue. I am extremely divided about whether these devices
increase or decrease safety. Can anyone one with experience in this area
provide any guidance. Thank You.

Re: Do speed bumps provide any benefit to safety?
Joe

It just depends on the situation. If they are designed properly (humps instead
of bumps) and are installed on a road with a bunch of speed related accidents
they may improve safety on that road. On the other hand, if they are not
designed properly or installed on a road that has had very few accidents they
might actually cause an increase in accidents — due to the potential for loss
of control over the bump etc. Speed bumps are a tool just like any other tool
used for roadway safety. If used properly they can be helpful if not,they can
cause more problems than they solve. There’s no universal right or wrong
answer. Each location must be evaluated given the conditions that exist at
that location.

Re: Do speed bumps provide any benefit to safety?
Kathy

I have been installing speed bumps (humps) in the City I work for the last 13
years. They have to be installed on low speed roads such as local streets or
neighborhood (minor) collector streets. We limit the speed to under 35 mph.
They would not be safe on higher speed roads or streets. The design we use is
a 14′ or 22′ bump no higher then 3″ at the crown. In those 13 years we have
not had a motor vehicle crash related to the bumps. Our studies show that they
reduce speeds overall. If you are using the correct design on the appropriate
street, they are very safe.

Re: Do speed bumps provide any benefit to safety?
Rob K

Overall, I tend to agree. However, as a traffic engineer, I am concerned with
stating that anything is “safe”, as that implies a warrantee of safety. I
typically make more watered down statements like “can improve safety”. I live
directly off a street with speed humps. While the speed humps may improve the
overall driver behavior on the road and dissuade cut through traffic, they have
contributed to (or maybe been a catalyst to) two specific reported collisions
that I am aware of on the road by where I live.

The first involved a person slowing to an extremely slow speed to cross the
hump being struck from behind by a following vehicle. The second involved a
young driver driving a souped up Mustang. He thought he crossed the last hump
in a series, and proceeded to accelerate at a high rate of speed (in front of
an elementary school), and proceeded to hit the final hump in the series at a
high enough speed that he peeled a tire off the rim, lost control and hit a
bridge abutment.

It is probably likely that the Mustang driver would have made a similar choice
elsewhere, and may have ended up in a similar end result, even if there were
not bumps. The underlying issue that I see is, even when the best improvements
are provided, there are always opportunities for people to choose to push the
limits or not pay attention, thereby compromising safety.

Re: Do speed bumps provide any benefit to safety?
Willie S

The location in which the speed humps are being considered are near a boat
landing & community dock that is situated along a 1/4 mile of straight ahead,
man made causeway. The boat landing & dock area are moderately congested on the
weekends and during peak seasonal months during the boating season. Parking is
perpendicular to the dock & along the shoulder of the causeway in a gravel
area. The parking area is in such close proximity to the causeway that dangers
exist when human activity and the oncoming traffic conflict with the terrain.
The total length of the causeway is approximately a mile long with
bi-directional traffic, 2 curves, shoulders, and flanked on either side by salt
marsh. The normal posted speed limit is 40 MPH. Speeds on the causeway have
been quoted as great as 60 MPH. On opposite ends of the causeway are the
approach entrances to the subdivisions where the speed limit is posted at 25
MPH. Even in these areas it is difficult to decelerate from 40 MPH down to 25.
From an engineering stand point I’m unsure if the terrain feature of the
causeway could support dual Speed Humps, positioned on the outer fringes of the
boat ramp & dock area to effectively reduce speed without causing a further
hazard. From a cost/benefit analysis as well as struggling with my own
conscience I don’t see an easy solution. Perhaps a multi-part solution is
required.

Re: Do speed bumps provide any benefit to safety?
Rebecca

It sounds like this straight highway has the visual of a high-speed facility.
How many lanes are there? If more than 1 in each direction, it may help to
reduce the number of lanes: make painted shoulders, or a painted central
median, or - Best - a landscaped central median. Reducing lanes may cause
summer congestion, but this is good - it will be a natural traffic calmer. You
do have options, and it may help to use paint (not concrete) first, as a trial
basis.

Re: Do speed bumps provide any benefit to safety?
Dave

It sounds like you might have a conditional speed limit zone where a 25 MPH
speed limit on weekends (or certain hours of the day) might be warranted.
Notice can be accomplished in various ways via signage. Is this an option?

Re: Do speed bumps provide any benefit to safety?
Willie S

Thanks all for responding. I appreciate everyone’s advice. I like the signage
idea. Possibly an amber flashing light above or attached to the sign to get a
drivers attention. As well as timer controlled during weekends and peak
seasonal usage. In the area directly before the dock and landing I have
installed new signs which reduce the speed limit from 40 MPH to 25 MPH.
Unfortunately, there will always be motorists that ignore these ordinance
signs. Additionally, I have had the sheriffs dept provide radar surveillance
and pass out a few speeding tickets. I have provided a Goggle link with
satellite view. http://images.google.com/maphp?hl=en&tab=il&q= Or you may
simply type in Herb River Drive Savannah Ga to view the terrain & causeway
features. I believe a periodic dose of speeding tickets could change the
behavior of speedy drivers.

Re: Do speed bumps provide any benefit to safety?
Dave

I agree with the first two replies. You can “google” the phrase “speed humps”
and come up with any variety of pros and cons about speed humps. One balanced
description I found comes from the city of Phoenix. See this link:
(http://phoenix.gov/STREETS/speedhmp.html).

In addition to the positive benefits, they list 8 potential drawbacks that need
to be considered when applying speed humps. For obvious reasons they don’t
mention interference with snow plowing equipment but this would fall under the
same category as street sweeping equipment.

Apply them right and they can help. If speed humps are won’t work for a given
location, above the road traffic calming alternatives might be considered.

Speed hump not a traffic control device
Dwight K

It may be worth clarifying, since this discussion somehow got started in the
“Signs” discussion area, and there has been confusion about this point in the
past: a speed hump is not any sort of “traffic control device” (”a sign,
signal, marking, or other device used to regulate, warn, or guide traffic,
placed on, over, or adjacent to a street, highway, pedestrian facility, or
shared-use path by authority of a public agency having jurisdiction”). Speed
humps are design features. Markings and signs, which are devices, are often
used to warn approaching drivers of speed humps.

Re: Speed hump not a traffic control device
Rebecca

It may also be worth clarifying, that a speed “bump” is different from a speed
“hump.” “Bumps” are taller over shorter cross distances, and their steeper
slopes pose more harm to vehicle suspensions and to emergency response vehicles
in particular. One must slow to 5 mph sometimes to avoid jarring the car’s
undercarriage. Speed “humps” have more gradual slopes and are shorter
overall. They are more easily traversed at reasonable (20-30 mph) speeds, and
pose less of an obstacle to emergency response vehicles. Therefore, Humps are
generally preferrable to Bumps.

[NOTE: The names and emails of those posting to this discussion thread were removed for privacy. You can see the thread in its entirety at http://knowledge.fhwa.dot.gov/cops/opspublic.nsf/discussionDisplay?Open&id=2E08816027C4584C852570F6006B8629&Group=MUTCD%20General&tab=DISCUSSION#2E08816027C4584C852570F6006B8629]
Even though there does not seem to be any clear cut answer to the question about the safety benefits of speed bumps in this forum post, you can certainly draw your own conclusions.   Feel free to comment about your experiences on whether or not speed bumps or speed bumps increase public safety right here.

and as always,

Till next time…

…Watch out cause there’s most likely a speed bump ahead!  :-)

February 14, 2009

Speed Bumps And Your Options

Filed under: Speed Bumps — Tags: , , — admin @ 1:00 pm

When it comes to speed bumps there really are only two options.

Rubber Speed Bumps or the “traditional” asphalt speed bump.

Which do you choose? Only you can decide but here are some guidelines on what to loo for:

- Raw Material or product costs

- Labor Costs for installation

- Equipment Costs for installation

- Freight or Transportation costs to the job site

Do a side by side comparison between the two options so you can decide which is the least expensive option for you.

Be sure to consider all the costs shown here.  And after you’ve considered them  be sure to look at other facots such as

- Durability of the speed bump

- How the speed bump are handled in winter weather conditions if they arte handled at all

- Replacement costs for speed bumps

- Maintenance costs

- Lifetime Cycles

- The Effects on Environment

Some of these are hard to monetize but considering all of these facotrs will enable you to make an informed choice between asphalt and rubber speed bumps.

It’s your choice!